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THESIS

RSITY LIBRARIES

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This is to certify that the

thesis entitled

MOISTURE ABSORPTION CHARACTERISTICS OF
100% RECYCLED CORRUGATED BOARD

presented by

SHU-SHENG WU

has been accepted towards fulfillment

of the requirements for .

MASTER PACKAGIN
degree in

 

 

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LIBRARY 1
Michigan State I
Universlty

 

 

 

 

 

PLACE u RETURN aox to roman ru- ehodrom from your record.
TO AVOID Flues Mum on or boron dd. duo.

DATE DUE DATE DUE DATE DUE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

MSU I. An Affimatlvo Wand Opportunity IMIWOI'I
Wins-9.1

MOISTURE ABSORPTION CHARACTERISTICS
OF 100% RECYCLED CORRUGATED BOARD

By

Shu-Sheng Wu

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

School of Packaging

1995

ABSTRACT

MOISTURE ABSORPTION CHARACTERISTICS
OF 100% RECYCLED CORRUGATED BOARD
By

Shu-Sheng Wu

The equilibrium moisture sorption isotherm was used for 100% recycled
corrugated board to predict its strength performances which were strongly
affected by its moisture content. An Oswin equation was successfully
applied to the equilibrium moisture sorption isotherm of 100% recycled
corrugated board. The results of this study further demonstrated the utility
of the linear regression model for describing the Oswin equation and the
relationship between strength performances and equilibrium moisture
content. The moisture content of 100% recycled corrugated board was
found to have an inverse effect on edge crush strength, flat crush resistance
and bursting strength. From the resulting linear regression equations, the
edge crush strength and flat crush resistance can be successfully predicted
under any relative humidity (between 0% and 100%) and at three
temperatures (5, 20, and 40 °C).

DEDICATION

This thesis is dedicated to my mother, whose patience and support made

this accomplishment possible.

iii

ACKNOWLEDGEMENTS

I would like to thank my major professor Dr. J. Lee for his valuable
advice and guidance through the graduate program. I also thank Dr. G.
Burgess and Dr. R. Brandenburg for serving on my committee. Their
counsel and guidance are gratefully acknowledged.

I also wish to thank Mrs. D. Schmidt and Dr. P. Schmidt for their
patience to revise my thesis. Through their efforts the completion of this

thesis has been possible.

iv

TABLE OF CONTENTS

Page
LIST OF TABLES .............................................................................. vii
LIST OF FIGURES .............................................................................. xiii
INTRODUCTION .............................................................................. 1
LITERATURE REVIEW ........ 4
1. Corrugated Board ......................................................................... 4
2. The Effect of Recycled Fiber on Paperboard Properties .............. 5
3. The Effect of Moisture Content on Corrugated Board ................... 6
4. Equilibrium Vapor Sorption Isotherm ......................................... 9
4.1 Water activity ........................................................................... 9
4.2 Equilibrium moisture content ................................................... 10
4.3 Temperature effect .................................................................... 10
4.4 Mathematical models for the equilibrium vapor sorption
isotherm ..................................................................................... 11
5. Development of a Theoretical Model for the Compressive Strength
of Corrugated Fiberboards ............................................................ 14
6. Papermaking Factors Affecting Box Properties ........................... 17
6.1 Liner/medium weight relationships .......................................... 17
6.2 Fluting process .......................................................................... 17
6.3 Glueability at the corrugator ..................................................... 19
6.4 Press drying .............................................................................. 20
7. Edgewise Compressive Strength .................................................. 21
8. Bursting Strength .......................................................................... 23
9. Flat Crush Resistance ................................................................... 24
MATERIALS AND METHODS ......................................................... 25
Test Materials .................................................................................... 25
Conditioning ...................................................................................... 26
Test Methods ..................................................................................... 28
Moisture Sorption Isotherm .............................................................. 29

Edge Crush Testing ........................................................................... 3O
Bursting Strength Testing ................................................................. 30
Flat Crush Testing ............................................................................. 30
RESULTS AND DISCUSSION ........... . ............................................... 32
Equilibrium Moisture Content (EMC) ............................................. 32
Moisture Sorption Isotherm .............................................................. 32
‘Edge Crush Strength (under Saturated Salt Solutions’ Conditions)
versus Equilibrium Moisture Content ............................................... 47
Flat Crush Resistance (under Saturated Salt Solutions’ Conditions)
versus Equilibrium Moisture Content ............................................... 58
Strength Performances under Recommended ASTM Conditions 58
Linear Regression Equations to Re-build the Data ........................... 59
CONCLUSIONS AND FUTURE RESEARCH .................................. 75
APPENDICES ...................................................................................... 77
Appendix A: Equilibrium Moisture Content .................................... 77
Appendix B: Edge Crush Strength ................................................... 92
Appendix C: Flat Crush Resistance .................................................. 110
Appendix D: Bursting Strength ........................................................ 128
Appendix E: Linear Regression Model for Re-building Data ......... 131
BIBLIOGRAPHY ................................................................................. 1 3 4

vi

LIST OF TABLES

Table Page
1 Equilibrium relative humidities (RH) for saturated salt solutions at
different temperatures ................................................................. 27
2 EMC vs. RH and Aw for Board 1 ................................................ 33
3 EMC vs. RH and Aw for Board 2 ............................................... 34
4 EMC vs. RH and Aw for Board 3 ............................................... 35
5 Ln EMC vs. Ln (Aw/ l-Aw) for Board 1 ................................... 4O
6 Ln EMC vs. Ln (Aw/ l-Aw) for Board 2 ................................... 41
7 Ln EMC vs. Ln (Aw/ l-Aw) for Board 3 ........ 42
8 Linear Regression for Ln EMC vs. Ln (Aw/ l-Aw) ................... 46
9 Edge Crush Strength vs. EMC and RH for Board 1 .................... 51
10 Edge Crush Strength vs. EMC and RH for Board 2 ...................... 52
11 Edge Crush Strength vs. EMC and RH for Board 3 ...................... 53
12 Linear Regression for Edge Crush Strength vs. EMC .................. 57
13 Flat Crush Resistance vs. EMC and RH for Board 1 ................... 64
14 Flat Crush Resistance vs. EMC and RH for Board 2 ................... 65
15 Flat Crush Resistance vs. EMC and RH for Board 3 ................... 66
16 Linear Regression for Flat Crush Resistance vs. EMC ................ 7O
17 Strength under Recommended ASTM Conditions ....................... 71
A-l Equilibrium Moisture Content of Board 1 at T=40°C, RH=1 1.6%.. 77
A-2 Equilibrium Moisture Content of Board 1 at T=40°C, RH=32.1%.. 77
A-3 Equilibrium Moisture Content of Board 1 at T=40°C, RH=49.2%.. 77
A-4 Equilibrium Moisture Content of Board 1 at T=40°C, RH=75.4%.. 78
A-5 Equilibrium Moisture Content of Board 1 at T=40°C, RH=87.9%.. 78
A-6 Equilibrium Moisture Content of Board 2 at T=40°C, RH=11.6%.. 78
A—7 Equilibrium Moisture Content of Board 2 at T=40°C, RH=32.1%.. 79
A-8 Equilibrium Moisture Content of Board 2 at T=40°C, RH=49.2%.. 79
A-9 Equilibrium Moisture Content of Board 2 at T=40°C, RH=75.4%.. 79

A-lO Equilibrium Moisture Content of Board 2 at T==40°C, RH=87.9%.. 80
A-ll Equilibrium Moisture Content of Board 3 at T=40°C, RH=11.6%.. 8O
A-12 Equilibrium Moisture Content of Board 3 at T=40°C, RH=32.1%.. 80
A-13 Equilibrium Moisture Content of Board 3 at T=40°C, RH=49.2%.. 81
A-14 Equilibrium Moisture Content of Board 3 at T=40°C, RH=75.4%.. 81
A-15 Equilibrium Moisture Content of Board 3 at T=40°C, RH=87.9%.. 81

vii

Table Page
A-l6 Equilibrium Moisture Content of Board 1 at T=20°C, RH=12.4%.. 82
A-17 Equilibrium Moisture Content of Board 1 at T=20°C, RH=33.6%.. 82
A-18 Equilibrium Moisture Content of Board 1 at T=20°C, RH=54.9%.. 82
A-19 Equilibrium Moisture Content of Board 1 at T=20°C, RH=75.5%.. 83
A-20 Equilibrium Moisture Content of Board 1 at T=20°C, RH=93.2%.. 83
A-21 Equilibrium Moisture Content of Board 2 at T=20°C, RH=12.4%.. 83
A-22 Equilibrium Moisture Content of Board 2 at T=20°C, RH=33.6%.. 84
A-23 Equilibrium Moisture Content of Board 2 at T=20°C, RH=54.9%.. 84
A-24 Equilibrium Moisture Content of Board 2 at T=20°C, RH=75.5%.. 84
A-25 Equilibrium Moisture Content of Board 2 at T=20°C, RH=93.2%.. 85
A-26 Equilibrium Moisture Content of Board 3 at T=20°C, RH=12.4%.. 85
A-27 Equilibrium Moisture Content of Board 3 at T=20°C, RH=33.6%.. 85
A-28 Equilibrium Moisture Content of Board 3 at T=20°C, RH=54.9%.. 86
A-29 Equilibrium Moisture Content of Board 3 at T=20°C, RH=75.5%.. 86
A-30 Equilibrium Moisture Content of Board 3 at T=20°C, RH=93.2%.. 86
A-31 Equilibrium Moisture Content of Board 1 at T=5°C, RH=14.0%.... 87
A-32 Equilibrium Moisture Content of Board 1 at T=5°C, RH=34.6%.... 87
A-33 Equilibrium Moisture Content of Board 1 at T=5°C, RH=59.2%.... 87
A-34 Equilibrium Moisture Content of Board 1 at T=5°C, RH=75. 1%.... 88
A-35 Equilibrium Moisture Content of Board 1 at T=5°C, RH=96.6%.... 88
A-36 Equilibrium Moisture Content of Board 2 at T=5°C, RH=14.0%.... 88
A-37 Equilibrium Moisture Content of Board 2 at T=5°C, RH=34.6%.... 89
A-38 Equilibrium Moisture Content of Board 2 at T=5°C, RH=59.2%.... 89
A-39 Equilibrium Moisture Content of Board 2 at T=5°C, RH=75. 1%.... 89
A-4O Equilibrium Moisture Content of Board 2 at T=5°C, RH=96.6%.... 9O
A-41 Equilibrium Moisture Content Of Board 3 at T=5°C, RH=14.0%.... 9O
A-42 Equilibrium Moisture Content of Board 3 at T=5°C, RH=34.6%.... 90
A-43 Equilibrium Moisture Content of Board 3 at T=5°C, RH=59.2%.... 91
A-44 Equilibrium Moisture Content of Board 3 at T=5°C, RH=75.1%.... 91
A-45 Equilibrium Moisture Content of Board 3 at T=5°C, RH=96.6%.... 91

3-] Edge Crush Strength of Board 1 at T=5°C, RH=14.0% ............... 92
B-2 Edge Crush Strength of Board 1 at T=5°C, RH=34.6% ............... 92
B-3 Edge Crush Strength of Board 1 at T=5°C, RH=59.2% ............... 92
B4 Edge Crush Strength Of Board 1 at T=5°C, RH=75.1% ............... 93
B-S Edge Crush Strength of Board 1 at T=5°C, RH=85.0% ............... 93
B-6 Edge Crush Strength of Board 1 at T=5°C, RH=96.6% ............... 93

B-7 Edge Crush Strength of Board 2 at T=5°C, RH=14.0% ............... 94

viii

Table Page

B-8 Edge Crush Strength of Board 2 at T=5°C, RH=34.6% ............... 94
B-9 Edge Crush Strength of Board 2 at T=5°C, RH=59.2% ............... 94
B-10 Edge Crush Strength Of Board 2 at T=5°C, RH=75. 1% ............... 95
B-ll Edge Crush Strength of Board 2 at T=5°C, RH=85.0% ............... 95
B-12 Edge Crush Strength of Board 2 at T=5°C, RH=96.6% ............... 95
B-13 Edge Crush Strength of Board 3 at T=5°C, RH=14.0% ............... 96
B-14 Edge Crush Strength of Board 3 at T=5°C, RH=34.6% ............... 96
B-15 Edge Crush Strength of Board 3 at T=5°C, RH=59.2% ............... 96
B-16 Edge Crush Strength of Board 3 at T=5°C, RH=75.1% ............... 97
3-17 Edge Crush Strength of Board 3 at T=5°C, RH=85.0% ............... 97
8-18 Edge Crush Strength of Board 3 at T=5°C, RH=96.6% ............... 97
B-l9 Edge Crush Strength of Board 1 at T=20°C, RH=12.4% .......... 98
B-20 Edge Crush Strength of Board 1 at T=20°C, RH=33.6% ............. 98
B-21 Edge Crush Strength of Board 1 at T=20°C, RH=54.9% ............. 98
B-22 Edge Crush Strength of Board 1 at T=20°C, RH=75.5% ............. 99
B-23 Edge Crush Strength of Board 1 at T=20°C, RH=85.0% ............. 99
B-24 Edge Crush Strength of Board 1 at T=20°C, RH=93.2% ............. 99
B-25 Edge Crush Strength of Board 2 at T=20°C, RH=12.4% ............ 100
B-26 Edge Crush Strength of Board 2 at T=20°C, RH=33.6% ............ 100
B-27 Edge Crush Strength of Board 2 at T=20°C, RH=54.9% ............ 100
B-28 Edge Crush Strength of Board 2 at T=20°C, RH=75.5% ............ 101
B-29 Edge Crush Strength of Board 2 at T=20°C, RH=85.0% ............ 101
B-30 Edge Crush Strength of Board 2 at T=20°C, RH=93.2% ............ 101
B-31 Edge Crush Strength of Board 3 at T=20°C, RH=12.4% ............ 102
B-32 Edge Crush Strength of Board 3 at T=20°C, RH=33.6% ............ 102
8-33 Edge Crush Strength Of Board 3 at T=20°C, RH=54.9% ............ 102
B-34 Edge Crush Strength of Board 3 at T=20°C, RH=75.5% ............ 103
B-35 Edge Crush Strength of Board 3 at T=20°C, RH=85.0% ' ............ 103
B-36 Edge Crush Strength of Board 3 at T=20°C, RH=93.2% ............ 103
B-37 Edge Crush Strength of Board 1 at T=40°C, RH=11.6% ............ 104
B-38 Edge Crush Strength of Board 1 at T=40°C, RH=32.1% ............ 104
B-39 Edge Crush Strength of Board 1 at T=40°C, RH=49.2% ............ 104
B-40 Edge Crush Strength of Board 1 at T=40°C, RH=75.4% ............ 105
B-41 Edge Crush Strength of Board 1 at T=40°C, RH=85.0% ............ 105
B-42 Edge Crush Strength of Board 1 at T=40°C, RH=87.9% ............ 105
B-43 Edge Crush Strength of Board 2 at T=40°C, RH=11.6% ............ 106
B-44 Edge Crush Strength of Board 2 at T=40°C, RH=32.1% ............ 106

ix

Table Page

B-45 Edge Crush Strength of Board 2 at T=40°C, RH=49.2% ............ 106
B—46 Edge Crush Strength of Board 2 at T=40°C, RH=75.4% ............ 107
B-47 Edge Crush Strength of Board 2 at T=40°C, RH=85.0% ............ 107
B-48 Edge Crush Strength of Board 2 at T=40°C, RH=87.9% ............ 107
B-49 Edge Crush Strength of Board 3 at T=40°C, RH=11.6% ............ 108
B-50 Edge Crush Strength of Board 3 at T=40°C, RH=32.1% ............ 108
B-51 Edge Crush Strength of Board 3 at T=40°C, RH=49.2% ............ 108
8-52 Edge Crush Strength of Board 3 at T=40°C, RH=75.4% ............ 109
B-53 Edge Crush Strength of Board 3 at T=40°C, RH=85.0% ............ 109
B-S4 Edge Crush Strength of Board 3 at T=40°C, RH=87.9% ............ 109
C-1 Flat Crush Resistance of Board 1 at T=5°C, RH=14.0% ............ 110
C-2 Flat Crush Resistance of Board 1 at T=5°C, RH=34.6% ......... 110
C-3 Flat Crush Resistance of Board 1 at T=5°C, RH=59.2% ............ 110
C-4 Flat Crush Resistance of Board 1 at T=5°C, RH=75.1% ............ 111
C-5 Flat Crush Resistance of Board 1 at T=5°C, RH=85.0% ............ 111
C-6 Flat Crush Resistance of Board 1 at T=5°C, RH=96.6% ............ 111
C-7 Flat Crush Resistance of Board 2 at T=5°C, RH=14.0% ............ 112
C-8 Flat Crush Resistance of Board 2 at T=5°C, RH=34.6% ............ 112
C-9 Flat Crush Resistance of Board 2 at T=5°C, RH=59.2% ............ 112
C-lO Flat Crush Resistance Of Board 2 at T=5°C, RI—I=75.1% ............ 113
C-11 Flat Crush Resistance of Board 2 at T=5°C, RH=85.0% ............ 113
C-12 Flat Crush Resistance of Board 2 at T=5°C, RH=96.6% ............ 113
C-13 Flat Crush Resistance of Board 3 at T=5°C, RH=14.0% ............ 114
C-14 Flat Crush Resistance of Board 3 at T=5°C, RH=34.6% ............ 114
C-lS Flat Crush Resistance of Board 3 at T=5°C, RH=59.2% ............ 114
C-l6 Flat Crush Resistance of Board 3 at T=5°C, RH=75. 1% ............ 115
C-17 Flat Crush Resistance of Board 3 at T=5°C, RH=85.0% ............ 115
C-1 8 Flat Crush Resistance of Board 3 at T=5°C, RH=96.6% ............ 115
C-19 Flat Crush Resistance of Board 1 at T=20°C, RH=12.4% ............ 116
C-20 Flat Crush Resistance of Board 1 at T=20°C, RH=33.6% ............ 116
021 Flat Crush Resistance of Board 1 at T=20°C, RH=54.9% ............ 116
C-22 Flat Crush Resistance of Board 1 at T=20°C, RH=75.5% ............ 117
C-23 Flat Crush Resistance of Board 1 at T=20°C, RH=85.0% ............ 117
C-24 Flat Crush Resistance of Board 1 at T=20°C, RH=93.2% ............ 117
C-25 Flat Crush Resistance of Board 2 at T=20°C, RH=12.4% ............ 118
C-26 Flat Crush Resistance of Board 2 at T=20°C, RH=33.6% ............ 118
C-27 Flat Crush Resistance of Board 2 at T=20°C, RH=54.9% ............ 118

X

Table Page

C-28 Flat Crush Resistance of Board 2 at T=20°C, RH=75.5% ............ 119
C-29 Flat Crush Resistance of Board 2 at T=20°C, RH=85.0% ............ 119
C-30 Flat Crush Resistance of Board 2 at T=20°C, RH=93.2% ............ 119
C-31 Flat Crush Resistance of Board 3 at T=20°C, RH=12.4% ............ 120
C-32 Flat Crush Resistance of Board 3 at T=20°C, RH=33.6% ............ 120
C-33 Flat Crush Resistance of Board 3 at T=20°C, RH=54.9% ............ 120
C-34 Flat Crush Resistance Of Board 3 at T=20°C, RH=75.5% ............ 121
C-35 Flat Crush Resistance of Board 3 at T=20°C, RH=85.0% ............ 121
C-36 Flat Crush Resistance of Board 3 at T=20°C, RH=93.2% ............ 121
C-37 Flat Crush Resistance of Board 1 at T=40°C, RH=11.6% ............ 122
C-38 Flat Crush Resistance of Board 1 at T=40°C, RH=32.1% ............ 122
C-39 Flat Crush Resistance of Board 1 at T=40°C, RH=49.2% .......... 122
C-40 Flat Crush Resistance of Board 1 at T=40°C, RH=75.4% ............ 123
C-41 Flat Crush Resistance of Board 1 at T=40°C, RH=85.0% ............ 123
C-42 Flat Crush Resistance of Board 1 at T=40°C, RH=87.9% ............ 123
C-43 Flat Crush Resistance of Board 2 at T=40°C, RH=11.6% ............ 124
C-44 Flat Crush Resistance of Board 2 at T=40°C, RH=32. 1% ............ 124
C-45 Flat Crush Resistance of Board 2 at T=40°C, RH=49.2% ............ 124
C-46 Flat Crush Resistance of Board 2 at T=40°C, RH=75.4% ............ 125
C—47 Flat Crush Resistance of Board 2 at T=40°C, RH=85.0% ............ 125
C-48 Flat Crush Resistance Of Board 2 at T=40°C, RH=87.9% ............ 125
C-49 Flat Crush Resistance of Board 3 at T=40°C, RH=11.6% ............ 126
C-SO Flat Crush Resistance of Board 3 at T=40°C, RH=32.1% ............ 126
OS] Flat Crush Resistance of Board 3 at T=40°C, RH=49.2% ............ 126
C-52 Flat Crush Resistance of Board 3 at T=40°C, RH=75.4% ............ 127
C-53 F lat Crush Resistance of Board 3 at T=40°C, RH=85.0% ............ 127
C-54 Flat Crush Resistance of Board 3 at T=40°C, RH=87.9% ............ 127
D—l Bursting Strength Of Board 1 at T=5°C, RH=85% ..................... 128
D-2 Bursting Strength of Board 1 at T=20°C, RH=85% ..................... 128
D3 Bursting Strength of Board 1 at T=40°C, RH=85% ..................... 128
D4 Bursting Strength of Board 2 at T=5°C, RH=85% ..................... 129
D-5 Bursting Strength of Board 2 at T=20°C, RH=85% ..................... 129
D-6 Bursting Strength of Board 2 at T=40°C, RH=85% ..................... 129
D-7 Bursting Strength of Board 3 at T=5°C, RH=85% ..................... 130
D-8 Bursting Strength of Board 3 at T=20°C, RH=85% ..................... 130
D-9 Bursting Strength of Board 3 at T=40°C, RH=85% ..................... 130

E-l Linear Regression Model for Calculating the ECS and FCR of

xi

Table Page

Board 1 at 40°C ............................................................................. 131
E-2 Linear Regression Model for Calculating the ECS and FCR of

Board 1 at 20°C ............................................................................. 131
E-3 Linear Regression Model for Calculating the ECS and FCR of

Board 1 at 5°C ............................................................................. 131
E—4 Linear Regression Model for Calculating the ECS and FCR of

Board 2 at 40°C ............................................................................. 132
E-5 Linear Regression Model for Calculating the ECS and FCR of

Board 2 at 20°C ............................................................................. 132
E-6 Linear Regression Model for Calculating the ECS and F CR of

Board 2 at 5°C ............................................................................. 132
E7 Linear Regression Model for Calculating the ECS and FCR'of

Board 3 at 40°C ............................................................................. 133
E-8 Linear Regression Model for Calculating the ECS and FCR of

Board 3 at 20°C ............................................................................. 133
E—9 Linear Regression Model for Calculating the ECS and FCR of

Board 3 at 5°C ............................................................................. 133

xii

LIST OF FIGURES

Figure Page
1 Corrugated Board 1 Sorption Isotherm ........................................ 36
2 Corrugated Board 2 Sorption Isotherm ........................................ 37
3 Corrugated Board 3 Sorption Isotherm ........................................ 38
4‘ Ln EMC versus Ln (Aw/ l-Aw) for Board 1 .............................. 43
5 Ln EMC versus Ln (Aw/ l-Aw) for Board 2 .............................. 44
6 Ln EMC versus Ln (Aw/ l-Aw) for Board 3 .............................. 45
7 Edge Crush Strength of Board 1 .................................................. 48
8 Edge Crush Strength Of Board 2 ......................................... - ......... 49
9 Edge Crush Strength of Board 3 .................................................. 50
10 Edge Crush Strength of Board 1 .................................................. 54
11 Edge Crush Strength of Board 2 .................................................. 55
12 Edge Crush Strength of Board 3 .................................................. 56
13 Flat Crush Resistance of Board 1 ................................................ 61
14 Flat Crush Resistance of Board 2 ................................................ 62
15 Flat Crush Resistance Of Board 3 ................................................ 63
16 Flat Crush Resistance of Board 1 ................................................ 67
17 Flat Crush Resistance of Board 2 ................................................ 68
18 Flat Crush Resistance Of Board 3 ................................................ 69
19 Edge Crush Strength at Relative Humidity = 85% ..................... 72
20 Flat Crush Resistance at Relative Humidity = 85% ................... 73
21 Bursting Strength at Relative Humidity == 85% ......................... 74

xiii

INTRODUCTION

It is generally recognized that corrugated board is affected by both
moisture (or relative humidity) and temperature in the atmosphere. Since
corrugated board is made of cellulose fiber, which is highly hygroscopic, it
will readily absorb or desorb moisture within its environment. The rate of
water vapor gained or lost by corrugated board is proportional to the
difference of water vapor pressure existing inside the corrugated board and
in the atmosphere to which the corrugated board is exposed. The absorption
or desorption of water vapor by the corrugated board can be described by
the equilibrium vapor sorption isotherm. (or simply called moisture sorption
isotherm). Plotting equilibrium moisture content (EMC) versus equilibrium
relative humidity (or water activity) at a fixed temperature results in a
sigmoidal curve, which is the moisture sorption isotherm.

The moisture sorption isotherm is an extremely valuable tool for the food
scientist because it can be used to predict potential changes in food stability;
it can be used for packaging selection and for ingredient selection.
Similarly, it is also very valuable to apply the concept of moisture sorption
isotherm to corrugated boards, because it can be used to predict potential
change in strength performances (such as edgewise compressive (or edge
crush) strength, bursting strength, flat crush resistance, and so on); it can be
referred to for corrugated board selection. It is necessary to use a proper
mathematical equation to describe the moisture sorption isotherm of
corrugated boards. Some mathematical expressions which have been

developed for the moisture sorption isotherm of foods may properly be

2
chosen and applied to the moisture sorption isotherm of corrugated boards.

In this study, the linear regression was used to describe the moisture
sorption isotherm of corrugated board.

It is well known that the corrugated container plays an important role in
such things as protection, transportation, distribution, communication, and
warehouse storage. Since the corrugated container often suffers various
environmental and handling hazards, it should meet the minimum
requirements of railroads’ Uniform Freight Classification Rule 41 and
motor carriers’ National Motor Freight Classification Item 222 so that the
quality of its strength performance remains stable and therefore reduces
damage to the product inside. Rule 41 and Item 222 require that singlewall
corrugated fiberboard boxes have a minimum edge crush strength ranging
from 23 to 55 pounds per inch and a minimum bursting strength ranging
from 125 to 350 pounds per square inch, with a required minimum
combined weight of facings ranging fiom 52 to 180 pounds per 1000 square
feet allowing for a maximum weight of box and contents of 20 to 120
pounds (Fibre box handbook, 1992). Therefore, the standardization of the
corrugated shipping container is largely governed by the railroad and motor
carrier industry of the United States. The bursting strength, edge crush
strength, basis weight, box size, and product’s weight are all considered
when designing a corrugated box for a given product.

Due to the solid waste disposal problem, the use of recycled corrugated
board is gradually being supported by the freight industries. In general, the
use of recycled fiber from recycled corrugated board lowers the strength

properties of the resulting recycled corrugated container. Although recycled

3
fiber is not as strong as virgin fiber, it has been improved and thus

overcomes some of the loss in strength properties (Lumiainen, 1992).
Therefore, even though 100% recycled corrugated board generally has.
lower performance in strength properties, it is very important to construct
the moisture sorption isotherm of 100% recycled corrugated board in order
to (I) understand the relationships between relative humidity and
paperboard moisture content under different temperatures and (2) analyze
the relationships between paperboard moisture content and physical
properties of paperboard.

Therefore, the purpose of this study is: (l) to build up the moisture
absorption characteristics of 100% recycled corrugated board by using
moisture sorption isotherm, (2) to analyze the moisture sorption isotherm of
100% recycled corrugated board in terms of a mathematical equation, and
(3) to compare and analyze the edge crush, flat crush, and bursting strength
when the boards have different equilibrium moisture contents at different

relative humidities or temperatures.

LITERATURE REVIEW

1. Corrugated Board:

A corrugated board is composed of a fluted or corrugated medium layer
sandwiched between layers of linerboard. The corrugated (or fluted)
medium is usually manufactured from virgin hardwoods and recycled
corrugated containers by a semi-chemical process. Most linerboard is
produced from softwoods by the krafi or sulfate process. The hardwoods
and the recycling process provide shorter fibers than the softwoods. The
longer fibers produced from softwoods result in stronger linerboard.
Corrugated medium, because of its short, stiff fibers and good formation,
has three functions : (1) to space and stabilize the linerboard materials, (2)
to provide resistance to crushing of the combined board, and (3) to
contribute compressive strength and flat-crush strength to the corrugated
container made from the combined board (Kellicutt, 1972). Corrugated
board may be formed into singlewall, doublewall, or triplewall combined
board.

Old corrugated containers (OCC) can be recycled, composted,
incinerated, or landfilled (Miller, 1992). Recycling corrugated boards can
reduce disposal costs, help alleviate solid waste by saving space in landfills,
and diminish the need for virgin fiber. (Edwards, 1990; Kishbaugh, 1990;
Wray & Mulligan, 1992). Corrugated boards provide a high per-pound
heating value of 7047 BTU (British thermal unit), thereby serving as clean
fuel to help burn other products (Miller, 1992 and Fibre box handbook,

5
1992). OCC can be composted or landfilled because they are biodegradable

and environmentally friendly.

2. The Effect Of Recycled Fiber On Paperboard Properties:

The recycling process tends to shorten the long fibers in linerboard as Old
boxes are re-pulped (Fibre box handbook, 1992). The swelling and bonding
ability of fibers is reduced every time they pass through the papermaking
process (Lumiainen, 1992). Because of shorter and reduced bonding-ability
fibers, recycled fibers provide less flexibility and lower strength than virgin
fibers. In general, the use of recycled materials lowers the strength
properties of the resulting recycled paperboard and corrugated containers.
These reductions in strength properties can, to a large extent, be avoided by
further refining of the recycled fibers (Koning and Godshall, 1975).
Because refining creates fibrils needed for good fiber bonding, the recycled
fibers have improved natural bonding ability and thus overcome some of the
loss in strength properties of the recycled paperboard and corrugated
containers (Lumiainen, 1992).

Due to the production of shorter fibers and debris, increased refining can
decrease the drainage rate on the paper machine and thus reduce the
production rate (Kroeschell, 1992). Koning and Godshall also concluded
that recycled fiber from corrugated fiberboard drains more slowly on the
paper machine. Furthermore, due to the creation of less flexible and shorter
fibers after repeated recycling, the medium becomes more susceptible to
cracking on the corrugator (Koning and Godshall, 1975). This grade of

OCC is yellowish in color and weaker than other forms of corrugated board

6
(Miller, 1992). The greatest loss in strength occurs with the first recycling

of virgin material, rather than during subsequent recycling (Koning and
Godshall, 1975).

Using Recycled clean corrugated fiberboard reduces such properties as
flat crush, burst, and compressive strength -- reductions which generally
increase as the percentage of recycled fiber increases (Fahey and Bonnett,
1982). The best quality of recycled board is achieved when the recycled
material is old corrugated containers (OCC) and the ratio of virgin kraft to
recycled materials is in the neighborhood of 80:20 (Huck, 1991). Today,
most corrugated board manufacturers use 100% OCC to produce 100%
recycled medium and use a mixture of OCC and double-lined kraft (DLK)
cuttings to manufacture linerboard. In general, corrugated paperboard made

of 100% recycled fibers has lower performance in strength properties.

3. The Effect Of Moisture Content On Corrugated Board:

The main ingredient of paper or paperboard is cellulose, which is highly
hydroscopic and is affected by the moisture in the atmosphere. Normally,
the physical properties of a substance vary greatly, depending on its precise
moisture content. Therefore, the relationship between paper’s physical
properties and its moisture content is of primary importance.

The moisture content of paperboard is strongly related to the humidity
and temperature of the atmosphere. Variations in humidity and temperature
cause the paperboard to vary in moisture content. There is also a direct
relationship between the vapor pressure surrounding the paperboard and the

paperboard’s moisture content : “When the vapor pressure outside the

7
paperboard is greater than that inside the paperboard, water vapor tends to

be driven inside and the paperboard is likely to absorb the excess moisture.
When the vapor pressure inside is greater than that outside, water vapor
tends to be driven out and the paperboard is likely to lose moisture. When
there is no further exchange of moisture between paperboard and its
environment, the paperboard and its environment are said to be in
equilibrium.” (Singh, winter 1992).
Since the water vapor pressure at a given temperature is determined by
P = Psat X RH % V (1)
where P : vapor pressure

Psat : saturated vapor pressure at a given temperature

RH % : relative humidity
and Psat is directly affected by temperature changes, a relationship also can
be found between relative humidity and moisture content. The graph of
moisture content versus relative humidity under equilibrium conditions at a
fixed temperature is the Equilibrium Vapor Sorption Isotherm.

Benson (1971) carried out a study of the “effects of relative humidity and
temperature on tensile stress-strain properties of kraft linerboar ”. He used
the specimen equilibrium moisture content (EMC) instead of relative
humidity to show the relationship with tensile properties. His results
showed that when the EMC increased, the tensile properties decreased and
when the temperature increased, the EMC decreased and thus the tensile
properties increased. He also concluded that the effects of temperature on
tensile properties consist of two factors: (1) At any given level of RH,

temperature change causes a change in the level of absolute water vapor

8
available to the paper, a change in the absolute vapor pressure acting on the

paper, and a resulting change in the paper EMC. (2) Temperature changes
directly affected the behavior of paper subject to an external stress through
changes in thermal energy levels.

Ievans (1977) indicated that the corrugated board equilibrium moisture
content is directly related to the ambient % RH and affects the stacking
strength of palletized corrugated boxes. Kellicutt (1959) also showed that as
the moisture content decreases, the paperboard box’s compressive strength
increases. He developed the equation below:

CS = CS0 x 10'3'01M (2)
where CS : compressive strength of box (lbs)
CSO : compressive strength at 0 percent moisture content
M : moisture content (grams H20/ 100 grams dry board)
Normally, the moisture content existing in paperboard is in the
neighborhood of 6%. Increasing moisture content lowers the compressive
strength of paperboard boxes and weakens the paperboard.

Because the moisture content in the paperboard box affects the
compressive or stacking strength of paperboard box, it also can influence
the box life span. The moisture content is dependent on the fluctuations in
humidity and temperature in the real world. According to Boonyasarn’s
study (1990), he demonstrated even though two types of corrugated
fiberboard containers perform similarly in a non-cyclic environment, one
may fail before the other in a cyclic environment. That means one box type
may lose its compression strength greater or faster than the other under the

cyclic environment. Leake and Wojcik (1993) demonstrated that boxes

9
subjected to changing humidity while under load have a shorter life span

than those exposed to a constant environment and that the greater the
moisture change, the shorter the life span. They also pointed out that the
shortening of a box’s life span caused by a fluctuating environment is not
simply a laboratory-induced phenomenon, but occurs in the real world of

warehousing and transportation.

4. Equilibrium Vapor Sorption Isotherm:

In describing an equilibrium vapor sorption isotherm, the concepts of
water activity (or equilibrium relative humidity), equilibrium moisture
content (EMC), and temperature are very important. Plotting EMC versus
equilibrium relative humidity (or water activity) at a fixed temperature
results in a sigmoidal curve, which is the equilibrium vapor sorption

isotherm.

4.1 Water activity:
The water activity, Aw, is defined as:
Aw=%ERH/100=P/Psat (3)
where ERH : equilibrium relative humidity

P : vapor pressure

Psat : saturated vapor pressure at a given temperature
The water activity of a moisture-sensitive product at various moisture
contents and temperatures will determine whether this product will gain or
lose moisture when exposed to a surrounding environment. In general, at a

constant moisture content in the moisture-sensitive product, Aw increases

10
with increasing temperature (Labuza, 1984). Both chemical reaction rate

and microbial activity are directly controlled by Aw (Labuza, 1970). An
increase in Aw can result in an increase in reaction rate, which leads to the
quality loss of a product. The degree of binding of water also has an effect
on the quality of a product. The more tightly water is bound, the lower its

Aw (Labuza, 1984).

4.2 Equilibrium moisture content:

The EMC is defined as the moisture content of a product has come to
equilibrium with the moisture of the surrounding environment. Water
directly interacts with a product through dipole-dipole forces, ionic bonds
(H3O+ or OH), Van Der Walls forces (hydrophobic bond), or the hydrogen
bond (Labuza, 1984). These water molecules, if tightly bound to the
product, require extra energy to be transferred from the liquid into the vapor
state and thus are less free to the vapor, resulting in reduced Aw (equation
3). When the vapor pressure inside the product is equal to that outside the
product, it is said to be in equilibrium and the EMC of the product is

therefore reached.

4.3 Temperature effect:

Because of the nature of water bonding, at constant Aw, moisture-
sensitive products hold less water at higher temperatures than at lower ones.
The effect of temperature follows the Clausius-Clapeyron equation (Labuza,
1984):

lnAw2/Aw1=QsX(1/T1-1/T2)/R (4)

1 l
where Awl : water activity at temperature T1 °K

Aw2 : water activity at temperature T2 °K

Qs : heat of sorption in cal/mole (function of moisture content)

R : gas constant (1.987 cal/mole°K)
If the corresponding heat of sorption is known at constant moisture content,
the Clausius-Claypeyron equation can be used to predict the isotherm Aw
value at any temperature. To determine Qs, the sorption isotherm must be
measured for at least two temperatures. The Qs does not change with
temperature. Generally, Qs increases with decreasing moisture content,

indicating a stronger interaction energy.

4.4 Mathematical models for the equilibrium vapor sorption isotherm:

It is necessary to develop a mathematical expression model of the
equilibrium vapor sorption isotherm. As with any mathematical model, care
should be taken in giving it any physical meaning, and one should
understand the limitations of the data. Several commonly used mathematical

expressions are showed below:

The B‘.E.T. (Brunauer-Emmett-Teller) equation (Labuza, 1984; Giacin
and Downes, spring 1993) is:
Aw/ [(l-Aw)M] = 1 /(MC) + [(C-1)Aw] / (MOC) (5)
where Aw : water activity
M : moisture content (dry weight basis) at Aw and temperature T
C : constant

M0 : monolayer value

12
The monolayer value, which is usually around an Aw of 0.2-0.4, has the

lowest rate of most deteriorative reactions in food systems (Salwin, 1959).
An increase in Aw beyond this region (0.2-0.4) can result in an increase rate
by a factor of 50-100% for each 0.1 Aw change (Labuza, Kaanane, and
Chen, 1985). For most dry foods, an increase in Aw by 0.1 unit in this
region decreases shelf life two to three times. Below this range, the quality
loss happens (Lauza, 1984). Therefore, this monolayer value can be viewed

as critical Aw value, which is related to the quality control of a product.

The GAB (Guggenheim-Anderson-de Boer) equation (Labuza, 1984)
was found to fit many hundreds of food isotherms. The equation has the
form:

M / M0 = ClKAw/ [(l-KAw)(1-KAw+ClKAw)] (6)
where M : moisture content
M0 : monolayer value
Cl, K : constants

Aw : water activity

The Hailwood and Horrobin equation (Labuza, 1984) is :
Aw / M = C1 + C2Aw + C3Aw2 (7)
where Aw : water activity

M : moisture content

C1, C2, C3 : constants

13

The linear equation (Chirife & Iglesias, 1978; Giacin & Downes, Spring

1993) is:
M = Aw x a + b
where M : moisture content
Aw : water activity
a : slope

b : intercept

The Oswin equation (Oswin, 1946) is:
M = C [Aw/(l-Aw)]n
where M : moisture content
C : constant
Aw : water activity

n : exponent

The Mizrahi equation (Mizrahi & Labuza, 1970) is:

Aw = (C1 +.M) / (C2 + M)
where Aw : water activity
C1, C2 : constants

M : moisture content

The Henderson equation (Henderson, 1952) is:
1 - Aw = exp [-CM"]
where Aw : water activity

C : constant

(8)

(9)

(10)

(11)

l 4
M : moisture content

n : exponent

The Kuhn equation (Giacin & Downes, spring 1993) is:
M=Cl /(ln Aw)"+C2 (12)
where M : moisture content
C1, C2 : constants
Aw : water activity

n : exponent

5. Development Of A Theoretical Model For'The Compressive Strength Of
Corrugated Fiberboards:

Compression strength is a very important indicator of final box
performance. In order to design a box which performs well, it is necessary
to develop a theory to predict the expected compressive strength. The theory
developed by McKee, Gander, and Wachuta (1963) accounts for top-load
compression strength of corrugated boxes. Their theory is based on the
theory for the buckling of thin plates modified empirically to match
experimental data. Finally, an equation was developed to predict
compression strength. The equation is as follows:

P = 2.028 X Pm0.746 X ((Dny)l/2)0.254 X Z0.492 (13)
where P : container compressive strength, lb
Pm : edgewise compressive strength, lb/in.
Dx : flexural stiffness per unit width of combined board (machine

direction), lb-in.

15
Dy : flexural stiffness per unit width of combined board (cross-

machine direction), lb-in.

Z : container perimeter, in.
Because the flexural stiffness, which is a measure of the bending strength of
the combined board, is not easy to measure and can be simplified by finding
the correlation of composite flexural stiffness, edgewise compression
strength, and combined board caliper:

(Dny)”2 = 66.1 x Pm x H2 (14)
where H : board caliper, in.
Equation (13) can be modified as:
P = 5.87 x Pm x (211)“2 (15)
where P : container compressive strength, lb

Pm : edgewise compressive strength, lb/in.

Z : container perimeter, in.

H : board caliper, in.
According to Nordkvist’s study on optimizing fluting and liner proportions
(1988), the simplified equation (15) can be used with results as good as
equation (13). He also mentioned that due to the lack of reliable methods to
measure flexural stiffiress, flexural stiffiress can be substituted by the
thickness (or caliper) of corrugated board and thus equation (13) can be
modified as equation (15).

Because McKee’s equation (equation (15)) does not include the influence

of moisture content and is inadequate in the case of wrap-around boxes,
Kawanishi (1989) derived a statistical formula useful for estimating the

compression strength of a box based on its specifications. The specifications

16
are grade of corrugated fiberboard, size of box, type of box, printed area and

moisture content. The formula is:
F = 3.79 x 10'8 x K0379 x w“650 x w"2°
X (14.15 X y2.45 X t3.34 X Z0.565 X k'0'3’5
X Poosoz X Sam (16)
where F: compression strength of box (kgf)
K : liner type (3 for K liner, 2.5 for K’ liner, 2 for B liner; linerboard
average)
W : total basis weight of linerboard (g/mz)
w : total basis weight of corrugating medium (g/mz)
d : total corrugation ratio (1.59 for A-flute, 1.36 for B-flute, 1.27 for
E-flute, 2.59 for AB-flute)
y : average corrugation count (34 for A-flute, 50 for B-flute, 90 for
E-flute, 42 for AB-flute)
t : thickness of corrugated fiberboard sheet (mm)
Z : box perimeter (cm)
k : type of box (1 for A-l type = a regular slotted container, 2 for
wrap-around type)
P : printed ratio of box (1 for no print, 0.01 for solid print)
8 : moisture content of side wall
Equation (16) seems a little more complicated than equation (15).
Furthermore, equation (16) derived from its specifications can only be used
for a limited range--- A, B, E, and AB-flutes. However, equation (16) gives

better agreement with experimental results than equation (15) or (13).

l 7
6. Papermaking Factors Affecting Box Properties:

6.1 Liner/medium weight relationships:

According to Rule 41, the corrugating medium must not weigh less than
26 pounds per 1000 square feet. The main function of the corrugated
medium is to space the facings and to provide stability to prevent buckling
or crushing. Kellicutt (1972) indicated that 26 pounds per 1000 square feet
corrugating medium provides the stability necessary to develop all of the
inherent strength of the facings in double-faced corrugated board. Also the
weight of the corrugating medium required to develop all the inherent
strength of the facing material in double-faced corrugated is dependent on
the weight of that facing material. He also showed that compressive strength
values were higher when the combined board had (1) heavier facings, (2)
heavier mediums, or (3) both heavier facings and heavier mediums. That

means the higher the basis weight, the higher the compression strength.

6.2 Fluting process:

Fluting is a forming operation. The corrugating medium is formed into
the flute (or sinusoidal) contour when it is drawn into a nip created by two
gearlike corrugating rolls under certain stress, temperature, and moisture
Conditions. During fluting, the corrugated medium is exposed to relatively
high tensile, bending, shearing, and transverse compressive stresses to
enhance the fiber-to-fiber bonding and thus lower 40% of the machine
direction (MD) and 20% of the cross direction (CD) edgewise compressive

strength of the corrugating medium (Whitsitt and Sprague, 1987). In this

18
case, the reduction of compressive strength of the corrugated medium in

NH) and CD also will reduce the combined board’s performance in
compressive strength and flat crush strength.

In order to minimize the strength losses during fluting, there are two
approaches (Whitsitt and Baum, 1987) : One approach is to make more
effective use of preconditioning heat and steam, because preconditioning
alters the properties of the corrugating medium resulting in a medium which
has sustained less damage. The second approach is to alter the properties of
the base medium during its manufacture. This can be expressed as the
formula:

RR=1-(K/R)(Ex/EZ)“4(W/d) (17)
where RR : retention ratio, or the ratio of compressive strengths of
fluted to uncorrugated medium
Ex : MD Young’s modulus
Ez : out-of-plane Young’s modulus
W : basis weight V
d : density
R : radius of curvature of the fluting rolls
K : constant
It is clear that increasing the density of the corrugated medium increases the
retention ratio and thus improves both its edgewise crush strength and its
flat crush strength. Whitsitt and Baum also indicated that densification of
the corrugated medium by wet pressing pressure makes substantial
increases in the flat crush and edgewise crush strength of combined board

made from that corrugated medium.

19

6.3 Glueability at the corrugator:

The proper gluing of medium to linerboard is essential to box
performance. During the fluting process, medium and liner are combined to
form single-faced board in the single facer of the corrugator by first
applying adhesive to the flute tips and then immediately pressing the flute
tips against a preheated linerboard. Then, the single-faced board travels
along a bridge to the double backer, where adhesive is again applied to the
flute tips and a second preheated linerboard is pressed against the flute tips,
thus producing a combined board.

Due to the combination of thermal gelatinization and dehydration, the
starch adhesive develops a very strong bond between the medium and
linerboard (Lepoutre and Inoue, 1989). The gelatinization of the starch
adhesive, created by heating it over a temperature range, contributes to
increased viscosity and the development of strong bond strength. The
viscosity increases when the starch granules absorb water from the
surrounding gelatinized starch solution and swell enough to intensify the
' inter-granular friction strength. Leaving a layer of raw starch granules
separated at the surface of the board, the aqueous phase (gelatinized starch)
is absorbed by the board, and then provides the bond to hold fibers together.
When water molecules diffuse out of the wet adhesive into the board and
finally into the atmosphere, a strong permanent bond is formed between
board and adhesive.

Lorenz and Whitsitt (1990) concluded that the liner and medium

properties which may be expected to influence adhesion include wettability,

20
porosity, roughness, and density, in addition to the internal fiber bonding

strength of the sheet. They also indicated four properties which are
important for good bonding : (1) A porous surface which has many
uniformly distributed pore openings. (2) A rough surface which provides a
greater surface area for bonding than a smooth surface. (3) A surface which
is easily wet by an aqueous adhesive. (4) The strongest fiber-to-fiber bond

consistent with other properties.

6.4 Press drying:

Press drying is a papermaking technique used for drying paperboard webs
simultaneously with heat and pressure. Because heat and pressure increase
the fiber conformability and fiber bonding ability by promoting natural
polymer flow on the fiber surface (Horn, Bormett, and Setterholm, 1988),
press drying can provide more support for fiber-to-fiber bonding and
produce a much stronger linerboard and corrugating medium than
conventional drying (Horn and Bormett, 1985). Therefore, some physical
properties of paperboard will be improved after the press drying process.
Horn and Borrnett (1985) in their study, conventional and press dry of high-
yield paper birch for use in linerboard and corrugating medium, concluded
that press drying eliminated scoreline fracturing and increased burst
strength, flat crush, edge crush, compressive strength, and flexural stiffness,
but decreased impact resistance. The reason for decreased impact resistance
is the shorter fiber length and increased stiffness associated with these high
yield pulps. Also, the tear strength in birch linerboards also was found by

them to be lower than commercial pine linerboard. The reason is the

21
increased fiber-to-fiber bonding and the shorter fiber length of the birch

fiber.

Horn (1989) studied the factors affecting wet strength of press-dried
paperboard, and concluded that four press-drying variables were related to
the moisture resistance of handsheets made from high-yield hardwood kraft
pulp: (1) Pulp yield : Dry tensile strength was higher in sheets made from
lower-yield (59%) pulp, and wet tensile strength was higher in sheets made
from higher-yield (69%) pulp. The higher tensile strength can be attributed
to both the greater availability for bonding of hemicellulose on the fiber
surface and the lower lignin content for sealing the hemicellulose bonds.
The increase in wet strength is due primarily to lignin flow. (2) Pressing
pressure : Dry tensile strength increased 25% if pressing pressure increased
from 0.35 Mpa to 2.76 Mpa, and wet tensile strength was doubled if
pressing pressure increased from 0.35 Mpa to 5.52 Mpa. (3) Drying
temperature : Drying at 204 oC produced stronger sheets in dry and wet
strength than at 94 0C. (4) Drying time : At 204 0C, pressing for 10 minutes
produced over 300% higher wet strength than pressing for 30 seconds.
Therefore, drying time (nip residence time) is an important factor in

maximizing the wet tensile strength.

7. Edgewise Compressive Strength:
Edgewise compressive strength (ECT) is mainly dependent on the
compressive properties of the components of the combined board.

Kroeschell

22
(1992) showed that ECT must be largely determined by the strength of the

component linerboard and corrugated medium, since all of these variables,
adhesion, and combined board thickness have only minimal effect on ECT.
There are two ways to approach the relationship between ECT and
component characteristics (Whitsitt, 1988) : (1) To sum up the compressive
strengths of the components and allow for the draw of the corrugated
medium. (2) To treat combined board as a structure composed of (a) narrow
flat plate elements of liners between flute tops and (b) flat or curved plates
of medium. These miniature plate elements could become unstable,
buckling in the same way that a box panel buckles in top-load compression.
When such local buckling occurs, the combined board ECT is dependent on
the edgewise compression and bending properties of the liners and medium.

McKee et a1. (1963) indicated that edgewise compressive strength (ECT)
and flexural stiffness affect the top-load compressive strength performance
of a box (equation (13)). Therefore, the ECT is directly related to the box
compression strength. Generally, the higher the edgewise compression
resistance, the better the stacking properties of the box (Thielert, 1986).
Using ECT values, shippers can more accurately determine stacking
strength, optimizing warehouse and shipping performance at a lower cost
(Santelli, 1991). Whitsitt (1988) concluded that reducing the ratio of the
machine direction to the cross-machine direction of linerboard increased the
cross-machine direction compressive strength of liners and, hence, ECT. He
also showed that increasing the density of the linerboard and medium by
wet pressing increased the combined board ECT, though increased Wet

pressing decreased the thickness and bending stiffness of the liners.

23
In the ECT test, according to ASTM D 2808-69, the samples are cut into

2” X 1 l/ ” sizes and the edges of the samples are reinforced by
impregnating them with paraffin wax to prevent edge failure. The
rectangular sample of corrugated board is placed between the platens of the
crush tester and makes use of the two supporting blocks to hold the sample
(or flute direction) upright. The load is applied perpendicular to the flutes.
The greatest force that sample can bear without failure is the edge crush
value. Uneven sample cuts, samples which slip during testing, and

compression speed will affect the ECT values.

8. Bursting Strength:

The bursting strength is directly related to the combination of tensile
strength and stretch of sheet material. Therefore, burst strength is related to
the manner and rate of sheet formation and drying, sheet thickness, and
basis weight (McGee, 1985). In the burst test, the material is secured
between platens and is ruptured by an expanding rubber diaphragm which
the pressure rises from. The clamp pressure is the main variable that affects
the test results and reproducibility. A low clamp pressure causes corrugated
samples to slip and higher results will be read. A high pressure causes the
flutes of corrugated board to be crushed and lower values are produced. The
test yields a reproducibility that may vary from 10 to 25 percent. McGee
(1985) also showed that bursting strength tests are subject to more variation
than many other physical tests. The causes of variation are the differences in
fiber size, shape, and orientation, and interfiber bonding within the sheet, as

well as the complex stresses and strains created during testing.

24

9. Flat Crush Resistance:

Flat crush resistance is the ability of cOrrugated board to resist being
crushed when applying the crush force perpendicular to the surface of the
board. This crushing may occur in the printing operation, bundling
machines, and so on. The flat crush test value is most affected by the

thickness of the board and the strength and density of the medium.

MATERIALS AND METHODS

TEST MATERIALS:

There were three kinds of 100% recycled, C-flute (42 flutes/ft), and
single-wall corrugated fiberboards supplied by a commercial manufacturer
of corrugated packaging used in this study. The calipers of the three kinds
of fiberboards were all the same, 5/32 inches. Three different basis weights
(linerboard/medium/linerboard) (lb/1000 ftz) were used as described below:
Board 1: 34/26/34
Board 2: 50/26/50
Board 3: 67/26/67

Prior to conditioning and testing all test fiberboard materials were
preconditioned at 10 to 35% relative humidity and 22 to 40°C (American
Society for Testing and Materials (ASTM) D685-87) for a week. After that,
they were used to make test specimens for moisture content determination,
edge crush test, bursting strength test, and flat crush test. The number and

size of the samples were as follows:

1. Ten samples per temperature under each relative humidity of each
saturated salt solution condition (Table 1) were cut into 3” x 3” for each
type of board to determine their equilibrium moisture content. The total
number of samples was : 10 replications x 15 saturated salt solutions’

conditions x 3 board types = 450 samples.

25

26
2. Ten samples per temperature under each relative humidity condition were

cut into 1.25” wide x 2” long for each type of board for the edge crush test.
The flutes were parallel to the long axis of the test sample. The total number
of samples was : 10 replications x (3 ASTM conditions + 15 saturated salt

solutions’ conditions) x 3 board types = 540 samples.

3. Five board samples per temperature under each relative humidity
condition (except for saturated salt solutions’ conditions) were cut into 12”
x 12” for each type of board for the bursting strength test. The total number
of samples was : 5 replications x 3 ASTM conditions x 3 board types = 45

samples.

4. Ten circular samples per temperature under each relative humidity
condition were cut by circular sample cutter (TMI) into about a 10 square
inch area for each type of board for the flat crush test. The total number of
samples was : 10 replications x (3 ASTM conditions + 15 saturated salt

solutions’ conditions) x 3 board types = 540 samples.
CONDITIONING:

After making test specimens, the test samples of each board type were
brought to the following standardized conditions:
A. ASTM conditions:
1. Refrigerated storage condition: 5i2 0C and 85:5 %RH
2. Temperate high humidity condition: 20:2 °C and 8515 %RH

27
3. Tropical condition: 40:2 °C and 85:5 %RH

B. Saturated salt solutions’ conditions: see Table 1

Table 1. Equilibrium relative humidities (RH) for saturated salt solutions at

 

 

different temperatures
Saturated Salt Solutions 5°C 20°C 40°C
(%RH) (%RH) (%RH)

Lithium Chloride (LiCl.HzO) 14.0 12.4 11.6
Magnesium Chloride (MgC12.6HzO) 34.6 33.6 32.1
Magnesium Nitrate (Mg(NO3)2.6HzO) 59.2 54.9 49.2
Sodium Chloride (NaCl) 75.1 75.5 75.4
Potassium Nitrate (KNO3) 96.6 93.2 87.9

 

The temperatures and humidities for the refrigerated storage, temperate
high humidity, and tropical conditions follow the recommendations of
ASTM 4332-89. Environmental Chambers (Nor-Lake Scientific No.3 and
Chrysler Koppin refi'igerator) were used to maintain those conditions.
Under those conditions, the corrugated boards will reach equilibrium with
the atmospheres such that subsequent measurements of physical properties
can be done.

The values of the temperatures and humidities for the saturated salt

solutions’ conditions follow Wexler and Hasegawa’s study on the “Relative

28
Humidity-Temperature Relationships of Some Saturated Salt Solutions in

the Temperature Range 0 to 50 °C” (1954). Under the saturated salt
solutions’ conditions, the corrugated boards should be placed and kept in
those specific atmospheres until they reach equilibrium with those
atmospheres in order to determine the equilibrium moisture content of the
corrugated boards, construct the moisture sorption isotherms of the
corrugated boards, and measure the physical properties of the corrugated
boards which can then be compared to those measured under the
refrigerated storage, temperate high humidity, and tropical conditions.

In order to create the saturated salt solutions’ conditions, a series of
tightly closed 5 gallon plastic buckets was used. Those buckets were too
small to contain the 12” x 12” samples for bursting strength test. Therefore,
those samples could only be conditioned at refrigerated storage condition,
temperate high humidity condition, and tropical condition.

Two coolers, which also were conditioned at 5, 20, and 40 °C, were used
to protect the conditioned samples during the transfer fiom environmental

chambers to test equipment.

TEST METHODS:

Equilibrium Moisture Content (EMC) Determination:

The equilibrium moisture contents of the conditioned board samples
were determined in accordance with ASTM D644-89. The EMC determined
on a dry weight basis was calculated from the loss of weight of the sample

afier oven drying. The specimens were dried in 3 Precision Scientific P/S

29
Model 524 oven. The expression used to calculate the EMC is shown

below:
EMC = [(Wl-W2) / W2] X 100 (18)
where EMC : equilibrium moisture content (g water/ 100 g dry weight of
the corrugated board)

W1 : equilibrium weight before oven drying (g), or final weight of
corrugated board after equilibrium is reached in the conditioned
atmosphere

W2 : weight after oven drying or dry weight (g)

Moisture Sorption Isotherm:

In developing moisture sorption isotherm data, care was taken to insure
that the relative humidity buckets employed were maintained at constant
temperature and relative humidity. Sorption isotherms for each board type
were desired at 5, 20, and 40 °C. Three different temperatures could be
obtained by the Environmental Chambers (Nor-Lake Scientific No.3 and
Chrysler Koppin refrigerator). Different humidities at each temperature
were obtained by using saturated salt solutions (Table 1) in contact with an
excess of the solids (salt) phase. The moisture sorption isotherms
constructed in this study were determined by placing corrugated board
samples over the saturated salt solutions in a series of tightly closed 5 gallon
plastic humidity buckets, maintained at the three constant testing
temperatures. These samples were weighed every three or four days until no
change (gain or loss) in weight was observed. Since no weight change was

observed, it was assumed equilibrium had been reached.

' 30
With stirring, a saturated salt solution was prepared by adding distilled

water to the salt in a clean container which was put into a closed bucket.
The actual solution should be a slurry with excess crystals present. The
relative humidity within each bucket was occasionally monitored by a
hygrometer to assure constant relative humidity values were maintained.
Moisture sorption isotherms were obtained by plotting the average
equilibrium moisture content of the ten replicates versus relative humidity

at each of the testing temperatures.

Edge Crush Testing:

The edge crush values for the conditioned specimens were determined in
accordance with ASTM D2808-69. The specimens were tested on a Crush
Tester (Model No. 17-36) manufactured by Test Machines Incorporated
(TMI).

Bursting Strength Testing:

The bursting strength testing of the conditioned board specimens was
performed for each group of test samples in accordance with TAPPI 8100m-
80. There were four readings taken on each of the 5 specimens. The
specimens were tested on a Mullen Tester manufactured by Perkins

Holyoke.

Flat Crush Testing:

31
The flat crush values for the conditioned board specimens were

determined in accordance with TAPPI 808om-86. The specimens were

tested on a Crush Tester (Model No. 17-36) manufactured by TMI.

RESULTS AND DISCUSSION

Equilibrium Moisture Content (EMC):

The saturated salt solutions and oven drying method were utilized for
determination of the equilibrium moisture content of the corrugated board.
The saturated salt solutions were very useful in producing known relative
humidities. A drying temperature of 105 °C and a drying time of 2 hours
was used to provide a drying condition for the corrugated board. Tables A—l
to A—45 (see appendix A) present the EMC determinations of three different
boards under different conditions. The EMC provides an important

component for the moisture sorption isotherm.

Moisture Sorption Isotherm:

The sorption isotherms were obtained by plotting the equilibrium
moisture content (g water/ 100 g dry weight) on the Y axis vs. the
corresponding relative humidity (or water activity) on the X axis. Tables 2
to 4 show the data of equilibrium moisture content (EMC) vs. relative
humidity (RH) and water activity (Aw) for three different boards (board 1,
board 2, and board 3) under three different temperatures (5, 20, and 40 °C).
Figures 1 to 3 present graphically the moisture sorption data for board 1,
board 2, and board 3.

From figures 1 to 3, the moisture sorption isotherms are dependent on
temperature. It is clearly evident from those moisture sorption isotherms
that for a given moisture content an increase in temperature results in an

increase in the relative humidity (or water activity). Of concern to the

32

33

Table 2. EMC vs. RH and Aw for Board 1

 

Temperature = 40 °C :

EMC 3.44 5.36 6.80 9.70 14.17
RH (%) 11.6 32.1 49.2 75.4 87.9
Aw 0.116 0.321 0.492 0.754 0.879
Temperature = 20 °C :
EMC 4.72 7.12 8.65 11.96 19.64
RH (%) 12.4 33.6 54.9 75.5 93.2
Aw 0.124 0.336 0.549 0.755 0.932
Temperature = 5 °C :
EMC 6.72 9.11 10.65 14.23 23.79
RH (%) 14.0 34.6 59.2 75.1 96.6

Aw 0.14 0.346 0.592 0.751 0.966

 

34

Table 3. EMC vs. RH and Aw for Board 2

 

Temperature = 40 °C :

EMC 3.60 5.52 7.05 9.78 13.65
RH (%) 11.6 32.1 49.2 75.4 87.9
Aw 0.116 0.321 0.492 0.754 0.879
Temperature = 20 °C :
EMC 4.98 7.28 9.13 11.57 19.22
RH (%) 12.4 33.6 54.9 75.5 93.2
Aw 0.124 0.336 0.549 0.755 0.932
Temperature = 5 °C :
EMC 7.53 9.15 11.31 14.31 23.84
RH (%) 14.0 34.6 59.2 75.1 96.6

Aw 0.14 0.346 0.592 0.751 0.966

 

35

Table 4. EMC vs. RH and Aw for Board 3

 

Temperature = 40 °C :

EMC 3.18 5.14 6.89 9.96 13.69
RH (%) 11.6 32.1 49.2 75.4 87.9
Aw 0.116 0.321 0.492 0.754 0.879
Temperature = 20 °C :
EMC 4.86 7.16 9.13 11.50 19.34
RH (%) 12.4 33.6 54.9 75.7 93.2
Aw 0.124 0.336 0.549 0.757 0.932
Temperature = 5 °C :
EMC 7.61 9.26 11.75 14.70 23.83
RH (%) 14.0 34.6 59.2 75.1 96.6

Aw 0.14 0.346 0.592 0.751 0.966

 

Moisture Content (9 waternoo g dry weight}

01

25

M
O

01

10

36

Corrugated Board 1 Sorption Isotherm

 

 

 

 

Figure l

l I l 1 fi 1 l l I
+ :4013
- 0 22012 -
"2 5C
. “A: I l I L g 1 I l I
0 it] 20 30 40 50 50 70 80 90 100
Relative Humidity (%)

37

Corrugated Board 2 Sorption Isotherm

 

M
O

(:1

Moisture Content {9 wateritao g dry weight}

(11

 

 

 

I I I I l I I I I
+ 24013 -
o :2UC ”
": 5C

1 l 4 I l l l l I

10 20 30 40 50 60 1’0 80 90 100

Relative Humidity (1)

Figure 2

Moisture Content {9 waternoo g drfr weight}

25

M
O

15

10

U!

38

Corrugated Board 3 Sorption Isotherm

 

 

 

 

Figure 3

I I I f I T I I I
+ :40C
0 :2oc '
": 5C
l I 1 4 I I I l I
0 10 20 30 40 50 50 70 80 90 100
Relative Humidity (7;)

39
corrugated board manufacturers is the fact that, during storage, a 100 %

recycled corrugated board may be exposed to long periods at a temperature
lower or higher than the temperature at which it was manufactured. Thus, if
the EMC remains the same, the 100% recycled corrugated board will
increase to a higher RH (or Aw) or decrease to a lower RH (or Aw) (figures
1 to 3). Consequently, in an atmosphere of constant relative humidity the
100 % recycled corrugated boards will absorb higher moisture level at lower
temperatures than at higher temperatures.

In order to describe the sorption isotherm by using a mathematical
expression, the Oswin equation (equation (9)) can properly be chosen and
applied. But the Oswin equation should be converted to the equation (19)
below:

LnM=K1+K2an(Aw/1-Aw) (19)

where M : equilibrium moisture content (EMC)

K1, K2 : constant

Aw : water activity
Tables 5 to 7 and figures 4 to 6 show the linear relationships between Ln
EMC and Ln (Aw / l-Aw). The linear regression was applied to the data in
figures 4 to 6 and the results are given in Table 8. All of the correlation
coefficients (r) were very close to l, which means the linear correlation was
good.

Any change in either RH (or Aw) or temperature can lead to a change in

the EMC and thus may affect the strength performances (such as edge crush
strength, flat crush resistance, and bursting strength) of boards. Therefore, it

is imperative to do moisture sorption isotherms for 100 % recycled

Table 5. Ln EMC vs. Ln (Aw/ l-Aw) for Board 1

 

Temperature = 40 °C :

EMC 3.44
Ln EMC 1.235
Aw 0.116

Ln (Awl l-Aw) -2 .03 1

Temperature = 20 °C :

EMC 4.72
Ln EMC 1.552
Aw 0.124
Ln (Awl I-Aw) -1.955
Temperature = 5 °C :
EMC 6.72
Ln EMC 1.905
Aw 0.14

Ln(Aw/I-Aw) -1.815

5.36

1.679

0.321
-0.749

7.12

1.963

0.336
-0.681

9.11
2.209
0.346
-0.637

6.80
1.917
0.492
-0.032

8.65

2.158 '

0.549
0.197

10.65
2.366
0.592
0.372

9.70

2.272
0.754
1.120

11.96
2.482
0.755
1.125

14.23
2.655
0.751
1.104

14.17
2.651
0.879
1.983

19.64
2.978
0.932
2.168

23.79
3.169
0.966
3.347

 

Table 6. Ln EMC vs. Ln (Aw / l-Aw) for Board 2

 

Temperature =

EMC
Ln EMC

Aw
Ln (Aw I I-Aw)

Temperature =

EMC
Ln EMC
Aw

Ln (Aw I l-Aw)

Temperature =

EMC
Ln EMC
Aw

Ln (Awl I-Aw)

40 °C :
3.60
1.281
0.116

-2.031

20 °C :
4.98
1.605
0.124

-1.955

5 °C:
7.53
2.019
0.14
-1.815

5.52

1.708

0.321
-0.749

7.28
1.985
0.336
-0.681

9.15

2.214
0.346
-0.637

7.05

1.953

0.492
-0.032

9.13

2.212
0.549
0.197

11.31
2.426
0.592
0.372

9.78

2.280
0.754
1.120

11.57
2.448
0.755
1.125

14.31
2.661
0.751
1.104

13.65
2.614
0.879
1.983

19.22
2.956
0.932
2.168

23.84

‘ 3.171

0.966
3.347

 

Table 7. Ln EMC vs. Ln (Aw/ l-Aw) for Board 3

 

Temperature = 40 °C :

EMC 3.18
Ln EMC 1.157
Aw 0.116

Ln (Aw/ I-Aw) -2.031

Temperature = 20 °C :

EMC 4.86
Ln EMC 1.581
Aw 0.124
Ln (Awl l-Aw) -1.955
Temperature = 5 °C :
EMC 7.61
Ln EMC 2.029
Aw 0.14

Ln(Aw/l-Aw) -1.815

5.14

1.637

0.321
-O.749

7.16

1.969

0.336
-0.681

9.26

2.226

0.346
-O.637

6.89

1.930

0.492
-0.032

9.13

2.212
0.549
0.197

11.75
2.464
0.592
0.372

9.96

2.299
0.754
1.120

11.50
2.442
0.755
1.125

14.70
2.688
0.751
1.104

13.69
2.617
0.879
1.983

19.34
2.962
0.932
2.168

23.83
3.171
0.966
3.347

 

Ln EMC

Ln EMC versus Ln (Aw l l -Avr)for Board 1

43

 

3.5 -

2.5

 

0.5

+

:4UC
0:2th

I

I

I

I

_

 

0

Ln (AW 11 -Avr)

Figure 4

1

 

Ln EMC

44

Ln EMC versus Ln (Aw ll -Aw)for Board 2

 

3.5

 

I I I I

 

I 1 l

 

-l 0 l 2
Ln (Aw ll Jaw)

Figure 5

 

Ln EMC

45
Ln EMC versus Ln (Aw i l -Aw)for Board 3

 

 

 

 

3.5 I l T I l f
.-/'
3 _ +140C
0 :20C ‘ 0,
": BC
2.5 - . o
‘0
2 " r
O
1.5 -
1 ..
0.5 l 1 1 1 I l
-3 -2 -l 0 l 2 3

Ln (Aw ll -Aw)

Figure 6

46

Table 8. Linear Regression for Ln EMC vs. Ln (Aw/ l-Aw)

 

Board 1 :
Temperature
40 °C
20 °C
5 °C

Board 2 :
Temperature
40 °C
20 °C
5 °C

Board 3 :
Temperature
40 °C
20 °C
5 °C

Linear Regression
Ln EMC = 1.931 + 0.3456 x Ln (Aw/ l-Aw)
Ln EMC = 2.146 + 0.3089 x Ln (Aw / l-Aw)
Ln EMC = 2.344 + 0.2457 x Ln (Aw/ l-Aw)

Linear Regression
Ln EMC = 1.948 + 0.3268 x Ln (Aw / l-Aw)
Ln EMC = 2.187 + 0.3149 x Ln (Aw / l-Aw)
Ln EMC = 2.390 + 0.2283 x Ln (Aw/ l-Aw)

Linear Regression
Ln EMC = 1.907 + 0.3617 x Ln (Aw/ l-Aw)
Ln EMC = 2.156 + 0.2969 x Ln (Aw/ l-Aw)
Ln EMC = 2.408 + 0.2268 x Ln (Aw/ l-Aw)

0.9985
0.9919
0.9970

0.9992
0.9908
0.9963

0.9994
0.9911
0.9755

 

r = correlation coefficient

47
corrugated boards at a minimum of two different temperatures to determine

the magnitude of the change of the strength performances of 100 % recycled

corrugated boards.

Edge Crush Strength (Under Saturated Salt Solutions’ Conditions) Versus
Equilibrium Moisture Content:

Appendix B and figures 7 to 9 show the relationships between edge
crush strength and relative humidity at the three different temperatures for
the three boards. In general, as relative humidity increased at any
temperature, edge crush strength decreased. As the temperature change fi'om
high to low under a fixed relative humidity, edge crush strength also
decreased. The reason for this is that the condition at higher relative
humidity and lower temperature tended to increase the solubility of water in
the board. The more moisture in the board, the lower the edge crush strength
of the board.

Because the relationship between the equilibrium moisture content
(EMC) and the relative humidity (RH) has been constructed by moisture
sorption isotherm, the relationship between the edge crush strength and the
EMC can be found by substituting EMC for RH. Tables 9 to 11 and figures
10 to 12 present the relationships between the edge crush strength and the
EMC at three different temperatures for three boards. According to figures
10 to 12, the curves show that the more the EMC, the less the edge crush
strength. Table 12 gives the results of the linear regression between edge
crush strength and EMC. All of the correlation coefficients were close to 1,

which means that linear correlation was good.

48
Edge Crush Strength of Board 1

35 r r r r r r r r

 

M IN.) Ln)
0 Ln 0

Edge Crush Strength {lbsfim}

Ln

 

 

 

I l l l l
10 20 30 40 . 50 60 1’0 80 90 100
Relative Humidity (it)

 

10 I l I

Figure 7

49
Edge Crush Strength of Board 2

 

4D I I I I I I I r

(a) (a)
D 01

M
01

Edge Crush Strength {Ibsfini}

20

 

I l l

 

 

 

15 l 1 I

L I
10 20 30 40 50 BE] 70 80 90
Relative Humidity (it)

Figure 8

100

Edge Crush Strength {Ibsfini}

50
Edge Crush Strength of Board 3

45 I I I I I I I I

 

40

LA.)
01

(a)
O

M
01

20

 

 

 

 

15 I I I I I I I I
10 20 30 40 50 50 i0 80 90 100
Relative Humidity (1.)

Figure 9

51

Table 9. Edge Crush Strength vs. EMC and RH for Board 1

 

Temperature = 5 °C :
Strength 25.64 23.24
(lbs/in.)
EMC 6.72 9.1 1
RH (%) 14.0 34.6

Temperature = 20 °C :
Strength 30.70 27.42
(lbs/in.)

EMC 4.72 7 .12
RH (%) 12.4 33.6

Temperature = 40 °C :
Strength 33.92 30.36
(lbs/in.)

EMC 3.44 5.36
RH (%) 11.6 32.1

22.56

10.65

59.2

25.28

8.65

54.9

28.40

6.80
49.2

19.36

14.23

75.1

22.68

11.96

75.5

25.09

9.70
75.4

13.56

23.79

96.6

17.82

19.64

93.2

22.25

14.17
87.9

 

52

Table 10. Edge Crush Strength vs. EMC and RH for Board 2

 

Temperature = 5 °C :
Strength 30.56 28.26 26.10 23.02 16.81
(lbs/in.)
EMC 7.53 9.15 11.31 14.31 23.84
RH (%) 14.0 34.6 59.2 75.1 96.6

Temperature = 20 °C :
Strength 36.67 33.76 30.64 27.95 20.60

(lbs/in.)
EMC 4.98 7.28 9.13 11.57 19.22
RH (%) 12.4 33.6 54.9 75.5 93.2

Temperature = 40 °C :
Strength 39.20 36.45 34.37 30.27 25.34
(lbs/in.)
EMC 3.60 5.52 7 .05 9.78 13.65
RH (%) 11.6 32.1 49.2 75.4 87.9

 

53

Table 11. Edge Crush Strength vs. EMC and RH for Board 3

 

Temperature = 5 °C :
Strength 31.81 29.29 26.23 23.13 16.93
(lbs/in.)
EMC 7.61 9.26 11.75 14.70 23.83
RH (%) 14.0 34.6 59.2 75.1 96.6

Temperature = 20 °C :
Strength 37.96 34.95 31.27 26.91 20.18
(lbs/in.)
EMC 4.86 7.16 9.13 11.50 19.34
RH (%) 12.4 33.6 54.9 75.5 93.2

Temperature = 40 °C :
Strength 40.22 38.62 36.20 31.44 25.52
(lbs/in.)
EMC 3.18 5.14 6.89 9.96 13.69
RH (%) 11.6 32.1 49.2 75.4 87.9

 

54
Edge Crush Strength of Board 1

 

 

 

 

EMC (g wateril 00 g dry weight)

Figure 10

35 r r r r
30- -
0
:9
£25— -
(I
E
2
£6
5
0
220- -
o
g +:5C
.3 0:2th
”:40C
15- -
10 I I l I
U 5 10 15 20 25

40

(A)
Ln

M (.50
01 D
I

Edge Crush Strength {Ibs.tin.}

M
O

I

55

Edge Crush Strength of Board 2

 

 

15
0

I I

 

I I

 

 

10 15
EMC (g wateril 00 g dry weight)

Figure 11

25

45

40

(A)
01

M
(n

Edge Crush Strength {Ibsfim}
00
O

+:5C
o:20C
20_ :40C , _
15 L l I l
0 5 10 15 20

56
Edge Crush Strength of Board 3

 

I

 

’I

I I I

'i

 

 

EMC (g wateril 00 g dry weight)

Figure 12

25

Table 12. Linear Regression for Edge Crush Strength vs. EMC

57

 

Board 1 :
Temperature

40 0C

20 °C

5 °C

Board 2 :
Temperature

40 °C

20 °C

5 °C

Board 3 :
Temperature

40 °C

20 °C

5 °C

Linear Regression
ECT = 36.35 - 1.0570 x EMC
ECT = 33.40 - 0.8271 x EMC
ECT = 29.85 - 0.6960 x EMC

Linear Regression
ECT = 44.11 - 1.3860 x EMC
ECT = 41.59 - 1.1180 x EMC
ECT = 35.76 - 0.8174 x EMC

Linear Regression
ECT = 45.55 - 1.4350 x EMC
ECT = 43.09 - 1.2340 x EMC
ECT = 37.44 - 0.8904 x EMC

0.9759
0.9813
0.9958

0.9995
0.9940
0.9891

0.9956
0.9834
0.9854

 

r = correlation coefficient
ECT = edge crush strength
EMC = equilibrium moisture content

58

Flat Crush Resistance (Under Saturated Salt Solutions’ Conditions) Versus
Equilibrium Moisture Content:

Appendix C and figures 13 to 15 show the relationships between the flat
crush resistance and the relative humidity at the three different temperatures
for three boards. In general, as the relative humidity increased, the flat crush
resistance decreased. As the temperature shifted from high to low under a
fixed relative humidity, the flat crush resistance also decreased. The reason
for this is the same as for that of edge crush strength. By substituting EMC
for RH from the sorption isotherm, tables 13 to 15 and figures 16 to 18
present the relationships between flat crush resistance and EMC at three
different temperatures for three boards. Table 16 shows the results of the
linear regression between flat crush resistance and EMC. All of the
correlation coefficients were close to l, which means that linear correlation

was good.

Strength Performances Under Recommended ASTM Conditions:

Table 17 shows the edge crush strength (Appendix B), flat crush
resistance (Appendix C), and bursting strength (Appendix D) for three
different boards under three recommended ASTM conditions. Figures 19 to
21 also present graphically the relationships between strength properties and
temperature. In general, under a fixed relative humidity (85%), any board
conditioned at lower temperature has lower strength performances. This
result is consistent with that found under saturated salt solutions’ conditions

(figures 7 to 9 and figures 13 to 15). The values of strength found under

59
recommended ASTM conditions are also consistent with those found under

saturated salt solutions’ conditions. Because, under the same temperature
condition, the values of strength (edge crush and flat crush) conditioned at
relative humidity 85 % are always in between those (higher values of
strength) conditioned at less than 85 % relative humidity and those (lower
values of strength) conditioned at greater than 85 % relative humidity. The
reason is that because less moisture is absorbed by the board when exposed
to lower than 85 % relative humidity, the board is stronger; and because
more moisture is absorbed by the board when exposed to greater than 85 %
relative humidity, the board is weaker.

The bursting strength of test samples could be tested only under the
recommended ASTM conditions, because the test samples were too big to
fit into the buckets used for creating the saturated salt solutions’ conditions.
Under a constant relative humidity (85%), the lower the temperature, the
lower the bursting strength. The reason is that the more moisture absorbed

by the board under the lower temperature, the lower bursting strength of the
board.

Linear Regression Equations To Re-build The Data:

Use linear regression equations from table 8, table 12, and table 16 to re-
build the data of RH, Aw, EMC, ECT, and FCR. The results are presented
in Appendix E. For each type of board under any condition, An increase in
RH (or Aw) by 10% (or 0.1 unit) decreases less ECT and FCR in the 10-
70% RH (or 0.1-0.7 Aw) range than the 70-90% RH (or 07-09 Aw) range.
The reason can be found from the EMC column, which shows that the three

60
types of boards absorbed less moisture in the 10-70% RH range than the 70-

90% RH range. Moreover, under the same RH, a change in temperature
from high to low decreased ECT and FCR, because of increased moisture
content. Therefore, moisture content is the main cause of reduced strength

performances.

40

Flat Crush Resistance of Board 1

61

 

—‘ h.) hr.) 00 LA)
01 D 01 O (11

Flat Crush Resistance {Ibsjsquare in.}

O

 

r

l

l

 

 

 

5
10

20

30

40

l I
50 60
Relative Humidity (7.)

Figure 13

70

80

90

100

Flat Crush Resistance of Board 2

62

 

4U

— h.) M L!) (a)
01 0 U1 0 01
I

Flat Crush Resistance {lstsquare in.)

O

 

1

I I

 

 

 

5
10

40

1 1
50 60
Relative Humidity (it)

Figure 14

70

80

90

100

40

Flat Crush Resistance of Board 3

63

 

-‘ M N (a) (I)
01 O 01 0 (J1
I

Flat Crush Resistance {lstsquare in.)

O

 

I

f

l

I T

 

 

 

5
10

20

30

40

1 I
50 50
Relative Humidity (‘1)

Figure 15

80

90

100

64

Table 13 Flat Crush Resistance vs. EMC and RH for Board 1

 

Temperature = 5 °C :
Strength 27.37 20.38 17.81 16.37 8.69

(lbs./in2.)
EMC 6.72 9.11 10.65 14.23 23.79
RH (%) 14.0 34.6 59.2 75.1 96.6

Temperature = 20 °C :
Strength 35.21 28.33 23.31 20.77 13.35
(lbs/inz.) ’
EMC 4.72 7 .12 8.65 11.96 19.64
RH (%) 12.4 33.6 54.9 . 75.5 93.2

Temperature = 40 °C :
Strength 37.32 34.13 30.97 23.45 18.81
(lbs/i112.)
EMC 3.44 5.36 6.80 9.70 14.17
RH (%) 11.6 32.1 49.2 75.4 87 .9

 

65

Table 14. Flat Crush Resistance vs. EMC and RH for Board 2

 

Temperature = 5 °C :

Strength 26.87
(lbs/inz.)
EMC 7.53
RH (%) 14.0
Temperature = 20 °C :
Strength 33.69
(lbs./in2.)
EMC 4.98
RH (%) 12.4

Temperature = 40 °C :

Strength 37.84
(lbs/inz.)
EMC 3.60

RH(%) 11.6

22.51

9.15

34.6

27.87

7.28

33.6

33.28

5.52
32.1

18.75

11.31

59.2

24.98

9.13

54.9

29.07

7.05
49.2

15.91

14.31

75.1

20.78

11.57

75.5

25.30

9.78
75.4

7.59

23.84

96.6

11.10

19.22

93.2

17.49

13.65
87.9

 

66

Table 15. Flat Crush Resistance vs. EMC and RH for Board 3

 

Temperature = 5 °C :

(lbs./in2.)

Temperature = 20 °C :

(lbs/in?)

Temperature = 40 °C :

abs/in?)

20.56

9.26

34.6

27.43

7.16

33.6

31.29

5.14
32.1

16.39

11.75

59.2

22.33

9.13

54.9

27.74

6.89
49.2

15.54
14.70
75.1

20.82
11.50
75.5

23.25

9.96
75.4

7.17
23.83
96.6
10.35
19.34
93.2
16.96

13.69
87.9

 

40

35

Flat Crush Resistance (lstsquare in.)

67

Flat Crush Resistance of Board 1

 

I

 

”I401:

I I

 

 

 

l
10 15
EMC (g wateril 00 g dry weight)

Figure 16

25

40

—‘ M M 00 (:0
(J1 0 Ln 0 (’1

Flat Crush Resistance {Ist‘squa’re in.)

O

68

Flat Crush Resistance of Board 2

 

 

 

 

 

EMC (g wateril 00 g dry weight)

Figure 17

l I T I
0\
- +:5C -
0:2UC
”:4th "\s
I l l l
D 5 10 15 20 25

40

—‘ M N.) La.) La.)
(J1 O 01 C) Ln

Flat Crush Resistance (lbsjsquare in.)

—.
O

69

Flat Crush Resistance of Board 3

 

 

 

 

EMC (g wateril 00 g dry weight)

Figure 18

I I I I
b
I:
- +:5C _
o:2UC
*24UC
— a —r
l l L I
0 5 10 15 20 25

Table 16. Linear Regression for Flat Crush Resistance vs. EMC

70

 

Board 1 :
Temperature

40 °C

20 °C

5 °C

Board 2 :
Temperature

40 °C

20 °C

5 °C

Board 3 :
Temperature

40 °C

20 °C

5 °C

Linear Regression
FCR = 43.14 - 1.8000 x EMC
FCR = 38.21 - 1.3450 x EMC
FCR = 30.45 ~ 0.9555 x EMC

Linear Regression
F CR = 44.23 - 1.9740 x EMC
FCR = 39.64 - 1.5290 x EMC
FCR = 32.87 - 1.0990 x EMC

Linear Regression
FCR = 41.15 -1.8000 x EMC
FCR = 38.47 - 1.5020 x EMC
FCR = 30.65 - 1.0160 x EMC

0.9851
0.9499
0.9429

0.9953
0.9899
0.9749

0.9936
0.9799
0.9654

 

r = correlation coefficient
FCR = flat crush resistance
EMC = equilibrium moisture content

Table 17. Strength under Recommended ASTM Conditions

 

Board 1 :
Temperature (°C)
RH (%)
Edge Crush
(lbs/in.)
Flat Crush
(lbs/in?)
Bursting
(lbs/inz.)

Board 2 :
Temperature (°C)
RH (%)
Edge Crush
(lbs/in.)
Flat Crush
(lbs./in2.)
Bursting
(lbs/in?)

Board 3 :
Temperature (°C)
RH (%)
Edge Crush
(lbs/in.)
Flat Crush
(lbs/in?)
Bursting
(lbs./in2.)

5
85.0
18.63
12.64

94

85.0
21.32

11.42

178

85.0
22.31

10.97

216

20
85.0
20.74
17.22

116

20
85.0
24.29
16.47

241

20
85.0
25.44
15.33

256

40
85.0
22.15
18.65

119

40
85.0
25.49
17.15

250

40
85.0
26.26
16.30

259

 

72

Edge Crush Strength at Relative Humidity = 85?.

 

27 T I I I F

M h.) M M M
M (A) 435 01 C!)

M

Edge Crush Strength {IbSJ‘I’Ix}

+:Board1

 

    

 

 

20 o : Board 2 _
" : Board 3
19 _
‘8 1 l l L l l
5 10 15 20 25 30 35 40

Temperature (C)

Figure 19

19

0') N CD
I

01

#
A

Flat Crush Resistance {Istsquare in.)

(A)
l

73
Flat Crush Resistance at Relative Humidity = 85?.

 

I

 

 

 

+:Boad1
ozBoad2
”:BomdS

 

 

10

l l
15' 20 25 30 35
Temperature (C)

Figure 20

40

74

Bursting Strength at Relative Humidity = 85%
250 I I ,1, I ' l I 4X

 

240 -

     
 

+:Board1
ozBoard2 _
“:Board3

d

h

C)
I
I

Bursting Strength (lbs .tsquare‘ in .}

120- _

1130/ ..

80 l l l I
5 10 15 2D 25 30 35 40
Temperature (C)

 

 

 

Figure 21

CONCLUSIONS AND FUTURE RESEARCH

The conclusions of this study were:

1. The moisture sorption isotherm of 100% recycled corrugated board
shows that for a given equilibrium moisture content an increase in
temperature results in an increase in relative humidity (or water activity).
The Oswin equation can be properly applied to describe this moisture

sorption isotherm.

2. Edge crush strength and flat crush resistance are strongly affected by any
change in either relative humidity or temperature. In general, a condition of
higher relative humidity and lower temperature tends to increase the
solubility of the board. The more water in the board, the lower the strength
performances of the board. The high correlation coefficients (close to 1)
indicate that these results are quite reliable. Bursting strength is also
strongly affected by change in temperature under a constant 85% relative
humidity. The lower the temperature, the lower the bursting strength. The
reason is that the lower temperature causes the board to absorb more

moisture thereby reducing its bursting strength.
3. The values of both edge crush and flat crush under the recommended

ASTM conditions are consistent with those under the saturated salt

solutions’ conditions.

75

76
A more detailed study needs to be carried out to construct the moisture

desorption isotherm, test the bursting strength under saturated salt solutions’
conditions, and evaluate other physical properties under saturated salt
solutions’ conditions and recommended ASTM conditions. In this way, the
effect of moisture on 100 % recycled corrugated board can be conclusively

studied.

APPENDICES

77
Appendix A : Equilibrium Moisture Content

Tebier1.EquIlibriumMoistueContentotBoerd1eth40'C.Ri-i=11.6%.
W1 :equllibriumweight betoreoven dry

W22dryweight

EMC2gweter/100gdryweight

 

Sample W1 (g) W2 (9) EMC (%)
2.8513 2.7632 3.19
2.7874 2.6972 3.34
2.8965 2.801 3.41
2.8006 2.714 3.19
2.88 2.7807 3.57
. 2.7276 3.48
2.8027 2.7015 3.75
2.8676 2.7702 3.52
2. 8462 2.7529 3.39
2 7754 2.6811 3.52
Megn 3. 44
Std. Dev. 0.17

3004mmauna
to
&

Table A-2. Equilibrium Moisture Content of Board 1 at T = 40 °C. RH = 32.1%.
W1 : equilibrium weight before oven dry

W2 : dry weight

EMC : g water/100 g dry weight

 

 

Sample wr ) we (9) sure 1%)
2.81132 2. 6767 5. 29
2.9262 2.7755 5.43
2.9257 2.7769 5.36
2.9221 2.7673 5.59
2.9487 2.8036 5.18
2.9614 2.8049 5.58
2.8811 2.7305 5.52
2. 7849 2.641 5.45
2. 9505 2.8062 5.14
2 9091 2.7679 5.10
Men 5.36
Std. Dev. 0.18

 

ammummbund

Table A-3. Equilibrium Moisture Content oi Board 1 at T s 40 'C. RH = 49.2%.
W1 : equilibrium weight before oven dry

W2 : dry weight

EMC : g water/100 g dry weight

 

 

Sample W1 (9) W2 (g) EMC (it)
2. 9354 2. 7433 7.00

2.96 2.7669 6.98
2.9197 2.7307 6.92
2.8153 2.6412 6.59
2.7854 2.6053 6.91
. 2.7704 6.70
2.9446 2.7564 6.84
2.9218 2.7361 6.79
2.9773 2.7945 6.54
2.9686 2.7821 6.70
Mean 6.80
Std. Dev. 0.16

SOONOUI&UN-fi
re
3
m

 

78

Table A-4. Equilibrium Moisture Content of Board 1 at T a 40 ’0, RH = 75.4%.
W1 : equilibrium weight before oven dry

W2 : dry weight

EMC : g water/100 g dry weight

Sample W1 (9L W2“! EMC (*L
1 3.0414 2.7829 9.29
2.9587 2.6987 9.63
2.9996 2.7379 9.56
2.9971 2.7271 9.90
2.3935 2.5371 9.73

 

accummbun
.....“

N

0

Table A-5. Equilibrium Moisture Content of Board 1 at T = 40 °C. RH = 87.9%.
W1 : equilibrium weight before oven dry

W2 : dry weight

EMC : g water/100 g dry weight

Sample W1 (9) W239) EMC (31)

3.1334 2.7365 14.50
3.243 2.8337 14.44
3.2562 2.8519 14.25
3.1972 2.7952 14.38
2.995 2.6259 14.06
. 2.6732 13.89
3.06 2.6813 14.12
3.096 2.7184 13.89
3.1859 2.7948 13.99

3.1553 2.764 14.15—
Mean 14.17
Std. Dev. 0.22

 

SOONOUIAQN-h
0.1

Table A-6. Equilibrium Moisture Content of Board 2 at T = 40 °C. RH = 11.6%.
W1 : equilibrium weight before oven dry

W2 : dry weight

EMC : g water/100 g dry weight

Sample W1 19) ME) we (11)

3.7702 3.3437 3.47
3.3237 3.3925 3.55
3.3134 3.4377 3.30
3.5471 3.4319 3.33
3.53 3.4533 3.50

. . 3.51
3.3235 3.4393 3.34
3.3902 3.553 3.33
3.7239 3.5337 3.93
3.731 3.3115 3.31
Meg 3.30

513. Dev. 0.22

 

 

300NGG¥UN~3
u
h.
u

 

79

TablaA-7. EqdlbrkrmMolshnCorMofBoardZdT-fl'c. RH=32.1%..
W1 :eqmweiglibefmwandry

W2zdryweigfl

EMC:gwater/100gdryweight

 

 

 

aoowomguna
0 I I“ I O U I

go

a

3

N

d

a

TaleA-O.EqLIIernMoishaaCaMddeZdT-40'C.RH-75.4%.
W1zequiiibriummightbeforeovendy

W2zdyweigid

EMC:gwder/1wgd'ywelght

Sample W1 (9) W2 (91 EMC (at)
1 ems 3.5333 9.49

 

2 3%31 3.3033 9 82
3 3.8323 3.493 9 72
4 4.0348 3.8714 9 90
5 3.91 $ 3.57 9 72
8 3.“ 3.8053 9 84
7 3.91 83 3.5782 9 50
8 3.8717 3.5213 9 95
9 3.8799 3.5274 9.99
10 3.901 3.54% 9.89

 

Mean 9.78
Std. Dev. 0.17

80

Table A-10. Equilibrium Moisture Content 01 Board 2 at T c 40 °C, RH = 87.9%.
W1 : equilibrium weight before oven dry

W2 : dry weight

EMC : g water/100 g dry weight

 

Sample W1 (2) W2 m we (11)
4.0292 3.5567 13.28
3.8784 3.4133 13.63
4.0594 3.568 13.77
4.0989 3.5967 13.82
4.0206 3.5303 13.89
4.1043 3.8159 13.51
4.1736 3.8789 13.45
4.0485 3.5617 13.67
4.1126 3.6196 13.62
4.1522 3.6454 13.90
Meg 13.65
Std. Dev. 0.20

 

SDONOMbQN-e

Table A-11. Equilibrium Moisture Content of Board 3 at T = 40 '0. RH = 11.6%.
W1 : equilibrium weight before oven dry

W2 : dry weight

EMC : g water/100 g dry weight

 

Sample W1 m W2 (g) EMC (11)
4.6857 4.5491 3.00
4.6134 4.4824 2.92
4&1 4.5514 3.22
4.6024 4.4551 3.31
4.6361 4.4872 3.32
4.6977 4.5481 2.57
4.7173 4.5699 3.23
4.7391 4.5837 3.39
4.689 4.5343 3.41
4.5568 4.4067 3.40
Mearn 3.18
Std. Dev. 0.27

 

ammwooaiauN-e

Table A-12. Equilibrium Moisture Content of Board 3 at T . 40 '0. RH = 32.1%.
W1 : equilibrium weight before oven dry

W2 : dryweight

EMC : g water/100 g dry weight

Sample W139) mm 51110 El

4.705 4.4797 5.03
4.686 4.4818 5.02
4.6961 4.4659 5.15
4.7812 4.5432 5.24
4.71 16 4.4806 5.16
4.8923 4.6532 5.14
4.6771 4.4457 5.21
4.7172 4.4805 5.28
4.776 4.5465 5.05
4.7388 4.5068 5.15
Meg 5.14

Std. Dev. 0.09

 

 

soowmmauna

81

Table A-13. Equilibrium Moisture Content of Board 3 at T = 40 '0, RH = 49.2%.
W1 : equilibrium weight before oven dry

W2 : dry weight

EMC : g water/100 g dry weight

 

Sample W1 (11 mm EMC (it)

 

 

1 4. 8697 4. 5575 6. 85
2 4.8695 4.5559 6.88
3 4.7225 4.4162 6.94
4 4.7735 4.4875 6.85
5 4.7897 4.4888 6.70
6 4.8909 4.5748 6.91
7 4.843 4.5302 6.90
8 4.7431 4.4338 6.98
9 4.7555 4.4503 6.86
10 4.7938 4.4807 6.99

May 6.89

 

Std. Dev. 0.08

Table A-14. Equilibrium Moisture Content of Board 3 at T = 40 'C. RH = 75.4%.
W1 : equilibrium weight before oven dry

W2 : dry weight

EMC : g water/100 g dry weight

 

 

 

Sample W1 (1) W2 (9) EMC (11)
1 5.0249 4.5713 9. 92
2 4.9092 4.4654 9.94
3 4.9674 4.5137 10.05
4 4.8743 4.4347 9.91
5 4.878 4.4433 9.78
6 5.0167 4.5843 9.91
7 4.8695 4.4288 10.00
8 5m 4.5647 9.97
9 5.0324 4.5746 10.01
10 5.0317 4.5718 10.06

Mean 9.96

 

513.5”. 0.03

Table A-15. Equilibrium Moisture Content of Board 3 at T = 40 ‘0, RH = 87.9%.
W1 : equilibrium weight before oven dry

W2:dryweight
EMC : g water/100 g dry weight

Sample W1 (9) mm 3143 (%)

 

 

 

1 5.4163 4.745 14.15
2 5.4414 4.767 14.15
3 5.2383 4.5967 13.96
4 5.125 4.5094 13.80
5 5.0773 4.4748 13.46
6 5.302 4.6618 13.74
7 5.1704 4.552 13.58
8 5.0342 4.4391 13.41
9 4.976 4.3815 13.57
10 5.0516 4.4577 13.32
Meg 13.69

Std. Dev. 0.30

 

Table A-16. Equilibrium Moisture Content of Board 1 at T = 20 'C. RH = 12.4%.

82

W1 : equilibrium weight before oven dry
W2 : dry weight
EMC : g water/100 g dryweight

 

 

 

 

Sample W1 g9) W2 (g) EMC (fl
1 2.5447 2.4366 4.44
2 2.6234 2.5089 4.65
3 2.4781 2.3607 4.89
4 2.6088 2.4917 4.70
5 2.5912 2.4717 4.83
6 2.5907 2.4713 4.83
7 2.6075 2.4912 4.67
8 2.6075 2.4845 4.95
9 2.8164 2.505 4.45
10 2.5929 2.4744 4.79

Mean 4.72
Std. Dev. 0.17

 

Table A-17. Equilibrium Moisture Content of Board 1 at T = 20 °C, RH = 33.6%.

W1 : equilibrium weight before oven dry
W2 : dry weight
EMC : g water/100 g dry weight

 

 

 

 

Sample W1 11) W2 Q EMC 5%)
1 2.6274 2.4557 6.99
2 2.6849 2.5114 6.91
3 2.5558 2.3836 7.2
4 2.7079 2.5265 7.18
5 2.7481 2.5667 7.07
6 2.7161 2.5343 7.17
7 2.6321 2.4539 7.28
8 2.6969 2.5155 7.21
9 2.575 2.4024 7.18
10 2.7945 2.6107 7.04

Mean 7.12
Std. Dev. 0.12

 

Table A-18. Equilibrium Moisture Content of Board 1 at T = 20 °C. RH = 54.9%.

W1 : equilibrium weight before oven dry
W2 : dry weight
EMC : g water/100 g dry weight

 

 

 

 

Sample W1 (g) W241) EMC (1‘)
1 2.9703 2.7513 7.96
2 2.8864 2.6642 8.34
3 2.8661 2.8427 8.45
4 2.7287 2.5071 8.76
5 2.7783 2.5551 8.74
6 2.9028 2.6698 8.73
7 2.9673 2.7275 8.79
8 2.8248 2.5949 8.86
9 2.9562 2.7158 8.85
10 2.7769 2.5479 8.99

Mean 8.65
Std. Dev. 0.31

 

83

Table A-19. Equilibrium Moisture Content of Board 1 at T = 20 ’C, RH = 75.5%.
W1 : equilibrium weight betore oven dry

W2 : dry weight

EMC : g water/100 g dry weight

 

 

 

Sample W1 fl W2 ( ) EMC (16)
1 2.806 2.5139 11.62
2 2.8576 2.5443 12.31
3 2.9054 2.5933 12.03
4 2.7516 2.4583 11.93
5 2.7856 2.4889 11.92
6 2.755 2.462 1 1 .90
7 2.7692 2.466 12.30
8 2.8484 2.5448 1 1 .93
9 2.7698 2.4744 11.94
10 2.6696 2.3888 11.75

Mn 11.96
Std. Dev. 0.21

 

 

Table A-20. Equilibrium Moisture Content of Board 1 at T = 20 '0, RH = 93.2%.
W1 : equilibrium weight before oven dry

W2 : dry weight

EMC : g water/100 g dry weight

 

 

 

 

Sample W1 (3‘) W2 (31 EMC (16)
1 2.9531 2.4732 19.40
2 3.0567 2.5565 19.57
3 3.0433 2.5417 19.73
4 3.0983 2.5947 19.41
5 2.8564 2.3825 19.89
6 2.9801 2.4784 19.44
7 3.062 2.5559 19.81
8 2.8799 2.4083 19.58
9 3.1355 2.6193 19.71
10 3.1371 2.6181 19.82

MeIarn 19.64
Std. Dev. 0.18

 

Table A-21. Equilibrium Moisture Content of Board 2 at T = 20 '0. RH = 12.4%.

W1 : equilibrium weight before oven dry

W2:dryweight
EMC : g water/100 g dry weight

 

 

 

 

Sample W1 (9‘) w: (3L EMC (16)
1 3.4784 3.3156 4.91
2 3.4754 3.3121 4%
3 3.4871 3.3245 4.89
4 3.4647 3.3066 4.78
5 3.4834 3.3167 5.03
6 3.5131 3.3439 5.06
7 3.4731 3.3046 5.10
8 3.4959 3.3256 5.12
9 3.4304 3.2667 5.01
10 3.4763 3.3103 5.01

Mean 4.98
Std. Dev. 0.10

 

Twle A-22. Equilin Moisture Content of Board 2 at T 8 20 °C. RH 8 33.6%.

84

W1 : equilibrium weight before oven dry
W2 : dryweight
EMC : g water/100 g dry weight

 

 

 

 

Sample W1 ill W2 «1) EMC (:1)
1 3.4945 3.2602 7.19
2 3.5182 3.2805 7.25
3 3.3936 3.161 7.36
4 3.4377 3.2049 7.26
5 3.5046 3.2639 7.37
6 3.4863 3.2508 7.24
7 3.4946 32582 7.26
8 3.4131 3.1798 7.34
9 3.4346 3.2011 7.29
10 3.5071 3.2696 7.26

Mean 7.28
Std. Dev. 0.06

 

Table A-23. Equilibrium Moisture Content of Board 2 at T = 20 ’C. RH = 54.9%.

W1 : equilibrium weight before oven dry

W2:dryweight
EMC : g water/100 g dry weight

 

 

 

 

Sample W1 (3) w: (9) EMC (11)
1 3.3555 3.3554 3.94
2 3.3374 3.3343 3.94
3 3.5515 3.2531 9.07
4 3.5453 3.2522 9.02
5 3.344 3.3434 3.33
3 3.5113 3.2155 9.21
7 3.5137 3.2143 9.30
3 3.3335 3.3224 9.33
9 3.3033 3.2993 9.30
10 3.5903 3.234 9.33

Men 9.13
Std. Dev. 0.19

 

Table A-24. Equilibrium Moisture Content of Board 2 at T a 20 '0. RH = 75.5%.

W1 : equilibrium weight before even dry

W2:dryweight
EMC : gwaterl100g dry weight

 

 

 

 

Sample W1 ill W2 51) EMC (1‘)
1 3.7036 3.3255 11.37
2 3.4872 3.1093 11.51
3 3.5865 3206 11.36
4 3.5086 3.1531 1 1 .27
5 3.5406 3.1709 11.66
6 3.6366 3.2572 11.65
7 3.5861 3.209 11.75
8 3.5478 3.1754 11.73
9 3.8662 3.2823 11.70
10 3.5614 3.1879 1 1 .72

Mean 11.57
Std. Dev. 0.18

 

Table A-25. Equilibrium Moistue Content of Board 2 at T 8 20 °C. RH = 93.2%.

85

W1 : equilibrium weight before oven dry
W2: dryweight
EMC : g water/100 g dry weight

 

Sample W1 1.9L W: (3L EMC Qt)—

 

 

 

1 3.7981 3.1819 19.37
2 4.0878 3.4253 19.34
3 3.8248 3.2049 19.34
4 3.8231 3.2042 19.32
5 3.9297 3.3042 18.93
6 3.9398 3.3114 18.98
7 3.9362 3.3002 19.27
8 3.862 3.2362 19.34
9 3.9415 3.3027 19.34
10 3.9019 3.2792 18.99
Mean 19.2

Std. Dev. 0.18

 

Table 11.23. Equilibrium Moisture Content or Board 3 31 T = 20 '0. RH . 12.4%.

W1 : equilibrium weight before oven dry
W2 : dry weight
EMC : g water/100 g dry weight

 

 

 

 

Sample wm W2 (g_) EMC (16)

1 4.4318 4.2394 4.54
2 4.3967 4.1902 4.93
3 4.3978 4.1875 5.02
4 4.2743 4.0732 4.94
5 4.3569 4.1534 4.90
6 4.2829 4.0737 5.14
7 4.2198 4.0204 4.96
8 4.3026 4.101 1 4.91
9 4.3202 4.129 4.63
10 4.3456 4.1536 4.62
Mean 4.86

Std. Dev. 0.19

 

Table A-27. Equilibrium Moisture Content of Board 3 at T = 20 °C. RH I 33.6%.

W1 : equilibrium weight before oven dry
W2 : dry weight
EMC : gwaterl100g dryweight

 

 

 

 

Sample W1 19L W2 l1) EMC El
1 4.212 3.9453 6.78
2 4.4552 4.1721 6.79
3 4.322 4.0403 7.15
4 4.3557 4.062 7.23
5 4.3231 4.0313 7.24
6 4.4251 4.1272 7.22
7 4.209 3.9979 7.33
8 4.3431 4.0461 7.34
9 4.2566 3.9664 7.32
10 4.4065 4.1089 7.24

Mean 7.16
Std. Dev. 0.21

 

Table A-28. Equilibrium Moisture Content of Board 3 at T = 20 °C, RH = 54.9%.

86

W1 : equilibrium weight before even dry
W2:dryweight
EMC : g water/100 g dry weight

 

 

 

 

Sample W1 fl W2 $1) EMC (16)
1 4.5953 4.202 9.18
2 4.5955 4.2073 9.23
3 4.5249 4.1433 9.21
4 4.4774 4.1009 9.18
5 4.4735 4.0998 9.12
6 4.5061 4.1276 9.17
7 4.8564 4.2657 9.16
8 4.4845 4.1099 9.11
9 4.636 4.2498 9.09
10 4.7821 4.213 8.90

fin 9.13
Std. Dev. 0.09

 

Table A-29. Equilibrium Moisture Content of Board 3 at T = 20 °C. RH = 75.5%.

W1 : equilibrium weight before oven dry

W2 : dry weight
EMC : g water/100 g dry weight

 

 

 

 

Sample W1 (g_) W2 19L EMC (it)
1 4.5927 4.1142 11.63
2 4.6795 4.1879 11.74
3 4.5943 4.1112 11.75
4 4.5224 4.0499 1 1.67
5 4.5185 4.0489 1 1 .60
6 4.8747 4.191 11.54
7 4.5854 4.1079 1 1 .62
8 4.8751 4.1956 11.43
9 4.517 4.0662 1 1 .09
10 4.6675 4.2057 10.98

Mean 1 1.50
Std. Dev. 0.27

 

Table A-30. Equilibrium Moisture Content of Board 3 at T = 20 'C, RH = 93.2%.

W1 : equilibrium weight before oven dry

W2:dryweight
EMC : gwaterl1mg dryweight

 

 

 

 

Sample W151) W2 l1) EMC (11)
1 5.0268 4.212 19.34
2 4.9562 4.147 19.51
3 4.9927 4.1818 19.39
4 4.9284 4.135 19.19
5 4.9641 4.1528 19.54
6 4.985 4.1766 19.36
7 4.9342 4.1319 19.42
8 4.9608 4.1515 19.49
9 4.9264 4.128 19.2
10 5.0189 4.238 18.82

Megn 19.34
Std. Dev. 0.21

 

87

TableA-31.Eq1mMolstinConteraofBoerd1aT-S’C.RH-14.0%.
W1:equllibriumwelglabeforeovenay

W2:dyweigrd

EMC:gweterI100gdryweight

Sample W1 (9) W2(g) EMC (11)
' 7.00

 

 

 

 

1 2.6085 24379

2 2.6361 24581 7.24
3 26387 2.4654 7 03
4 2559 2.257 6 82
5 27069 25433 6 43
6 2.7196 2.5574 8 34
7 27131 2.5508 6 36
8 27113 2.5492 8 38
9 2.8778 2.5006 7 09
10 2.7382 2.5714 6 49
Mean 6 72

Std. Dev. 0 35

 

TableA-32.EqulibrhmMoishrreContentofBoerd1aT-S’C.RH-34.6%.
W1:equilibriumwelghtbeforeovendry

W2:dryweight

EMC:gwater/100gayweight

 

Sample W_1_(g_) 1112(2) EMC (11)

 

 

 

1 2.7679 2.5544 8.36
2 2.7637 2.5432 8.87
3 2.7476 2.521 8.94
4 2.8333 2.5983 9 04
5 2.7188 24909 9 15
6 2.6202 2.287 9 33
7 2.6602 24331 9 33
8 2.8049 25665 9 29
9 2.7923 2.5527 9 2
10 2.7426 2.5029 9.58
Mean 9.1 1

Std. Dev. 0.37

 

 

TableA-33.Eq1mbriumM0lstureContemofBoerdi aT-S'C.RH859.2$.
W1zequillbriumwelghtbeforeovendry

W2:dryweight

EMC:gwater1100gdrymight

Sample W1 (1) W29) EMC (11)

 

 

1 29393 2.65“ 10.58

2 2.8488 2.579 10.46

3 2.858 2.5869 10.48

4 2.8143 2.54% 10.53

5 2.8349 2.3773 10.84

6 2.8199 2.5“7 10 80

7 2.5784 2.3343 10 46

8 26344 2.3785 10 76 .
9 2.621 2.3775 10 82

10 2.8356 2 55% 1

 

 

 

86

waA-34.EWWCMJM1ITO5'C.RHIT5.1$.

wumwmmm
W2:dywolgn

Maw/magnum:

Sample WM m (g) 5110 m

 

 

 

 

 

1 27299 2.3919 14.13
2 27759 2.4199 14.71
3 27099 24425 1422
4 20309 24773 1427
5 27503 24122 14.02
0 27034 23090 14.00
7 2.0079 24595 14.17
0 27709 2.4335 1424
9 20334 24013 14.19
10 2.9234 2.5573 14.32
Mega 14.23

510. Dev. 0.19

 

TabloA-35.EqwibrmM0ldur900tM0180td1dT-5’0.RH-98.8%.
W1:0quflibflunmlgl11woreamdry

W2:d'ywalgl'11

EMC:9wator/1009aywolglt

Sample W1 (92 W2 (2! EMC (112

3.0166 2. 4372
3.131 2.5434 2.:
2%76 2.4064 24.01
3.1432 2.543 23.80
3.0244 2.4466 23.62
2.6776 24022 23.5
3.0543 2.4716 23.57
3.01” 24345 24.04
3.1001 2.5016 23.62
2.64% 2.372 23.67

 

acouomawen-n

 

 

 

 

7.01.430.mmwamuT-s'cJH-Mm.
W1zoqulllmtlmwn0dmomay

W2zctyw0lgl1l

magma/10090719019111

Sample W1 (g) "21!! EMC 90m

3. 2447
3.4744 3.2415 7.18
3.4774 3.321 7.56
3.4462 3.200 7.52
3.5045 3.2564 7.52
3.4677 3.2503 7.61
3.4757 3.2271 7.70
3.5271 3.275 7.70
3.531 32002 7.70
3.4335 3.1816 7.61

 

soouaugun-o

TwltA-37.WWWNM2IT'5’C.RH-3&6fi.

W1 :oqulbdunmbdonovanw
W2:drywlgli
EMC:gWIt0r/1mgdrywolgfl

 

 

 

 

Sample W1 (g! W2 (g) EMC El
1 3.5509 3.2496 9.27
2 3.5125 32158 923
3 3.5706 32663 9.32
4 3.589 32848 926
5 3.5822 32777 9.29
6 3.5433 3243 9.28
7 361$ 3.3101 9.18
8 3.5137 3.2127 9.06
9 3.5571 31654 6.93
10 3.539 3.2559 8.69

M0311 9.15
Std. 00v. 0.20

 

TIblSA-36.EquflibdummmdMZdT85'C,RH-562%.

W1zoqwlbrlunwdgl1tbcfotl0mdly
W2:drywelght
EMC:gunt0r/1Mgdywdgfl

 

 

 

 

Sample W1 (1) W2 (9) EMC (11!
1 3.6009 3.2381 11.20
2 3.7002 3.3947 11.36
3 3.7868 3.41 11.05
4 3.7347 3.3567 1126
5 3.7801 3.396 11.31
6 3.6058 3.2373 11.38
7 3.6021 3.235 11.35
8 3.6002 3.2394. 11.14
9 3.4388 3.0933 11.17
10 3.7201 3.3243 1 1 .91

M090 1 1 .31
Std. 00v. 0.23

 

Tuhch-fl.EWWWdWZITls’Cfil-IITSJS.

W1zoquwmmmlglubofmovmdry

 

 

 

W2 : cry weigh
EMC : 9 “01/100 9 6y might
Sample W1 (1) W2 (9) EMC g)
1 3.6798 3.2082 14.70
2 3.7183 3.2573 14.15
3 3.6988 3.2313 14.47
4 3.7032 32987 14.13
5 3.6888 32332 14.09
8 3.7899 3.3187 14.20
7 3.6894 3.2194 14.60
8 3.7034 3.2464 14.08
9 3.6323 3.1757 14.38
10 3.6821 3.2200 14.3
Mean 14.31

 

0.23

TwltA-40.EWWWdMZdT-5'C.RH'”.6$.

90

W1zeqwibrl1mwelaflbelonovend'y

 

 

 

 

W2 : 19y weight
EMC : owner/1009 dywelght
Sample W1 (31 W2 19! EMC El
1 4.0419 32654 23.78
2 4.1156 3.3258 21.75
3 4.1138 3.3129 24.02
4 3.8932 3.1463 23.74
5 4.0268 32486 20.95
8 4.0207 32490 23.72
7 4.1137 3.3257 23%
8 4.1332 3.2929 24.00
9 4.1123 3.3294 23.51
10 3.9604 3.1885 24.21
M0311 23.84
Std. Dev. 0.20

 

Tehl0A-41.EqdllbtlunMolstur00011t0ntotBoerd3etT-5'C.1111-14011.

W1:equlllbrlummlgl1tbel'0r00vendty
W2:dryweight
EMC:gweter/1009dymlght

 

 

 

 

Sample W1 (g_) 1172(1) EMC (111

1 4.5813 4.2585 7.58
2 4.5925 4.2759 7.40
3 4.5425 4.2277 7.45
4 4.4726 4.1592 7.54
5 4.4741 4.1599 7.55
8 4.5215 4.1972 7.73
7 4.4236 4.0999 7.90
8 4.5768 4.2531 7.81
9 4.5129 4.1961 7.55
10 4.5012 4.1784 7.78
M0011 7.61

Std. Dev. 0.15

 

TebleA-42 EWMoletureCMotBoerd3dT-5'Cfil-1-346‘fi.
W1 :equllbdunwelgflbefonavendry

 

 

 

W2 . dry welght
EMC : g water/100 9 MW
891111110 W1 81) W2 (2! EMC E)
1 4.5318 4.1422 9.41
2 4.5733 4.1904 9.14
3 4.5468 4.1489 6.64 —
4 4.5628 4.1771 9.23
5 4.501 1 4.1 189 9.28
8 4.501 4.1 192 917
7 4.5989 4.21 24 9.18
6 4.4179 4.048 9.16
9 4.4774 4.1031 9.12
10 4.6818 4.2700 9.16
M0011 9.26

 

Std. 50v.

TableA-43.EMdeM3dT-5'Cfifl-592S.

Whammwmmdy
W2:dryw0lght
EMC:gwetor/1$gdyw0lgfl

 

Sample W1 m M35509, £11001!

 

 

 

1 4. 8718 11.90
2 4.7778 42937 1127
3 4.7321 42$3 12.15
4 4.6678 4.1889 11.97
5 4.41 $ 3.9408 11.96
8 4.4711 399$ 11.99
7 4. 7501 4.2414 11.$
8 4. $88 4.1965 11.97
9 4.5921 4.1311 11.18
10 4.7698 4.2876 11 .gg_
M0111 11.75
Std. Dev. 0.37

 

TableA-44.Equllibri.1111M01010100011te11101800163IT-5°C. Rl-l 375.1%,

W1zequllib1lu111welgl1tbeforemnd1y

 

 

 

 

W2 : dry welght
EMC :gweter/1$g¢ywelgl'lt
Sample W1 01) W2 (1L EMC (5L
1 4.7906 4.1872 14.41
2 4.7601 4.1409 14.5
3 4.7321 4.1332 14.49
4 475$ 4.1392 14.92
5 4.61$ 4.0159 14.97
6 4.6611 4.575 14.88
7 4.7501 4.1451 14.80
8 4.8288 4.2261 14.26
9 4.7121 4.1063 14.75
10 4.6812 4.0781 14.7_9__
Megn 14.70
Std. D0v. 0.25

 

nun-45.emmmmdmauT-5°C.RH-90.011

W1:eqwlb1111mweightbefaeovendly
W2:d1yvlelght
EMC:gweter/1009aywelght

 

Sample 1141(2) wag) EMC m

 

 

 

1 5.1401 4.1472
2 5.1329 4.1597 2. 40
3 5.0903 4.1139 24.04
4 5.0712 4.0951 $.84
5 5.0169 4.0549 $.72
6 5.170 4.1759 $.92
7 5.1201 4.1$5 $.$
8 5.1$8 4.1$8 $.89
9 5.1221 4.1334 $.92
10 5.0858 4.1031 $.95
M0311 23. 83
Std. D0v. 0.19

 

 

92

Appendix B : Edge Crush Strength

Table B-1. Edge Crush Strength of Board 1 at T = 5 °C, RH = 14.0%.
Sample Edge Crush Strength (lbe.lln.)

 

1 23.45
30.55
24.05
25.20
26.00
23.05
27.95
30.05
22.05
24.00
Mean 25.64

ammqombwn

 

Std. Dev. 2.96

Table 8-2. Edge Crush Strength of Board 1 at T = 5 °C, RH = 34.6%.
Sample Edge Crush Strength (lbeJln.)

 

 

 

1 23.95

2 26.95

3 27.35

4 22.95

5 18.50

6 23.55

7 21.05

8 25.05

9 20.05
10 22.95
Mean 23.24
Std. Dev. 2.83

 

Table 8-3. Edje Crush Strength of Board 1 at T = 5 °C. RH = 59.2%.
Sample Edge Crueh Strength (lstin.)

 

22.25
22.50
18.70
23.50

27.95
23.35
24.65
20.95
21.55
20.15

Mean 22.56
Std. Dev. 2.57

somumm 20010-1

93

Table B-4. Efidge Crush Strength of Board 1 at T = 5 “C. RH = 75.1%.
Sample Edge Crush Strength (lbe.lln.)

 

 

 

1 19.05

2 18.95

3 21.95

4 18.55

5 20.00

6 17.55

7 18.50

8 21.00

9 18.65
10 19.35
Mean 19.36
Std. Dev. 1.30

 

Table B-5. Edge Crush Strength of Board 1 at T = 5 °C, RH = 85.0%.

Sample Edge Crush Strenfih Slbe.lln.2

 

17.20
16.05
18.75
17.85
17.05
18.00
15.75
19.05

20.95

25.65
Mean 18.63

3‘0 ooxlmcnwa-t

 

Std. Dev. 2.89

Table B-6. Edge Crush Strerlgth of Board 1 at T = 5 ‘C. RH = 96.6%.
Sample Edge Crueh Strength (lbeJin.)

 

14.30
15.80
13.20
13.75

14.95
11.15
13.55
12.25
13.25
13.35
Mean 13.56
Std. Dev. 1.31

gomumm 200154

94

Table B-7. Edge Crush Strength of Board 2 at T = 5 °C, RH = 14.0%.
Sample Edge Crush Strength (Ibe.lln.)

 

 

 

1 30.40
2 26.25
3 33.95
4 25.10
5 31.35
6 32.45
7 30.75
8 34.45
9 29.65
10 31.25
Mean 30.56
Std. Dev. 2.99

 

Table 00. Edge Crush Strength of Board 2 at T = 5 'C. RH = 34.6%.
Sample Edge Crueh Strength (lbe.lln.)

 

1 24.20
25.95
30.35
31.55
29.00
27.75
28.90
28.85
29.65
10 26.35
Mean 28.26
Std. Dev. 2.22

00‘1030150010

Table 09. Edge Crush Strength of Board 2 at 1': 5 °C, RH = 59.2%.
Sample Edge Crush Strengflflbeflml

 

 

1 20.25
2 26.55
3 31.55
4 23.05
5 26.75
6 25.35
7 29.95
8 26.05
9 25.15
10 26.35
Mean 26.10

 

Std. Dev. 3.17

95

Table B-10. Edge Crush Strefingth of Board 2 at T = 5 °C. RH = 75.1%.
Sample EmCrueh Strength (lbeJln.)

 

22.55
27.75
20.95
21.35
23.00
22.45
23.05
22.75
23.15
23.20

aomummAwM-s

 

Mean 23.02
Std. Dev. 1.83

Table B-11. Edge Crush Strength of Board 2 at T = 5 °C, RH = 85.0%.
Sample Edge Crush Strength Qbefln.)

 

 

22.35
18.35
22.30
23.55
20.05
19.95
21.75
21.55
20. 05
23.30
Mean 21.32

somummawM-n

 

Std. Dev. 1.67

Table B-12. Edge Crush Strength of Board 2 at T = 5 °C. RH = 96.6%.
Sample Edge Crush Strength jlbeJin.)

 

14.90
18.95
15.50
17.85
19.05
16.05
15.55
15.85
17.75
16.65

Mean 16.81
Std. Dev. 1.49

somwmmth-s

Table B-13. Edge Crush Strength of Board 3 at T = 5 '0. RH = 14.0%.

Sample Edge Cruah Strength (160.!an
32.30
30.20
31.60
33.95
30.15
32.35
34.65
31.55
30.00
31.00
Mean 31.81
Std. Dev. 1.65

aooqamawM-n

Table B-14. Edge Crush Strength of Board 3 at T = 5 '0, RH = 34.6%.

Sample Edge Crush Strengh 11“.!an

 

 

 

1 27.45

2 29.50

3 32.05

4 31.50

5 26.75

6 29.95

7 32.05

8 28.1 5

9 27.00
10 28.50
Mean 29.29
Std. Dev. 2.04

 

Table B-15. Edge Crush Strength of Board 3 at T = 5 'C, RH = 59.2%.
Sample Edge Crush Streflth flbelln.)

 

 

1 29.50
2 29.50
3 21.05
4 25.60
5 24.00
6 30.95
7 27.55
8 26.95
9 24.05
10 23.1 0
Mean 26.23

 

Std. Dev. 3.21, 1

97

Table B-16. Edge Crush Strength of Board 3 at T = 5 ‘0, RH = 75.1%.
Sample Edgge Crush Strength (lbeJln.)

 

31.50
28.05
22.85
19.05
21.55
20.95
21.50
21.75
20.95
23.10
Mean 23.1 3
Std. Dev. 3.76

31901401111140.1154

Table B-17. Edge Crush Streggth of Board 3 at T = 5 '0, RH = 85.0%.
Sample Edgg Crueh Strength (Ibe.lln.)

 

 

1 22.50

2 22.85

3 22.55

4 21.95

5 23.05

6 22.95

7 22.00

8 23.15

9 22.05
10 20.00
Mean 22.31
Std. Dev. 0.92

 

 

Table B-18. Edge Crush Strength of Board 3 at T = 5 °C, RH = 96.6%.
Sample Edge Crush Strepgth (lbeJln.)

 

20.55
15.30
16.65
15.45
19.05
14.75
14.35
18.35
17.55
17.25
Mean 16.93
Std. Dev. 2.01

somqamAwM-A

98

Table B-19. Edge Crush Streth of Board 1 at T = 20 °C, RH = 12.4%.
Sample Edge Crueh Strength (lbaJln.)

 

 

 

1 29.65

2 32.15

3 35.15

4 29.05

5 27.95

6 30.55

7 29.05

8 30.15

9 33.15
10 30. L5
Mean 30.70

Std. Dev. 2.18

 

Table 8.20. Edge Crush Strength of Board 1 at T = 20 °C. RH = 33.6%.
Sample Edge Crueh Strength (lbe.lln.l

 

 

 

1 26.70

2 27.25

3 26. 10

4 24.80

5 28.15

6 27.45

7 28.10

8 28.00

9 29.60
10 28.00
Mean 27.42
Std. Dev. 1.32

 

Table B-21. Edge Crush Strength of Board 1 at T = 20 °C, RH = 54.9%.
Sample Edge Cruah Strength (lbeJln.)

 

25.05
26.75
27.85
23.45

25.85
26.45
22.55
24.55
24.65
25.65

Mean 25.28
Std. Dev. 1.58

accustom» 20010-

99

Table B-22. Edge Crush Strenfih of Board 1 at T = 20 “C, RH = 75.5%.
Sample Edge Cruah Strength (lbaJln.)

 

 

 

1 24.25

2 23.65

3 20.85

4 24.35

5 23.45

6 21.95

7 21.75

8 20.65

9 22.85
10 23.05
Mean 22.68
Std. Dev. 1.33

 

Table B-23. Edge Crush Stre_ngth of Board 1 at T = 20 °C, RH = 85.0%.
Sample Edge Crueh Strength (lbeJlni

 

19.95
18.85
21.15
22.55
19.95
21.30
20.05
21.00

22.00

20.53
Mean 20.74

Std. Dev. 1.09

30 mummawM-s

Table B-24. Edge Crush Strength of Board 1 at T = 20 °C, RH = 93.2%.
Sample Edge Crush Strength (lbeJln.)

 

17.95
10.90
19.30
17.65

17.00
17.05
16.75
17.75
18.00
17.85
Mean 17.82
Std. Dev. 0.81

aomumm auto-

100

Table B-25. Edge Crush Streth of Board 2 at T = 20 °C, RH = 12.4%.
Sample Edge Crush Strength 0stan

 

 

 

1 39.50

2 36.55

3 34.00

4 35.05

5 38.95

6 35.65

7 34.55

8 40.85

9 33.55
10 38.00
Mean 36.67
Std. Dev. 2.53

 

Table B-26. Edge Crush Strength of Board 2 at T = 20 °C. RH = 33.6%.
Sample Edge Crush Strength (lbaJln.)

 

 

 

 

1 30.95

2 33.55

3 34.00

4 32.05

5 36.95

6 31.85

7 32.25

8 33.45

9 36.50
10 36.00
Mean 33.76
Std. Dev. 2.10

 

Table B-27. Edge Crush Strength of Board 2 at T = 20 °C, RH = 54.9%.
Sample Edge Crush Strength (lbaJln.)

 

 

1 30.45
2 31.00
3 30.00
4 29.90
5 31.95
6 33.00
7 29.50
8 30.85
9 28.75
10 30.95
Mean 30.64

 

Std. Dev. 1.22

101

Table B-28. Edge Crush Strength of Board 2 at T = 20 °C. RH = 75.5%.

Sample Edge Crush Strermth (lba.lln.)
29.00
26.00
27.65
27.00
28.95
27.95
26.00
29.95
28.00
28.95
Mean 27.95
Std. Dev. 1.32

aomwomwa—s

Table B-29. Edge Crush Strength of Board 2 at T = 20 ’C, RH = 85.0%.
Sample Edge Crush StrenLhUbaJln.)

 

 

 

1 21.35

2 24.55

3 26.95

4 22.05

5 23.45

6 24.65

7 26.95

8 28.00

9 23.00
10 21 .95
Mean 24.29
Std. Dev. 2.35

 

Table B-30. Edge Crush Strewh of Board 2 at T = 20 °C, RH = 93.2%.

Samle Edge Crush Strflgth 0stan
21.95
19.55
20.00
21.05
20.95
20.95
22.55
21.00
19.00
18.95
20.60
Std. Dev. 1.20

3

-|
goomummwa-s
:1

102

Table B-31. Edge Crush Strength of Board 3 at T = 20 'C, RH = 12.4%.

Sample Edge Crush Strength (lbaJln.)
43.95
40.55
39.85
35.00
34.55
36.65
34.85
36.00
39.15
agoo
Mean 37.96
Std. Dev. 3.06

seawaubwna

Table B-32. Edge Crush Strength of Board 3 at T = 20 ‘C. RH = 3.6%.

Sample Edge Crush Strength (lbaJln.)
39.00
34.65
31.00
32.00
36.75
35.05
33.00
35.05
36.95
36.00
Mean 34.95
Std. Dev. 2.43

 

aomwomwa-s

Table B-33. Edge Crush Strength of Board 3 at T = 20 '0. RH = 54.9%.
Sample Edge Crush Streggth 0stan

 

 

1 31.25
2 33.00
3 31.05
4 29.85
5 31.00
6 29.45
7 30.00
8 32.05
9 33.00
10 32.09
Mean 31.27

 

Std. Dev. 1.26

103

Table B-34. Edje Crush Strength of Board 3 at T = 20 '0, RH = 75.5%.
Sample Edge Crush Strength flbaJln.)

 

 

 

1 29.65
2 28.45
3 24.95
4 25.00
5 26.75
6 25.55
7 25.00
8 26.75
9 26.00
10 30.95
Mean 26.91
Std. Dev. 2.11

 

Table B-35. Edge Crush Strength of Board 3 at T = 20 °C, RH = 85.0%.
Sample E_dge Crush Strength (lbaJlni

 

 

 

1 25.15

2 24.65

3 25.95

4 26.00

5 25.00

6 26. 10

7 25.95

8 25.45

9 25.15
10 25.00
Mean 25.44
Std. Dev. 0.52

 

Table B-36. Edge Crush Streflth of Board 3 at T = 20 °C. RH = 93.2%.
Sample Edge Crush Strength 0stan

 

1 19.95
19.00
21.95
23.00
18.05
19.95
19.00
21.00
19.05
20.85

Mean 20.18
Std. Dev. 1.52

gomwmmbwn

104

Table B-37. Edge Crush Strength of Board 1 at T = 40 °C, RH = 11.6%.
Sample Edge Crush Strength 0stan

33.95
34.95
35.00
35.00
34.00
33.50
33.55
32.00
33.75
33.50

Mean 33.92
Std. Dev. 0.92

 

aomummbwna

Table B-38. Edge Crush Strength of Board 1 at T = 40 °C. RH = 32.1%.

Sample Edge Crush Strength 0stan
30.95
28.55
29.45
30.75
31.00
29.05
31.00
32.00

29.85
30.95
Mean 30.36
Std. Dev. 1.08

3d: mummSuM-s

Table B-39. Edge Crush Strength of Board 1 at T = 40 °C. RH = 49.2%.
Sample Edge Crush Strength "hm/in.)

 

 

1 31 .00
2 30.00
3 29.00
4 28.95
5 26.75
6 27.55
7 28.05
8 26.75
9 28.00
10 27.95
Mean 28.40

 

Std. Dev. 1.36

105

Table B-40. Efle Crush Strength of Board 1 at T = 40 °C, RH = 75.4%.
Sample Edge Crush Strength (lbaJln.)

 

 

 

1 25.05

2 24.45

3 26.00

4 26.15

5 24.75

6 25.05

7 26.45

8 24.95

9 25.00
10 23.00
Mean 25.09
Std. Dev. 0.98

 

Table 841. Edg: Crush Strength of Board 1 at T = 40 °C, RH = 85.0%.
Sample Edge Crush Strewh (lbaJin.)

 

A

22.25
21.10
22.30
23.30
21.30
24.60
22.60
21.35

20.30
22. 35

Mean 22.15
Std. Dev. 1.22

an enumerate)»

Table B-42. Edge Crush Strength of Board 1 at T = 40 '0, RH = 87.9%.
Sample Edge Crush Strength (lba.lln.)

 

21 .95
23.45
22.95
21.60

20.75
23.85
19.00
24.00
21 .95
23.00

Mean 22.25
Std. Dev. 1.55

accustom): bun-

106

Table 843. Edge Crush Strength of Board 2 at T = 40 °C, RH = 11.6%.
Sample Edge Crush Strength (lba.lln.)

 

39.95
38.75
38.00
38.95
40.00
39.05
40.45
39.05
38.75
39.00

Mean 39.20
Std. Dev. 0.73

aomwomAwM-s

Table 9-44. Edge Crush Strength or Board 2 at T = 40 °C. RH = 32.1%.
Sample Edge Crush Strength (lbaJin.L

 

 

 

1 36.55

2 37.65

3 35.75

4 37.00

' 5 38.00
6 35.65

7 36.00

8 36.05

9 36.75
10 35.05
Mean 36.45
Std. Dev. 0.92

 

Table B-45. Edge Crush Strength of Board 2 at T = 40 'C, RH = 49.2%.
Sample Edgg Crush Strength (lba.lin.)

 

34.50
36.75
38.00
37.80
34.00
33.05
32.05
33.00
31 .55
3&9

ILegn 34.37
Std. Dev. 2.35

somwmmSwM-t

107

Table B-46. Edge Crush Strenih of Board 2 at T = 40 °C, RH = 75.4%.
Sample EdgiCruah Strength (lbaJin.)

 

 

 

1 29.15

2 33.05

3 30.95

4 31 .00

5 29.95

6 28.00

7 29.05

8 30.00

9 31 .25
10 30.2;

Mean 30.27

Std. Dev. 1.40

 

Table B-47. Edge Crush Strength of Board 2 at T = 40 °C, RH = 85.0%.
Sample EdggCruah Strength Qballn.)

 

 

 

 

1 25.15

2 24.50

3 23.00

4 22.00

5 28.00

6 26.75

7 27.95

8 25.55

9 24.85
10 27.15
Mean 25.49
Std. Dev. 2.02

 

Table B-48. Edgf Crush Strengm of Board 2 at T = 40 °C, RH = 87.9%.
Sample Edge Crush Strength 0stan

 

23. 15
26.75
24.95
27.05
23.55
27.85
26.00
24.00
25.50
10 24.55
Mean 25.34
Std. Dev. 1.57

DQNO’U’IAUN—l

 

108

Table B-49. Edge Crush Strength of Board 3 at T = 40 °C, RH = 11.6%.
Sample Edge Cruah Strength (IbaJln.)

 

40.00
40.15
38.95
39.15
41.00
39.00
41.05
40.95
41.00
10 40.95
Mean 40.22
Std. Dev. 0.90

(DONOJOI&QN-l

Table B-50. Edge Crush Strength of Board 3 at T = 40 '6, RH = 32.1%.
Sample Edge Crush Strength (IbaJln.)

 

38.55
39.00
38.00
39.95
37.95
38.15
38.95
39.05
38.00
39.00

Mean 38.?
Std. Dev. 0.67

SOGNGmAwM-t

Table B-51. Edge Crush Strength of Board 3 at T = 40 °C. RH = 49.2%.
Sample Edge Crush Strength (lbaJinJ

 

35.95
36.50
35.00
36.00
36.50
37.05
36.55
38.05
35.45
34.95

Mean 36.20
Std. Dev. 0.95

somwmmbwna

109

Table 8-52. Edge Crush Strerlgth of Board 3 at T = 40 ‘0. RH = 75.4%.

Sample Edge Crush Strength (lbaJln.)
29.95
34.05
31.00
32.15
33.00
30.45
35.00
31.75
29.00
28.00
Mean 31.44
Std. Dev. 2.20

 

aoouomaan-a

Table B-53. Edge Crush Strength of Board 3 at T = 40 'C, RH = 85.0%.
Sample Edge Crush Strength 0stan

 

30.20
23.00
22.45
31.70
24.60
26.30
20.35
31 .25
32.60
20.10

Mean 26.26
Std. Dev. 4.84

aomwouawua

Table B-54. Edge Crush Strength of Board 3 at T = 40 '0. RH = 87.9%.

Sample Edge Crush Strength (lbeJlnL
31.15
21.45
24.45
29.15
23.95
26.05
21.00
28.00
23.00
27.00
Mean 25.52
Std. Dev. 3.34

gowuamewna

110

Appendix C : Flat Crush Resistance

Table C-1. Flat Crush Resistance of Board 1 at T = 5 °C, RH = 14.0%.
Sample Flat Crush Resistance (Istsquare in.)

28.40
29.00
27.50
26.00
27.10
28.00
27.10
27.50
27.10
2609

Mean 27.37
Std. Dev. 0.95

 

aomwmmAwN-s

Table C-2. Flat Crush Resistance of Board 1 at T = 5 °C. RH = 34.6%.

Sample Flat Crush Resistance (lstsquare In.)
20.00
18.15
21.10
19.20
22.30
17.40
19.50
22.00

23.10

21 .00
Mean 20.38

Std. Dev. 1.85

8‘9 ooxraicnwa-t

Table C-3. Flat Crush Resistance of Board 1 at T = 5 ‘C. RH = 59.2%.
Sample Flat Crush Realstanoe (lstsquare in.)

 

16.70
18.60
17.90
15.60

19.00
18.50
17.70
20.00
16.90
1120
Mean 17.81
Std. Dev. 1.28

aomwcnm Amie-

111

Table C-4. Flat Crush Resistance of Board 1 at T = 5 ‘C, RH = 75.1%.
Sample Flat Crush Resistance (lstsquare In.)

 

 

 

1 14.80

2 15.10

3 17.90

4 15.00

5 20.10

6 16.70

7 15.90

8 16.00

9 15.40
10 16.8L

Mean 16.37

Std. Dev. 1.63

 

Table C-5. Flat Crush Resistance of Board 1 at T = 5 'C. RH = 85.0%.
Sample Flat Crush Resistance (lstsquare In.)

 

1 13.40
10.00
12.60
14.00
13.50
13.70
14.80
11.90

10.50
12.00

am mummhun

 

Mean 12.64
Std. Dev. 1.54

Table 06. Flat Crush Resistance of Board 1 at T = 5 °C, RH = 96.6%.
Sample Flat Crush Resistance (lstsquare In.)

 

 

1 8.40
2 8.60
3 8.70
4 8.70
5 _ 8.60
6 8.50
7 8.80
8 8.70
9 8.90
10 9.00
Mean 8.69

 

Std. Dev. 0.18

 

112

Table C-7. Flat Crush Resistance of Board 2 at T = 5 'C. RH = 14.0%.
Sample Flat Crush Resistance (Istsquare In.)

 

26.30
27.60
25.90
26. 10
24.55
26.00
27.90
27.40
27.90
29.05
Mean 26.87
Std. Dev. 1.32

somummth-s

Table C-8. Flat Crush Resistance of Board 2 at T = 5 'C, RH = 34.6%.
Sample Flat Crush Resistance (Istsquare in.)

 

 

1 23.10

2 22.50

3 26.90

4 21.70

5 23.80

6 21.20

7 20.30

8 22.60

9 21 .00
10 22.00
Mean 22.51
Std. Dev. 1.86

 

 

Table 09 Flat Crush Resistance of Board 2 at T = 5 'C. RH = 59.2%.

Sample Flat Crush Resistance jlstsquare in.)
19.90
17.40
19.90
18.70
21.20
19.90
18.00
17.00
17.50
10.90
Mean 18.75
Std. Dev. 1.40

somummhuua

113

Table C-10. Flat Crush Resistance of Board 2 at T = 5 '0. RH = 75.1%
Sample Flat Crush Resistance (lstsquare in.)

 

 

 

1 15.60
2 15.90
3 14.70
4 15.90
5 16.50
6 15.00
7 15.90
8 15.00
9 16.75
10 17.80
Mean 15.91
Std. Dev. 0.93

 

 

Table C-11. Fiat Crush Resistance of Board 2 at T = 5 ‘0. RH = 85.0%
Sample Flat Crush Resistance (Istsquare in.)

 

 

 

1 11.50

2 12.00

3 11.80

4 10.60

5 12.00

6 11.40

7 10.80

8 11.00

9 10.35
10 12.70
Mean 11._42
Std. Dev. 0.73

 

Table C-12. Flat Crush Resistance of Board 2 at T = 5 'C. RH = 96.6%

Sample Flat Crush Resistflce (lstsquare In.)
7.70
8.00
7.60
7.40
7.30
7.70
7.40
6.50
7.80
950
Mean 7.59
Std. Dev. 0.52

abaflamwa-t

114

Table C-13. Flat Crush Resistance of Board 3 at T = 5 ’0, RH = 14.0%
Sample Fiat Crush Resistance (Ibs.Isquare In.)

 

 

1 25.90
2 26.90
3 24.50
4 24.70
5 25.70
6 24.00
7 25.60
8 26.30
9 25.00
10 24.90
Mean 25.35
Std. Dev. 0.89

 

Table C-14. Flat Crush Resistance of Board 3 at T = 5 °C. RHI= 34.6%
Sample Flat Crush Resistance (Istsquare In.)

 

 

 

1 20.80
2 20.80
3 19.90
4 19.40
5 21.90
6 21.40
7 20.80
8 21.80
9 18.85
10 19.95
Mean 20.56
Std. Dev. 1.02

 

Table C-15. Flat Crush Resistance of Board 3 at T = 5 °C. RH = 59.2%
Sample Flat Crush Resistance (Istsquare in.)

 

16.80
17.00
15.90
17.00
16.30
16.70
15.90
15.40
16.40
16.50
16.39
Std. Dev. 0.53

3

A
goomwmmawna
:3

115

Table C-16. Flat Crush Resistance of Board 3 at T = 5 °C, RH = 75.1%

Sample Flat Crush Resistance (lstsquare in.)
1 15.80
16.90
14.00
16.20
15.90
15.10
15.80
14.90
15.80
15.00
Mean 15.54
Std. Dev. 0.81

Beaumont-wk)

Table C-17. Flat Crush Resistance of Board 3 at T = 5 '0, RH = 85.0%

Sample Flat Crush Resistance (Istsquare in.)
10.10
10.70
10.90
11.90
12.00
11.50
10.90
10.20
11.00
10.50
Mean 10.97
Std. Dev. 0.65

aomuwmawna

Table C-18. Flat Crush Resistance of Board 3 at T = 5 '0, RH = 96.6%
Sample Flat Crush Resistance (lstsquare in)

 

 

 

1 6.80
2 7.40
3 7.30
4 7.80
5 7.10
6 7.00
7 6.90
8 7.20
9 7.10
10 7~_10
Mean 7.17

 

Std. Dev. 0.28

116

Table C-19. Flat Crush Resistance of Board 1 at T = 20 '0. RH = 12.4%.
Sample Flat Crush Resistance (Istsquare in.)

34.60
33.70
35.90
36.70
35.10
36.70
33.50
34.00
36.00
35.90

Mean 35.21

Std. Dev. 1.21

 

somummbuua

Table C-20. Flat Crush Resistance of Board 1 at T = 20 'C, RH = 33.6%.
Sample Flat Crush Resistance (lstsquare In.)

 

 

 

1 28.90
2 27.80
3 29.05
4 28.20
5 28.30
6 27.00
7 26.90
8 28.00
9 29.10
10 30.00
Mean 28.33
Std. Dev. ‘ 0.97

 

Table C-21. Flat Crush Resistance of Board 1 at T = 20 ‘C, RH = 54.9%.
Sample Flat Crush Resistance (lstsquare In.)

23.80

24.50

22.10

23.20

24.10
22.45
23.50
23.35
23.10
23.00

Mean 23.31
Std. Dev. 0.72

 

anagram auto-

117

Table C-22. Flat Crush Resistance of Board 1 at T = 20 '0, RH = 75.5%.
Sample Flat Crush Resistance (lstsquare In.)

 

 

 

1 19.60
2 20.10
3 21.50
4 23.10
5 22.50
6 20.40
7 21 .00
8 19.60
9 20.40
10 19.50
Mean 20.77
Std. Dev. 1.25

 

Table C-23. Flat Crush Resistance of Board 1 at T = 20 'C, RH = 85.0%.
Sample Flat Crush Resista_nce (lstsquare In.)

 

17.50
17.40
16.30
15.30
17.00
18.05
17.50
18.00

17.40
17.70

Mean 17.22
Std. Dev. 0.84

310 mwamawM-s

Table C-24. Flat Crush Resistance of Board 1 at T = 20 'C. RH = 93.2%.
Sample Flat Crush Resistance (Istsquare In.)

 

13.90
13.30
12.00
14.05

13.50
14.00
13.30
13.05
13.45
12.95
Mean 13.35
Std. Dev. 0.61

somumm euro-s

118

Table C-25. Flat Crush Resistance of Board 2 at T = 20 °C. RH = 12.4%.
Sample Flat Crush Resistance (lstsquare in.)

 

 

 

1 33.40
2 33.90
3 34.10
4 32.50
5 33.10
6 34.60
7 31.80
8 35.40
9 33.10
10 35.00
Mean 33.69
Std. Dev. 1.13

 

Table C-26. Flat Crush Resistance of Board 2 at T = 20 ‘C. RH = 33.6%.
Sample Flat Crush Resistance (lstsquare in.)

 

 

 

1 28.70
2 27.90
3 26.80
4 29.50
5 25.90
6 28.90
7 27.90
8 29.05
9 27.10
10 26.90
Mean - 27.87
Std. Dev. 1.17

 

Table C-27. Flat Crush Resistance of Board 2 at T = 20 °C, RH = 54.9%.
Sample Flat Crush Resistance Qstsquare In.)

 

 

1 23.50
2 34.90
3 26.10
4 23.60
5 22.00
6 25.00
7 24.90
8 23.10
9 23.70
10 23.00
Mean 24.98

 

Std. Dev. 3.68

119

Table C-28. Flat Crush Resistance of Board 2 at T = 20 'C, RH = 75.5%.
Sample Flat Crush Resistance (Istsquare ML

 

19.85
18.60
23.20
18.10
21.30
22.30
21 .00
22.50
18.80
2215
Mean 20.78
Std. Dev. 1.83

aoouomawna

Table C-29. Flat Crush Resistance of Board 2 at T = 20 °C, RH = 85.0%.
Sample Flat Crush Resistance (Istsquare irfl

 

16.60
16.20
16.00
16.90
16.40
15.90
15.50
16.80
17.50
16.90
Mean 16.47

somwmmawM-s

 

Std. Dev. 0.59

 

Table C-30. Flat Crush Resistance of Board 2 at T = 20 °C. RH = 93.2%.
Sample Flat Crush Resistance JIstsguare in.)

 

10.90
11.90
11.50
11.00
10.30
10.20
11.80
12.00
10.30
11.10

Mean 11.10
Std. Dev. 0.69

somummwa-s

120

Table C-31. Flat Crush Resistance of Board 3 at T = 20 °C, RH = 12.4%.

Sample Flat Crush Resistance (Istsquare In.)
32.60
33.40
34.90
31.60
34.20
33.90
34.10
32.90
33.00
32.60
Mean 33.33
Std. Dev. 0.97

somwmmhwna

Table C-32. Flat Crush Resistance of Board 3 at T = 20 '0. RH = 33.6%.
Sample Fiat Crush Resistance (Istsquare In.)

 

 

 

1 28.90

2 27.10

3 26.90

4 27.60

5 29.00

6 29.10

7 26.30

8 25.10

9 27.20
10 27.10
Mean 27.43
Std. Dev. 1.28

 

Table C-33. Flat Crush Resistance of Board 3 at T = 20 ‘0, RH = 54.9%.

Sample Flat Crush Resistance (Istsquare in.)
22.30
23.10
22.80
21.05
23.00
25.00
21.05
20.00
23.00
22.00
Mean 22.33
Std. Dev. 1.40

Somwounbwro-s

121

Table C-34. Flat Crush Resistance of Board 3 at T = 20 '0. RH = 75.5%.

Sample Flat Crush Resistance (Istsquare Ind
22.25
19.70
21.60
20.80
20.85
19.55
22.65
21.60
20.20
10 19.00
Mean 20.82

Std. Dev. 1.21

oaqambuM-s

Table 035. Flat Crush Resistance of Board 3 at T = 20 'C, RH = 85.0%.

Sample Flat Crush Resistance (Istsquare In.)
15.30
15.90
16.00
16. 30
15.20
14.90
15.00
14.00
15.30
15.40
Mean 15.33
Std. Dev. 0.65

aoouomawna

Table C-36. Fiat Crush Resistance of Board 3 at T = 20 '6. RH = 93.2%.
Sample Fiat Crush Resistance (lbs/square In.)

 

 

1 10.80
2 10.60
3 10.10
4 9.90
5 11.30
8 11.00
7 9.95
8 9.00
9 10.90
10 9.90
Mean 10.35

 

Std. Dev. 0.69

122

Table C-37. Flat Crush Resistance of Board 1 at T = 40 '0. RH = 11.6%.
Sample Flat Crush Resistance (lstsquare in.)

 

37.90
38.20
39.20
36.10
38.05
36.40
37.50
37.50
36.20
36.10
Mean 37.32
Std. Dev. 1.07

aomummwa-A

Table C438. Flat Crush Resistance of Board 1 at T = 40 '0, RH = 32.1%.
Sample Flat Crush Resistance (Istsguare In.)

 

1 33.90
34.80
33.60
34.95
32.50
34.00
35.00
32.90

34.95
34.65

Mean 34.13
Std. Dev. 0.90

30 0040101wa

Table C-39. Flat Crush Resistance of Board 1 at T = 40 '0, RH = 49.2%.
Sample Fiat Crush Resistance (lstsquare in.)

 

30.60
32.80
33.70
31 .00

33.90
34.20
27.90
28.00
29.20
2829

Mean 30.97
Std. Dev. 2.54

snowmen euro-a

123

Table C-40. Flat Crush Resistance of Board 1 at T = 40 'C. RH = 75.4%.
Sample Fiat Crush Resistance (lstsquare in.)

 

25.60
23. 10
22.90
26.70
21.90
23.00
21 .00
23. 10
22.90
24.30
Mean 23.45
Std. Dev. 1.68

aomwamth-s

Table C-41. Flat Crush Resistance of Board 1 at T = 40 '0. RH = 85.0%.
Sample Flat Crush Resistance (Istsquare in.)

 

uh

19.90
18.80
17.90
18.10
19.90
17.90
20.00
17.50

18.50
18.00

Mean 18.65
Std. Dev. 0.95

30 cowaioibwro

Table C-42. Flat Crush Resistance of Board 1 at T = 40 'C. RH = 87.9%.
Sample Flat Crush Resistance (Istsquare in.)

 

18.05
18.60
20.00
19.95

18.10
18.30
18.30
17.90
19.00
19.85

Mean 18.81
Std. Dev. 0.84

300040101 awn-s

124

Table c-43. Flat Crush Resistance of Board 2 at T = 40 '0. RH = 11.6%.
Sample Flat Crush Resistance (lstsquare In.)

38.90
38.20
37.10
38.80
37.40
37.40
38.10
37.20
38.30
37.00

Mean 37._84

Std. Dev. 0.71

 

BOONQMAUN-i

Table C-44. Fiat Crush Resistance of Board 2 at T = 40 °C. RH = 32.1%.

Sample Flat Crush Resistance (Istsquare in.)
32.40
33.90
34.70
32.50
33.10
32.90
33.00
32.70
33.60
34.00
3338
Std. Dev. 0.75

3
.s
goomwmmawn-b

Table 045. Flat Crush Resistance of Board 2 at T = 40 ’0. RH = 49.2%.
Sample Flat Crush Resistance (Istsquare in.)

 

 

1 29.50
2 28.90
3 27.70
4 28.80
5 30.80
6 29.40
7 28.90
8 29.10
9 28.60
10 29.00L
Mean 29.07

 

Std. Dev. 0.70

125

Table C-46. Flat Crush Resistance of Board 2 at T = 40 'C, RH = 75.4%.

Sample Flat Crush Resistance (lstsquare in.)
25.90
26.00
25.00
24.60
25.00
26.50
24.95
25.00
24.80
25.20
Mean 25.30
Std. Dev. 0.62

aomuomwa-s

Table C-47. Flat Crush Resistance of Board 2 at T = 40 'C, RH = 85.0%.
Sample Flat Crush Resistance (lstsquare in.)

 

 

 

1 17.50
2 16.90
3 17.80
4 16.40
5 17.90
6 17.00
7 16.70
8 17.80
9 17.00
10 16.50
Mean 17.15
Std. Dev. 0.56

 

Table C-48. Flat Crush Resistance of Board 2 at T = 40 °C, RH = 87.9%.
Sample Flat Crush Resistance (Istsquare in.)

 

18.00
17.10
18.20
17.90
16.50
18.75
17.00
16.95
17.20
17.30

Mean 17.49
Std. Dev. 0.69

aomwmmbwn-s

126

Table C-49. Flat Crush Resistance of Board 3 at T = 40 °C, RH = 11.6%.

Sample Flat Crush Resistance Qstsquare In.)
36.80
36.00
34.50
36.90
37.70
35.95
37.50
36.50
36.80
36.90
Mean 36.56
Std. Dev. 0.91

somwmmawM-s

Table C-50. Flat Crush Resistance of Board 3 at T = 40 °C, RH = 32.1%.
Sample Flat Crush Resistance (Istsquare in.)

 

31.80
31.10
30.90
32.60
30.50
32.00
30.45
30.80
30.60
32.15

Mean 31.29
Std. Dev. 0.78

aomummwa-s

Table C-51. Fiat Crush Resistance of Board 3 at T = 40 '0, RH = 49.2%.
Sample Fiat Crush Resistance (Istsquare in.)

 

27790
27.80
29.00
26.90
27.20
27.80
27.60
27.90
27.70
27.60

Mean 27.74
Std. Dev. 0.55

aomqmmauN-n

 

127

Table C-52. Flat Crush Resistance of Board 3 at T = 40 'C. RH = 75.4%.
Sample Flat Crush Resistance (Istsquare In.)

 

23.90
22.10
23.90
23.80

gomwamawN-s
i8
8

Mean 23.25
Std. Dev. 0.69

Table C-53. Flat Crush Resistance of Board 3 at T = 40 ‘0. RH = 85.0%.
Sample Flat Crush Resistance (lstsquare in.)

 

 

 

1 15.90

2 16.90

3 15.00

4 16.70

5 15.95

6 16.10

7 16.00

8 16.90

9 17.00
10 16.50
Mean 16.30
Std. Dev. 0.62

 

Table C-54. Flat Crush Resistance of Board 3 at T = 40 '0. RH = 87.9%.
Sample Flat Crush Resistance (Qquuare in.)

 

17530
16.70
16.40
17.40
16.50
17.00
16.80
16.50
17.00
18.00
Mean 16.96

aoaqamaun-s

 

Std. Dev. 0.50

128

Appendix D : Bursting Strength

Table D-1. Bursting Strength of Board 1 at T = 5 ‘C, RH = 85%.
Bursting Strength (lbs/square in.)

 

 

 

 

Sample 1 2 3 4 Average_

1 91 100 100 91 96

2 87 80 125 105 99

3 75 90 1 15 1 15 99

4 85 102 86 100 93

5 90 96 82 70 85
Mean 94

Std. Dev. 6

 

Table D-2. Bursting Strength of Board 1 at T = 20 °C, RH = 85%.
Bursting Strength (istsquare In.)

 

 

 

 

 

Sarnjle 1 2 3 4 Average—

1 165 125 115 180 146

2 85 115 100 110 103

3 105 110 125 90 108

4 130 133 96 125 121

5 96 85 101 124 102
Mean 116

Std. Dev. 19

 

Table D-3. Bursting Strength of Board 1 at T = 40 “C, RH = 85%.
Bursting Strength (Istsquare in.)

 

 

 

 

Sample 1 2 3 4 Average_
1 121 120 100 120 115
2 102 146 115 90 113
3 95 150 112 98 114
4 145 114 100 141 125
5 120 122 112 156 128
Mean 119

 

Std. Dev. 7

129

Table D—4. Bursting Strength of Board 2 at T = 5 °C. RH = 85%.
Burstifl Strength (Istsguare in.)

 

 

 

 

 

Sample _1_ 2 3 4 Average;

1 157 185 155 150 162

2 200 175 165 160 175

3 195 160 175 225 189

4 225 187 170 180 191

5 167 180 180 165 173
Mean 178

Std. Dev. 12

 

Table D-5. Bursting Strength of Board 2 at T = 20 ‘C. RH = 85%.
Bursting Strength (Istsquare In.)

 

 

 

 

Sample 1 2 3 4 Averag£_

1 1 85 21 1 21 0 206 203

2 267 21 1 260 245 246

3 220 250 255 314 260

4 285 265 31 5 245 263

5 1 86 21 5 229 223 21 3
Mean 241

Std. Dev. 33

 

Table D-6. Bursting Strength of Board 2 at T = 40 °C, RH = 85%.
Bursting Strength (istsquare In.)

 

 

 

 

 

Sample 1 2 3 4 Averag_e_

1 254 230 265 286 259
2 264 243 236 206 237
3 242 290 260 235 257
4 222 240 298 224 246
5 266 236 240 261 251

Mean 250

Std. Dev. 9

 

130

Table D—7. Bursting Strength of Board 3 at T = 5 '0. RH = 85%.
Bursting Strenfh (Istsquare In.)

 

 

 

 

 

Sample 1 2 3 4 AM‘

1 165 195 212 205 194

2 215 200 213 196 ‘ 206

3 207 215 214 224 215

4 220 222 243 240 231

5 260 226 230 220 234
Mean 216

Std. Dev. 17

 

Table D-8. Bursting Strength of Board 3 at T = 20 ’0. RH = 85%.
Bursting Strength (lstsquare In.)

 

 

 

 

 

Sample 1 g 3 4 Averag;

1 269 270 265 250 264

2 243 255 226 230 239

3 264 258 244 285 263

4 265 258 260 255 260

5 276 253 260 241 258
Mean 256

Std. Dev. 10

 

Table D9. Bursting Strength of Board 3 at T = 40 '0, RH = 85%.

 

 

 

Bursting Strength (lbs/square In.)
Sample 1 2 3 4 Avert

1 250 240 254 266 253
2 231 256 272 280 260
3 245 232 235 236 237
4 255 245 260 246 252
5 280 305 305 282 293

Mejn 259

Std. Dev. 21

 

 

131

Appendix E: Linear Regression Model for Re-buiiding Data

Table E-1. Linear Regression Model for Claculating the ECT and FCR of Board 1 at 40 °C.

RH Aw EMC ECT FCR

10 0.1 3.23 32.94 37.33
20 0.2 4.27 31.84 35.45
30 0.3 5.15 30.91 33.88
40 0.4 5.99 30.01 32.35
50 0.5 6.90 29.06 30.73
60 0.6 7.93 27.96 28.86
70 0.7 9.24 26.58 26.50
80 0.8 11.14 24.58 23.10
90 0.9 14.74 20.77 16.61

Table E-2. Linear Regression Model for Claculating the ECT and FCR of Board 1 at 20 °C.

RH Aw EMC ECT FCR

10 0.1 4.34 29.81 32.38
20 0.2 5.57 28.79 30.72
30 0.3 6.58 27.96 29.36
40 0.4 7.54 27.16 28.06
50 0.5 8.55 26.33 26.71
60 0.6 9.69 25.38 25.17
70 0.7 11.11 24.21 23.27
80 0.8 13.12 22.55 20.56
90 0.9 16.86 19.46 15.54

Table E-3. Linear Regression Model for Claculating the ECT and FCR of Board 1 at 5 °C.

RH Aw EMC ECT FCR

10 0.1 6.07 25.62 24.65
20 0.2 7.41 24.69 23.37
30 0.3 8.46 23.96 22.36
40 0.4 9.43 23.28 21.44
50 0.5 10.42 22.60 20.49
60 0.6 11:51 21.84 19.45
70 0.7 12.84 20.92 18.19
80 0.8 14.65 19.65 16.45
90 0.9 17.88 17.40 13.36

Table E-4. Linear Regression Model for Claculating the ECT and FCR of Board 2 at 40 °C.

RH
10
20
30
40
50
60
70
80
90

Table E-5. Linear Regression Model for Claculating the ECT and FCR of Board 2 at 20 °C.

RH
10
20
30
40
50
60
70
80
90

Table E-6. Linear Regression Model for Claculating the ECT and FCR of Board 2 at 5 °C.

RH
10
20
30
40
50
60
70
80
90

Aw
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9

Aw
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9

Aw
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9

EMC
3.42
4.46
5.32
6.14
7.01
8.01
9.25
11.03
14.38

EMC
4.46
5.76
6.82
7.84
8.91
10.12
11.63
13.78
17.79

EMC
6.61
7.95
8.99
9.95
10.91
11.97
13.24
14.98
18.02

132

ECT
39.37
37.93
36.74
35.59
34.39
33.01
31 .29
28.82
24.18

ECT
36.60
35.15
33.96
32.82
31.63
30.27
28.58
26.18
21.70

ECT
30.36
29.26
28.41
27.63
26.84
25.97
24.94
23.52
21.03

FCR
37.48
35.43
33.73
32.10
30.38
28.42
25.97
22.45
15.84

FCR
32.82
30.84
29.21
27.65
26.02
24.16
21.85
18.56
12.43

FCR
25.61
24.13
22.99
21.94
20.88
19.71
18.32
16.41
13.06

Table E-7. Linear Regression Model for Claculating the ECT and FCR of Board 3 at 40 °C.

RH
1 0
20
30
40
50
60
70
80
90

Table E-B. Linear Regression Model for Claculating the ECT and FCR of Board 3 at 20 °C.

RH
1 0
20
30
40
50
60
70
80
90

Table E-9. Linear Regression Model for Claculating the ECT and FCR of Board 3 at 5 °C.

RH
1 0
20
30
40
50
60
70
80
90

Aw
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9

Aw
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9

Aw
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9

EMC
3.04
4.08
4.96
5.81
6.73
7.80
9.15
11.12
14.91

EMC
4.50
5.72
6.72
7.66
8.64
9.74
11.11
13.03
16.58

EMC
6.75
8.11
9.17
10.14
11.11
12.18
13.47
15.22
18.29

133

ECT
41.19
39.70
38.44
37.21
35.89
34.36
32.42
29.60
24.16

ECT
37.54
36.03
34.80
33.64
32.43
31.07
29.38
27.01
22.63

ECT
31.43
30.22
29.28
28.42
27.55
26.59
25.45
23.89
21.15

FCR
35.68
33.81
32.23
30.68
29.03
27.12
24.68
21.14
14.32

FCR
31.71
29.87
28.38
26.97
25.50
23.84
21.79
18.89
13.56

FCR
23.79
22.41
21.33
20.35
19.36
18.27
16.97
15.19
12.07

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