(“T‘i’ihw r?’ u’ . 7 V *- n.5,: mm W , ““0“. difnirfi'v'qg.
fir pm. 4-“ 4. , , - J3 mmv‘gfiméi - 45,;
39,5...“ffim ,; gm L. L a u “fa-.- *: mg rye”.
wan-m rm, 4% , > - 4. 7 ‘ am e 4
«.1 ":11: 3%; .. ‘ "Mal-fia- n t V . ,
was . l’ A“: 4"
n V _ .
, , .
,..4
4,44,??-
Z V0",

M ‘
u

I n

.w r 5
' p

M
r'

P“ 4413‘s .
“345:3
w‘w»? 'h

4:. “('4‘

a ‘ , , ‘ 4 J9.
; ,, "I: , ’ ‘- ‘ 1" _ . . d: ”Pig 1 32.4219!“
I . , ‘ . - mp— ‘ ' .‘ ‘ . . 2-b- . . ‘
4. 4.; "r. . " .4 ’. ‘1'“: 7 ~- '5 ' ' ‘L. mwam . '- ~ «'fimfi”
M3 .’ - ,4 , .. “$5134.51" n . . a u ; ), .ah. .4 A74; '.""C ‘1“!1'3' . . V . .~ a“ ”’13
' 4 J‘ I"; ’4‘ ' ‘ V - ' "‘"R‘" u 4 ~ ' ‘ ‘. 3;." a ark. W _ .
:5. 51;, . m- .
1 na- 1 , 4 4..- .
V " Ed’qf— ' , ”tab": (:55 5‘3“." ‘ , J":
' ~ v ‘ n‘ -~ 4 ‘- u n; ~ 4 $444.45”,
“ ' h: ‘ .4 - "a ‘1 ‘;f ‘ 3'3?:’itg‘lql,i a I .
‘. «a. 9' 4" . r 3 r. 'Irv‘~ A - '-\ l" ‘9‘)? ‘ ‘5 93' Lie". 33".; “if."1 ‘ .
. -. .ndm :3 ‘ > Jr , ‘ V "J g g «.g «‘4 4 ,
’ ‘ ‘ V12 ’ 3 r. "‘ w ‘ ”4 .“t “' 5 ‘ ‘ 1.4.1423} A
I ' a "i 4 1 , ' 4.111.: . bl‘ A_ ; . V ‘ 4 ' “Q 5.
4 *- g a.” a r .a

M:
$324?“

w '5"*i\?§;
h'i"kl“.r ..
. ' ‘3“? E?“

 

 

 

 

3. l.

4..
M"

 

4" v
. V ' > [5,1‘ .4.
% ~ “‘34 . 4 4 " 43.131“
‘v"‘ f’.‘ 41 > ', ‘4
9 A9 A a» ‘\.~I'

1. ‘ :3... A3: 1‘ .. n.
-r&;'t"'-vfa¢-"XJ' , ‘ “J ‘. - 3‘1; . 'E-‘J 39'
-' 44w . 5’ 4 24‘ 4:; 4? 4

1 «no . tun-a1“:-

‘ I I I. 'fil‘"
was -" r 4,4 gm
‘ 4.4..“ ui‘l' — at
\ffihd 4.
‘ “muffin p .r v _.
. 3.
1 - 7‘ 4,4 .1" r .p “,3"; "' 4 1;;
4 :35. f?" ”r‘ .r "”44"” > 4 .1" _ I: J 4 4 K 335 5‘ ‘,~ - 3F! ‘11 g
4 ‘J . 4 ‘ «t4 4-. ‘3 . ' :5" 4.4:
., .

’2
9.
2'

 

x ; 4
Q

.u§l‘ .
43:": <4
32%

I

,‘J
‘v

,

:-

:

.li-f
_ .
‘I

.h‘
--

'2'
3
I

 

 

'10

 

A»...

 

A...“ '-

m5
1.! .~.
, I-‘u .
4 - - . ‘ . . , . ., any,
‘ - ' , . , “pun-w»
( u . ‘ . . V . ’ 5 . -‘u ‘ ta ' 1‘ ‘
4 I ‘ . '-
.
'.
f

L
. :.r::z:£.r )2 4
.. .“L‘h'L‘J'-Y"~""}n'o'l.3,
" un-vrvnoo‘rr» ‘
.1 -. -
<

 

, r

J.”
. 6 I "n
4145’

 

lllllllmlll

1

This is to certify that the

thesis entitled

The Effect of Recycled Low Density Polyethylene

Substituted in Virgin Linear Low Density

Polyethylene as Polymer Blends on Mechanical
Properties

presented by

Prapassara Nilagupta

has been accepted towards fulfillment
of the requirements for

Mo 8 0 degree in Packaging

 

 

lee. 4/4”

Ma or professor

Susan Selke
Date January 14, 1992

 

0-7639 MS U is an Affirmative Action/Equal Opportunity Institution

 

 

LIBRARY
Michigan State
I University

 

 

 

PLACE IN RETURN BOX to remove this checkout from your record.
TO AVOID FINES return on or before date due.

DATE DUE DATE DUE DATE DUE

    
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Th

 

 

 

 

 

 

l
l l

MSU Is An Afl‘innetive Action/Equal Opportunity Institution
cmmS-nt

 

 

 

 

 

 

 

 

 

 

THE EFFECT OF RECYCLED LOW DENSITY POLYETHYLENE SUBSTITUTED IN VIRGIN
LINEAR LOW DENSITY POLYETHYLENE AS POLYMER BLENDS ON MECHANICAL
PROPERTIES .
BY

Prapassara Nllagupta

A THESIS
Submitted to
Michigan State University
In partial fulfilment of the requirements
for the degree of

MASTER OF SCIENCE

School of Packaging

1992

mmmm
THE EFFECT OF RECYCLED Low DENSITY PDLYETI-IYLENE SUBSTITUTED IN VIRGIN
LINEAR Low DENSITY POLYETHYLENE As POLYMER BLENDS 0N MECHANICAL
PROPERTIES
BY

Prapassara Nllagupta

Binary blends were prepared from recycled low-density. and virgin linear low-density
polyethylene. The blends have been evaluated in terms of seal strength, tensile stress-strain
behavior, Impact resistance, tear resistance, and crystalline melt temperature. Mechanical and
thermal data were collected in order to evaluate the influence of recycled LDPE content in the
blends on these properties. The phase behavior of the blend cannot be predicted from this
investigation. The tensile properties, tear resistance. and Impact resistance Show variations with
composition and are intennedlate between those of the parent polymers. The addition of recycled
LDPE decreases some mechanical properties, however it can be added at a certain concentration
without Significantly reducing such mechanical properties of virgin LLDPE. Such blends may have

practical utility by yielding materials having a combination of strength, stiffness. and toughness.

To my mother, Slrirat Nllagupta and my father, Pramuan Nllagupta

ACKNOWLEDGMENTS

My sincere gratitude is extended to my major professor. Susan Selke, PhD. (School of Packaging,
Michigan State University) for her guidance. Sincere appreciation Is also extended to my research
committee, Diana Twede. PhD. (School of Packaging, Michigan State University) for her support and
assistance. i would like to thank Charles Petty, PhD. (Department of Chemical Engineering) for

serving on my research committee.

i also would like to thank Don Hageri from Petosky Plastics for supporting me material in this
research, and Mike Rich from the Composite Research Center for instruction and use of the

Differential Scanning Calorimetry Equipment.

Special thanks to all my Thai friends, and my fellow graduate students for their friendships. and their

assistance which helped to make this study successful.

I world especially like to thank my family for the motivation and encouragement they gave me

throughout this course of study.

TABLE OF CONTENTS

Ust of Tables ....................................................................................................................................... vii

Ust of Figures ...................................................................................................................................... x
Chapter
1. Introduction
1.1 Industrial Plastic Scraps and Recycling ...................................................................... 1
1.2 Why Polymer Blends ...................................................................................................... 3

2. Review of the Literature
2.1 Polyethylene

 

 

 

 

 

 

 

Low-Density Polyethylene ....................................................................................... 5

Linear Low-Density Polyethylene ........................................................................... 6

2.2 Polymer blend .................................................................................................................. 7

2.3 Polymer Mlsclblllty ........................................................................................................... 7

ThermodynamicsOfPolymer-Polymer Mlscibllity ................................................... 11

Mechanical Properties ........ -- .......................................................... 12

Compatabillzing Agent ............................................................................................. 17

2.4 Previous Studies of LDPE/LLDPE Blends ................................................................... 17

3. Materials and Methods

3.1 Materials .......................................................................................................................... 19
3.2 Methods

3.2.1 Seal Strength Test .......................................................................................... 19

3.2.2 Tensile Properties Test ................................................................................... 20

3. 3. 3 Impact Resistance Test ................. - _ ......................................... 20

3. 3. 4Tear Resistance Test -- ........................................ 21

3. 3. 5 Determination of Crystalline Melt Temperature ............................................ 21

3. 3 Statistical Analysis .................................................. 21

4. Data Analysis and Interpretation

4JSeeiStrengthTestDataandAnaiysis ........................................................................... 23

4. 2 Mechanical Property Tests. ............................................................... 26

4. 2.1 Tensile Properties Test ................................................................... 27

Tensile Strength ........................................................................... 28

Modulus of Elasticity .................................................................... 32

Percent Elongation ....................................................................... 35

4.2.2 impact Resistance Test - - - ...... . ....................................... 39

4.2.3 Tear Resistance Test ..................................... 40

4.3 Differential Scanning Calorimetry (DSC) Thermal Analysis ......................................... 46

4.4 Research Limitations _ ...................................... 51

 

Table of Contents (Cont’d)

5. Conclusion .................................................................................................................................... 53

Further Experimental Suggestions ........................................................................................ 54

ListofReferences ................................................................................................................................ 55
Appendices

A Analysis of Variance of the Mechanical Properties of LDPE/LLDPE Blend .............. 57

B. Calculations of Mechanical Properties .......................................................................... 60

C. Raw Data ......................................................................................................................... 62

LIST OF TABLES

 

 

 

 

Table Page
1. Processing and Mechanical Properties of Low Density Polyethylene and Unear Low Density
Poiyethyiene ........................................................................ 2
2. Load Force Applied to Cause Seal Failure in Seal Strength Test and Tukey's Honestly
Significant Difference Test Result at 95% Confident Level ....................................................... 23
3. Tensile Strength and Tukey's Honestly Significant Difference Test Result at 95% Confident Level
(Machine Direction) ........................................................... -- .......................... 26
4. Tensile Strength and Tukey’s Honestly Significant Difference Test Result at 95% Confident Level
(Cross Direction) ........................................................................................................................ 26
5. Modulus of Elasticity and Tukey's Honestly Significant Difference Test Result at 95% Confidence
Level (Machine Direction) ......................................................................................................... 30
6. Modulus of Elasticity and Tukey’s Honestly Significant Difference Test Result at 95% Confidence
Level (Cross Direction) .............................................................................................................. 30
7. Percent Elongation and Tukey's Honestly Significant Difference Test Result at 95% Confidence
Level (Machine Direction) .......................................................................................................... 34
8. Percent Elongation and Tukey's Honestly Significant Difference Test Result at 95% Confidence
Level (Cross Direction) ............................................................. 34
9. impact Failure Weight Obtained from impact Resistance Test ................................................ 38
10. Tearing Force Applied to Cause Failure in Tear Resistance Test and Tukey's Honestly Significant
Difference Test Resdt at 95% Confidence Level (Machine Direction) ................................ 4O
1 1. Tearing Force Applied to Cause Failure in Tear Resistance Test and Tukey’s Honestly Significant
Difference Tea Result at 95% Confidence Level (Cross Direction) ........................................ 40
12. Crystaiiine Melt Temperature ObtainedfromtheDSC -- 46
13. Analysis of Variance Table at 95% Confidence Level for Forces to Cause Seal Falure ..... 57

14. Analysis of Variance Table at 95% Confidence Level for Tensile Strength
(Machine Direction) - . ....................... 57

 

vii

List of Tables (Cont'd)

 

 

Table Page

15. Analysis Of Variance Table at 95% Confidence Level for Tensile Strength

(Cross Direction) .......................................................................................................................... 57
16. Analysis of Variance Table at 95% Confidence Level for Modulus of Elasticity At Yield

(Machine Direction) ............................................................................................... 58
17. Analysis of Variance Table at 95% Confidence Level for Modulus Of Elasticity

(Cross Direction) .......................................................................................................................... 58
18. Analysis of Variance Table at 95% Confidence Level for % Elongation at Break

(Machine Direction) ...................................................................................................................... 58
19. Analysis of Variance Table at 95% Confidence Level for % Elongation at Yield

(Cross Direction) ......................................................................................................................... 59
20. Analysis of Variance Table at 95% Confidence Level for Tear Resistance Test (Machine

Direction) - - - - - - - - ...................................... 59
21. Analysis of Variance Table at 95% Confidence Level for Tear Resistance Test (Machine

Direction) ........................................................................................................................................ 59
22. Load and Extension Obtained from Seal Strength Test of Sample No. 1 ............................ 62
23. Load and Extension Obtained from Seal Strength Test of Sample No. 2 ............................ 62
24. Load and Extension Obtained from Seal Strength Test of Sample No. 3 ............................ 63
25. Load and Extension Obtained from Seal Strength Test Of Sample No. 4 ............................ 63
26. Load and Extension Obtained from Seal Strength Test of Sample No. 5 ............................ 64

27. Load and Extension Obtained from Tensile Properties Test of Sample No.i
(Machine Direction) ..... , ........................................................... 64

 

28. Load and Extension Obtained from Tensile Properties Test of Sample No.1
(Cross Direction) - ............................................. 65

 

29. Load and Extension Obtained from Tensile Properties Test of Sample No.2 (Machine
Direction) - - ........................................................... 65

 

30. Load and Extension Obtained from Tensile Properties Test of Sample No.2
(Cross Direction) - ...................................... 66

 

31. Load and Extension Obtained from Tensile Properties Test of Sample No.3
(Machine Direction) . . ........... 66

 

32. Load and Extension Obtained from Tensile Properties Ted of Sample No.3
(Cross Direction) ............................ 67

 

VIII

Ust of Tables (Cont'd)

Table Page
33. Load and Extension Obtained from Tensile Properties Test of Sample No. 4
(Machine Direction) ..................................................................................................................... 67
34. Load and Extension Obtained from Tensile Properties Test of Sample No. 4
(Cross Direction) ........................................................................................................................ 68
35. Load and Extension Obtained from Tensile Properties Test of Sample No. 5
(Machine Direction) ..................................................................................................................... 68
36. Load and Extension Obtained from Tensile Properties Test of Sample No. 5
(Cross Direction) ........................................................................................................................... 69
37. Scale Reading Value from a Tear Resistance Test of Sample no. 1 .................................... 69
38. Scale Reading Value from a Tear Resistance Test of Sample no. 2 .................................... 70
39. Scale Reading Value from a Tear Resistance Test of Sample no. 3 ............... I ..................... 7o
40. Scale Reading Value from a Tear Resistance Test of Sample no. 4 .................................... 71
41. Scale Reading Value from a Tear Resistance Test of Sample no. 5 .................................... 71
42. TheResult from Impact Resistance -_ -- _ .................................... 72

 

43. Caicrlated Tensle Properties Values from Tensile Properties Tests
(Machine Direction) .................................................................................................................... 72

44. Calculated Tensile Properties Values from Tensile Properties Tests
(Cross Direction) ....................................................................................................................... 73

Figure Page
1. Miscibie, Partially Miscibie, and immiscible Polymer Blends On a Microscopic Scale ........ 10
2. Possible Functions of Mechanical Properties Vs Two-Component Composition ................. 14
3. Homogeneity On a Macroscopic Level and a Property Profile exhibits by blends ............... 16
4. Seal Strength as a Function of % Recycled LDPE ................................................................. 25
5. Tensile Strength at Break (Machine Direction) as a Function of % Recycled LDPE ............. 27
6. Tensile Strength at Yield (Cross Direction) as a Function of % Recycled LDPE .................. 28
7. Modulus of Elasticity (Machine Direction) as a Function of % Recycled LDPE .................. 31
8. Modulus of Elasticity (Cross Direction) as a Function of % Recycled LDPE ......................... 32
9. % Elongation at Break (Machine Direction) as a Function of % Recycled LDPE ............... 35

10. as Elongation at Yield (Cross Direction) as a Function of es Recycled LDPE ....................... as.

11. impact Strength as a Function of % Recycled LDPE ............................................................ 39

12. Tear Resistance (Machine Direction) as a Function of % LDPE ............................................ 41

13. Tear Resistance (Cross Direction) as a Function of % LDPE .............................................. 42

14. Melt Profile of 50% LDPE/ 50% LLDPE from Differential Scanning Calorimetry ................ 45

15. Melt Profle of 30% LDPE/ 70% LLDPE from Differential Scanning Calorimetry ................ 46

16. Melt Profile of 20% LDPE/ 80% LLDPE from Differential Scanning Calorimetry ................ 47

17. Melt Profle of 10% LDPE/ 90% LLDPE from Differential Scanning Calorimetry ................ 48

18. Melt Profile of 100% LLDPE from Differential Scanning Calorimetry .................................... 49

19. Normal Stress and Strain Curve ............................................................................ 60

LIST OF FIGURES

 

CHAPTER I }
INTRODUCTION

Polyethylene is a thermoplastic and is the leader in total resin sales. Polyethylene film is the
lowest cost and most common plastic packaging material. in 1984. 5.4 billion lbs. [16] of low-density
polyethylene (LDPE) went into readily disposable consumer packaging, such as trash bags, grocery
sacks, shrink and stretch flm. These products finally ended up in the waste stream. Linear low-
density polyethylene (LLDPE) acquired commercial importance because of its superior mechanical
behavior compared to LDPE. Blends Of LDPE and LLDPE are now regarded as excellent materials
for film manufacture because they combine the processabillty of LDPE and good mechanical
properties Of LLDPE [1]. As the LDPE recycling rate begins to grow, this research investigates
regarding the resulting mechanical properties when recycled LDPE is blended with virgin LLDPE at

different concentration levels.

1.1 Industrial Plastic Scrap and Recycling

Recycling has become a very critical issue to everybody. The volume of solid waste has
been increasing continuously for several decades. Landfill is no longer the most efficient way to
dispose of solid waste because there are fewer sites and higher costs. Incineration, another method
of waste disposal. is also costly and pollutes the environment. Recycling seems to be an appropriate
solution to reducing the volume of solid waste to be landfilled and incinerated.

Among the materials in the waste stream, plastics are a very visible proportion and are
perceived by the public as an environmental problem. it is expected that plastics will represent
19.9% of landfill volume by the'year 2000 [7].

NO certain figure Of the industrial plastic produced or discarded each year has been
reported. in the plastics industry. material cost is a major factor of the cost of final products. Reuse

2
Of any recoverable materials such as reiect products. Offcuts. sprues, runners, flash and tops. tails
Of bottles, and trimming is an economic necessity. The higher cost of petroleum feedstock has
increased the value Of plastics to where its relncorporation into plastic has become more attractive.

Recycling Of homogeneous scrap is relatively easy in the early stages of plastic production
and converting. where it can occur intemaily within one manufacturing organization. Recycling is
very much more diflicdt in the final stage. mixed with heterogeneous consumer waste. Markets for
industrially generated plastic scrap are more established than for post-consumer.

The ln-piant scrap is that generated in manufacturing processes, production. fabrication. and
converting. usually is free Of contaminants. The scrap can be reprocessed by the manufacturer or
by an independent iirrn. it can either be sold back to the generating industry or to another industry
as a replacement for virgin material, or it can be sold as a lower grade material. Prwided
price and technical requirements can be met, there are many end market uses that can be satisfied
with recycled material. for instance, recycling LDPE film into plastic garbage bags, or recycling PVC
(polyvinylchloride) auto trim scrap into trunk mats for use in the auto industry [16]. Recycled plastics
must be cheaper than virgin plastics to be considered as a potential source Of supply for any
manufacturer. At a minimum, for recycled material to gain acceptance its price must be 25% less
than prime grade virgin material [16]. The assurance Of clean uncontaminated quality recycled
material is as important to users as is price. Plastic processors generally cannot tolerate more than
1 to 5% contamination levels acceptance [16]. The quality must be consistent and the material
guaranteed homogeneous it is for these reasons that industrial sources of waste plastic supply are
the preferred source for most reprocessors. in terms Of plastic recycling, reprocessing Of
uncontaminated plastic with virgin material. back into the same forming process or plastic product
from which it came, is considered primary recycling.

1.2 Why Polymer Blends
Mixing polymers to achieve an economic or property advantage is not a new idea. The

scientific and commercial progress in the area of polymer blends during the past two decades has
been tremendous.

Several driving forces have spurred the intense interest of polymer suppliers in developing
polymer blends. Polymer blends provide materials that are tailored to specific application
requirements, with performance that could not be duplicated by an existing single polymer. Blending
can improve physical, mechanical, and permeability properties, Chemical resistance, thennal-
perfonnance, and processablllty of polymers. it is more convenient, less expensive, and less time
consuming for the plastics producers and compounders to develop new blended products than to
develop totally new polymers. Raw materials and manufacturing equipment for blends are generally
available to suppliers from their other product lines (for example, an extruder is often used as the.
reactor), thereby reducing development risks.

Recycling is another important reason to blend plastics. Adding the plastic scrap, in pellet
form, to the virgin resin can reduce raw material cost.

The forces driving the development of polymer blends are not only from the suppliers; the
growing demand for polymer-polymer mixtures is also a driving force. The engineering polymer
alloys and blends represent one of the fastest growing polymer classes, with annual growth
expected to average 9% annually [10]. it is expected that by the year 1995, engineering polymer
alloys and blends will represent approximately 25% of the 1.1 billion kg. (2.5 billion lbs.) prolected
US. demand [10].

The plastics industry is committed to recycling. Various plastic prodUCts will be legislated
out of the market unless they are being recycled, or have recycled content. Since polyoiefins are
the most commonly used plastics, they predominate in plastics waste. Because of the similarity in
the Chemical structures of LDPE and LLDPE, their recycling leads to mixtures without separation.
Therefore. It is interesting to study the use of scrap LDPE as a substitute for virgin LLDPE in a

polymer blend-

The oblectlves of this study are:

1. To Study the effect on mechanical properties of % Recycled LDPE substitution for LLDPE in a
polymer blend.

2. To predict the phase behavior of LDPE/LLDPE blends.

3. To determine the % recycled LDPE that can be added to the blend without significantly reducing

the LLDPE properties.

CHAPTER II
REVIEW OF THE LITERATURE

In the initial stage in development of polymer blends, studies in polymer physics were
involved with the understanding of the basic properties of homopoiymers. Morphology and
properties of low density and linear low density polyethylene (LDPE and LLDPE) are reviewed at the
beginning of this chapter. The following reviews cover the basic aspects of polymer blends, for
instance, miscibility, thermodynamics, mechanical properties, and compatabliizing agents. The
previous studies about the blends of LDPE/LLDPE are reviewed at the end of this chapter.

2.1 Polyethylene

The various types of polyethylene are distinguished in terms of their density and structure
as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high density
polyethylene (HOPE). The different densities result from a variation in the crystalline packing ability
of poiyethylenes due to a difference in their level of branching. The properties and morphology of
only low and linear low-density polyethylene wIi be reviewed in this chapter.

Low-Density Polyethylene (LDPE)

Low-density polyethylene is a thermoplastic obtained through the high temperature (100
to 250 degree ceislus)and high pressure (100 to 300 Mpa) free radical polymerization of ethylene
[4]. This process produces rather frequent long-chain branching, about 15 to 20 ethyl (and a few
butyl) side-chains per 100 carbon atoms in the main-chain [6]. The chemical structure of LDPE is
lrregrlar due to the long-chain branching. The sphemlites in LDPE are markedly smaller than those
in LLDPE of similar density and melt flow index [18]. The percent crystallinlty is a function of the
amount of short-chain branching and normally falls around 30 to 40% [10]. The density of LDPE fails

between 0.918 to 0.932 gm/cc [11].

LDPE is a low cost material. it is used as a film as a malor application. it exhibits good
clarity, strength, flexibility, sealabiiity, processability, ease Of extrusion, low taste and Odor transfer
properties, and chemical lnertness. it has moderate oil and grease resistance, but has good

moisture barrier properties.

Unear Low-Density Polyethylene (LLDPE)

Linear low-density polyethylene is produced at much lower temperatures and pressures than
low-density polyethylene. it is a copolymer of ethylene with large amounts (8 to 16%) of such higher
alpha‘oiefins as 1-butene, 1-hexene or 1-octene. These copolymers have short-chain branching
Characteristic of highpressure polyethylene but have no long-chain branching [11]. Because of its
linear structure and the absence of long-chain branching, LLDPE forms a more highly crystalline
structure than LDPE. The sphemlitlc structure of LLDPE is more regular and consists of larger units
relative to that of LDPE. The density of linear low-density polyethylene is between 0.910 to 0.925
gm/CC [11].

LLDPE has acquired great commercial importance because of its superior mechanical
behavior (such as tensile strength, stiffness, toughness, impact properties, and tear properties)
compared to LDPE. it is also a low cost material. it is a better moisture barrier than LDPE. One

pTOperty where LLDPE suffers relative to LDPE is clarity. The haze and gloss of u.DPE film is poor
[11].

7
Table 1: Processing and Mechanical Properties of Low Density Polyethylene and Unear Low

Density Polyethylene [11]

 

 

 

 

 

 

 

 

 

 

 

Properties Low density
polyethylene
1. Crystalline melt 98 -115
temp. (°c)
2. Tensile yield 1300 - 2100
strength (psi)
3. Tensile strength 1200 - 4500
at break (psi)
4. Tensile modulus 25 - 41
(X 1000 psi)
5. Percent elongation 100 - 650
at break (%)
Ls; Dart drop (N/mm) . 29 - 76

 

2.2 Polymer Blends

Polymer blends refer to intimate mbtture Of two or more polymers. They are physical
mixtures of chemically distinct polymers that could exhibit homogeneous or heterogenous
characteristics on a microscopic scale, but shodd not exhibit any Obvious inhomogeneity on a

macroscopic scale.

2.3 Polymer Miacibiiity
Polymer blends can be characterized by their phase behavior as being miscible, partially

miscible, and immiscible.

1. Miscible polymer blend: appears homogeneous on a macroscopic level and is potentially
useful for industrial application. it consists of one amorphous phase, as shown in Figure is. it is

8
much like. a random copolymer in properties and processing. Among high-molecular weight
polymers, on the other hand, the requirements of similarity in structure and/or polarity are so
stringent that very few combinations of polymers have any appreciable miscibility, and miscible
blends of two polymers are quite rare. Besides, some attraction between two polymers must be
present to partially overcome the intramoiecular cohesive forces of the individual polymers.
interpolymer attractions result from specific interactions between functional groups on polymer A
with different functional groups on polymer 8. Mlscible blends will have a single, composition
dependent, glass transition temperature (TD). Ts can be calculated with the Gordon-Taylor

expression [9]:

1-9 = W.T°. + wa0b

To is the dass transition temperature of the blend
Tea and T9" are the dass transition temperature of polymers A and 8 respectively
W.l and Wb are respective weight fractions of polymers A and B in the blend

The glass transition temperature can also be predicted based on the Fox equation [9]:

l = 3M. + flu
To Toe Tab
The Fox equation predicts that the T9 of the blend is somewhat lower than does the
Gordon-Taylor equation.
2. Immiscible polymer blend: a blend that is heterogeneous on a macroscopic level. When
polymer A forms a separate phase from polymer 8, the blend would thus be considered immiscible.
immiscible blends exhibit limited attraction between polymer constituents. The interfaces between

the two Immiscible species are generally very weak. The overall mechanical properties of the blend

9
are so poor as to be of little practical utility. The immiscer blend consists of multiple amorphous

phases, as shown in Figure 1b. The polymer present in lower concentration usually forms a
discontinuous or discrete phase (domain), where as the polymer present in higher concentration
forms a continuous phase. The immiscible blends of two polymers Show two distinct Tg’s which are I
similar to those of the Isolated polymers.

3. Partially miscible polymer blend: a blend of two polymers is neither totally miscible nor
totally immiscible, but falls somewhere in between. This type Of blend can form complete miscible
blends when either polymer is present in small amounts. Phase separation is pronounced as the
mixture approaches a 50/50 blend. Where the partially miscible polymer blend is in two phases, the
phase may not have a well-defined boundary since polymer A molecules can significantly penetrate
into the polymer 8 phase and vice-versa (see Figure 1c), and often produce an unusually
advantageous combination of properties [6]. The molecular mixing that occurs at the interface of
a partially miscible two-phase blend can stabilize the domains and improve lnterfaclai adhesion,
which, in turn, explains why these two-phase blends generally have good bulk properties. It also
shows two Tg's which nonnaily fall between those of the individual polymers. The T9 of the higher
component is lowered, whereas that of the lower Tg component is raised because some molecular
mixing takes place. Most of the blends that are available in the market are this type of partially
miscible blends.

 

b. immiscible blend C. Partially miscer blend

Figure 1: Miscibie, Partially Miscibie, And Immiscible Polymer Blends On A Microscopic

Scale [10]

11
Thermodynamics Of Polymer-Polymer Miscibillty

From a thermodynamic point of view, every polymer has some solubility in every other
polymer, but the magnitude in most cases is exceedingly low. The miss governing miscible behavior
Of polymer blends are best understood in a thermodynamic context through the Gibbs Free Energy
of mixing. In order for two polymers to be miscible, the Gibbs free energy of mbdng must be
negative. The equllbrlum-phase behavior Of mixtures is governed by the free energy of mixing [3]

G = Hmlx ' ”5(0)me + 8Mme)

mix

Where G is Gibbs free energy of mixing

mix

Hm“ is enthalplc which is primarily dependent on the energy change associated with
nearest neighbor contacts during mixing and to an approximation is independent
Of molecdar weight.

Smmb‘ is the combinatorial entropy of mixing

Smmu is the excess entropy of mixing

Slam“ and 3“)me are dependent on molecular weight
From the Flory-Huggins equation [3]:

08”.“... = -R [at In A + as in e21
v1 v2

whereV| isthemolarvolumeofspeciesland o, lsvolumefraction lntheblend. VI Isproportlonal
to molecrlar weight and density: Commercial polymers have high molecdar weight The higher the
molecular weight. the higher v,. From the Flory-Huggins equation, v, is very high when compared
with 4.. therefore, asl°lm for polymer mixtures is virtually zero. Because of very small asl°lm,x, the
skim may play an Important role in overall thennodynamlc behavior. osl'lmb, is associated with

12
volume change of mixing which is generally small. Since both SPIN, and Sl'lmix tend to be zero,

in order to get a negative value of Gm“, Hm“ must be less than zero.
on = We, - £52)2 ¢1¢2

Where £5i is the solubility parameter of the pure component [3].
This equation always predicts a positive enthalpy of mixing or at best zero when 61= 62 for
mixtures of non-polar material.

I The conceptual key toward finding miscible polymer binaries is to choose polymer pairs with
chemical structures capable of specific interactions of the type leading to exothermic or negative
heats of mixing.

LDPE and LLDPE have simlar Chemical structure. They are both non-polar materials. When
blended together, dispersive interactions between weakly interacting non-polar materials lend to

positive heats of mixing, and positive Gibbs Free Energy.

Mechanical Properties

Predicting the mechanical properties of polymer blends Is a difficult task. Variations in
mechanical properties may be attributable to differences in the number of phases, size of domains,
degree of dispersion, and lnterfaclai adhesion. Frequently, the mechanical properties of a polymer
blend can be approadmated from those components. However, the properties dependent on
compaction also vary in a complex way with the partlcdar property, the nature of the components
(glass, or semicrystalllne), therrnodynamlc state of the blend (miscible or immiscible), and its
mechanical state (whether its moieClles and phases are oriented by the shaping of the material for

testing).

13
The properties of miscer polymer blends are functions of composition and to some extent

the degree of interaction between the blend components. The immiscible polymer blends propenies
will depend on the phase morphology and phase interaction as well as composition.

The typical mechanical properties vs compositional plots are step, maximum, minimum, or
linear (see Figure 2). The step-shaped plot has been commonly observed for heterogeneous phase
or immiscible polymer blends. A maximum is commonly observed for miscible polymer blends
because the specific interactions or intermolecular forces (such as hydrogen bonding, van der
Waals forces, or dipole moments) that provide miscibility enhance the packing efficiency of the
molecules. it has been reported that the mechanical properties of PPO/PS (polyethylene oxide and
polystyrene) [9] miscible material is found to be nearly linear. it has been reported as well [9] that
the partially miscible blend of PC/PETG (polycarbonate and polyethylene terephthalate glycol
monomer) shows a nearly linear relationship. A minimum relationship as a function of composition I

is reported for the partially miscible blend of PC/acryiic rubber-acryionltrlle-styrene [9].

Step

 

Mechanical property -——>

 

 

Component A, 7e

Figure 2: Possible Functions Of Mechanical Properties Vs Two-Component Composition [7]

15
Beyond the minimal level of thermodynamic compatibility, greater attractive forces between

constituents serve to enhance the resultant property profile. in general, two component polymer

mixtures may be described by the following relationship [7]:

Where P is the property value of the blend
P1 and P2 are the property values of the isolate polymer constituent
C, and Ca are the concentrations of the two polymer components
I describes the level Of synergism, or thennodynamlc compatibility of the components in

the mixture

if it has a positive value, the polymer exhibits a superior property to the weighted arithmetic average
of the constituent polymer properties and is termed synergistic. if I = 0, the property of the resulting
blend is equal to the weighted arithmetic average of the constituent properties. In this case, an
additive blend results. if it has a negative value, with properties below those predicted by the

weighted arithmetic property averages of the components, a nonsynergistic blend results.

16

 

Properly, P

Nonsynergistic
(I< 0)

 

Additive (1:0)

Synergistic
(I > 0)

     

 

 

100 Polymer 1

 

0 5?)
IL % J
100 50

Polymer concentration, %

0 Polymer 2

Figure 3: HOmogeneity On A Macroscopic Level And A Property Profile Exhibited

By Blends [10]

17

Compatibility Agents
it is possible to enhance the properties and stablity of an immiscible polymer blend.

Compatibilizing agents are those that have two distinct chemical segments, for example, block or
grafted polymers. Compatibilizing agents are added to reduce the tendency of the polymers to
separate and improve the interfacial adhesion between phases.

The A-B block copolymer is assumed to selectively dissolve block A in polymer A and
block B in polymer 8, binding the two A and 8 phases, ultimately resulting in Chemical bonds
between the two phases. This method can be utilized only when the compatibilizer polymer
segments are identical in Chemical composition to the components of the polymer blend.

An immiscible blend can also be enhanced by modification of one or both Of the polymers
to be blended. This is generally done by grafting a functional group on one polymer, to interact with

the other polymer.

2.4 Previous Studies of LDPE/LLDPE Blends

Recently, blends of various polyoiefins have been widely studied, for instance, the blends
of LDPE/HOPE, HDPE/LLDPE, HOPE/PP, NMWLPE/HMWLPE [12]. However, the studies Of the
blends between LDPE and linear LLDPE are quite few. Such blends have been studied with a view
to improve mechanical properties like impact strength, tensile strength, and processablllty or
rheological properties [1-3,5,13-19]. The previous studies on rheological properties Of such blends
showed evidence for improvement in processablllty with increase in LDPE content since the
viscosity of the melt is found to decrease with increase in LDPE content [1]. It has been reported
that the blend containing about 25% of LLDPE is the most interesting in view of the substituting of
the LDPE in the production of film by fim blowing since it shows a simlar shear viscosity at the rate
usually found in production [2,14].

LLDPE exhibits considerably higher tear resistance, impact strength, elastic modulus, and
elongation than does LDPE of similar density [18]. Such mechanical properties of LDPE/LLDPE

18
blend are always intennedlate between those of the parent polymers [1,13-14] indicating partially

miscible behavior [13-14]. Tensile strength and elastic modulus are strongly influenced by the LDPE
when LLDPE content is less than 25% [1,14]. The mechanical properties are somewhat related to
percent crystallinlty. Increase in crystallinlty generally increases tensile strength and elastic modulus,
but decreases impact strength and percent elongation [6].

Heat-sealing of PE film is sensitive to crystallinlty. High crystallinlty produces a higher and
sharper melting point and thus narrows the range of useful heat-sealablllty. Seal strength normally
depends on the degree of molecular entanglement achieved at the interface. increase in crystallinlty
causes decrease in degree of molecular entanglement at the interface. Consequently the lower
crystallinlty polymer, LDPE, favors easier heat-sealabllity [6]. Thermal analysis shows a single broad
melt peak for LDPE, but a higher and Sharper multl peak endotherrn for LLDPE of similar density

[18].

CHAPTER III
MATERIALS AND METHODS

3.1 Materials

The five blends between recycled LDPE and virgin LLDPE samples used in the present
study were provided by Petoskey Plastics Company. The composition of the film samples,
expressed as percent (weight/weight) recycled LDPE was as follows: 0%, 10%, 20%, 30%, and 50%
respectively.

Each sample was produced by the extrusion blown fflm process. After the tube passed
through the pull rolls, it was sealed to form bags. Each bag was 2-slde sewed and was open at the

top. The thickness of one side of a bag was approximately 1 mil.

3.2 Methods

The methods used for the mechanical properties study included low strain rate test (tensile
properties), and high strain rate tests (free—falling dart impact strength, and Eimendorf tear
resistance). The tensile properties, and tear strength were measured in both the machine (MD) and
cross direction (CD). The differential Scanning Calorimeter (DSC) was used to characterize the

structure of the films, and to detennlne the crystalline melt temperature of the blend components.

3.2.1 Seal Strength Test

Seal Strength tests were conducted on an lnstron Model 4201 Tensile Tester, according to
ASTM F 88-85. The type of seal failures were detennlned by nlpture or delamlnation of seals. Ten
specimens were used in each tea The test specimens were randomly out along the seal of bags.
The size or a test specimen was 1' x 6' (excluding the seal width). The lnstron Tensile Tester was
set to the following conditions:

19

20
- The initial gage length was 2 inches.

- The law separation rate was 20 in. /mln.
The data Of interest is the type of failure and the maximum force required to cause seal failure which

can be directly red from the chart recorder.

3.2.2 Tensile Properties

Tensile property tests were conducted on an Instron Model 4201 Tensle tester, according
to ASTM D 882 - 83. The type of failures were determined by rupture of test specimen. Ten
specimens were used in each test of each blend sample. The tests were performed in both machine
and cross directions. Test specimens were randomly cut from the bags. The size of a test specimen
was 1' X 8'. The film thickness of each test specimen was measured 5 times, and the average
thickness was used in the calculation of tensile properties. The machine and test conditions used
were the same as used in the seal strength test. The load, extension, and type of failure from each
tea were recorded. The tensile properties, tensile strength, percent elongation, and modulus of
elasticity were calculated.

3.2.3 Impact Strength

The Impact resistance test was conducted on a Free-Falling Dart impact Tester, according
to ASTM D 1709, Method A, staircase method. At least twenty test specimens of each sample blend
were used lneachtest Thetest specimenswere randomly cut. Thesizeofthetest specimenwas
7' x 7.5'. The C-clamp was used to hold the test specimen In place. The failure was determined by
a tear or a hole in the test specimen. The initial dart weight was recorded, and used to calculate
impact falure weight.

21

3.2.4 Teer Resistance

Tearing resistance tests were conducted on an Eimendorf Tearing Tester, according to
TAPPI T 414 om - 82. This method detennlnes the average force perpendicular to the plane of the
plastic required to tear a slnde sheet of plastic through a specified distance after the tear has been
started using an Eimendorf-type tearing tester. Ten test specimens randomly cut at both machine
and cross film directions from the bags of each sample blends were used in each test. The test
specimen size was 2.5- X 5'. Falure of a test specimen was determined when the pendulum broke
through the specimen. The scale reading from each test was recorded, and used to calculate the

tearing force.

3.2.5 Differential Scanning Calorimetry (DSC) Thermal Analysis
The crystalline melt temperatures were detennlned by Differential Scanning Calorimetry

thennal analysis on Du Pont instrument 910 080 Mode 9900. Two test specimens were prepared
from each blend sample. Each specimen was cut into small pieces; 7 to 8 mg. of sample was
measured and filled in a bottom pan. A lid was placed onthe bottom pan, and compressed closed.
The 080 was set to the following conditions:

- Sampling Interval was 1.00 second.

- Rate of scanning was 5.00°C/min. to 200°C
Two test specimens were prepared from each blend. Each test specimen was scanned twice. The
melt profles from each scan were obtained from the plotter attached to the 080. The crystalline

melt ternporatures of each blend component were detennlned.

3.3 Statistical Analysis

Amajorinterestofthls studywastodetennlnetheeffectof% recycled LDPE used see
substitute for virgin LLDPE. This was done by detennlning the % recycled LDPE that could blend
into virgin LLDPE without sacrificing the original mechanical properties of LLDPE.

22
The data was statistically analyzed by MSTAT-C (Microcomputer Program For The Design,
Management. and Analysis Of Agronomic Research Experiments). First the data was analyzed by
an Host to see if there was a significant difference in each mechanical property between each
sample blend. The Tukey’s Honestly Significant Test was later used to determine which level of

LDPE in the blend caused the differences in each mechanical property.

CHAPTER IV

DATA ANALYSIS AND INTERPRETATION

In this chapter all the test results are presented in tables. Each mechanical property is
reported, analyzed, and interpreted separately. The following parameters are determined: the highest
to the lowest level of % recycled LDPE that could be added as a substitute for virgin LLDPE,
crystalline melt temperature, and the phase behavior of the blend.

4.1 Seal Strength Test
Table 2: Load Force Applied to Cause Seal Failure in Seal Strength Test and Tukey’s

Honede Significant Difference Test Result at 95% Confidence Level

 

 

 

 

 

 

Sample %LDPE Average load Standard Tukey's
no. added (lbs.) deviation Test

Result

1 50 2.898 0.45 A

2 30 2.842 0.33 A

3 20 2.880 0.39 A

4 10 2.305 0.1 7 B

5 0 2.303 0.21 B

=l=====l= =

 

 

 

 

 

 

The seal strength of the virgin LLDPE was improved by the addition of some recycled LDPE,
but over 20% LDPE, there was no Significant improvement

The resdt from the F-Test (see Appendbt A) indicates that there is a significant difference
in forces applied to cause seal falure between each blend. Tukey's Honesty Significant Difference
Test indicates that addition of 10% recycled LDPE as a substitute for virgin LLDPE did not show a

significant increase in seal strength. The samples of 0%, 10% recycled LDPE show a significant

23

24
difference in seal strength from those of 20%, 30%, and 50% recycled LDPE. No significant

difference was observed among samples of 20%. 30% . and 50% recycled LDPE content.

Generally LDPE is a easier heat-sealability material compared to LLDPE. Heat sealing of PE
film is sensitive to crystallinlty. From the DSC melt profiles (see Figure 14-18), LLDPE which is a
more highly crystalline material than LDPE produced higher and sharper melting point and thus
narrow the range of useful heat sealing tempertures. Consequently lower crystallinlty favors easier
heat-sealing. LDPE also gives a better seal strength than LLDPE. Seal strength normally depends
on how well the molecules entanglement at the Interface is achieved. LDPE has more amorphous
regions when commred to LLDPE. Therefore, as the LDPE content in the blend increases, the
amorphous regiOns In the blend increases as well. When there exists higher amorphous region In
the blend, more molecules entanglement at the interface can be achieved when heat sealing, and
higher seal strength results.

No certain relationship (maximum, linear, or minimum) between % recycled LDPE and seal
strength was observed. in particular for the seal strength the LDPE exerts a greater influence on this
property only for contents of LDPE greater than 10 % (see Table 2). From 20% up to 50% LDPE
content there appear to be a slow increase but it was not found to be statistically significant.
Therefore, the phase behavior of the blend can not be detennlned from this test. However, recycled

LDPE can be added up to 50% to achieve higher seal strength than 100% virgin LLDPE.

Forces its.)

25

 

 

 

 

 

50 30 20 10 0

% Recycled LDPE Content

Figure 4: Seal Strength As A Function of % Recycled LDPE

4.2 Mechanical Property Tests

The effect of recycled LDPE added as substitute for virgin LLDPE in blown films on the

mechanical behavior at low and high strain rates was Investigated. The following properties were

calculated: tensile strength. elastic modulus, percent elongation, tearing strength, and impact failure

weight

4.2.1 Tensile Properties Test

Tensile Strength

Table 3: Tensle Strength and Tukey's Honestly Significant Difference Test Result at 95%

Confidence Level (Machine Direction)

 

 

 

 

 

 

 

 

%LDPE Tensile Standard Tukey's
Sample added strength at deviation Test Result
no. break
(98')

1 50 37449 355.70 C

2 30 4043.2 303.66 BC

3 20 4322.4 319.49 AB

4 10 4506.3 300.44 A

5 0 4331.7 436.82 AB l

 

 

 

 

 

Table 4: Tensile Strength and Tukey's Honestly Significant Difference Test Result at 95%

Confidence Level (Cross Direction)

 

 

 

 

96LDPE Tensile Standard Tukey's
Sample added strength at deviation Test Result
no. yield
(98')
1 50 2998.9 130.33 A
2 30 3013.7 298.72 A
3 20 3180.3 181.07 A

 

 

 

 

 

Tensile Strength (psi)

4900

4700 '-

4500

4300

4100

3900

37m

27

 

 

 

 

3500

 

50 30 20 10 0

% Recycled LDPE Content

Figure 5: Tensile Strength at Break (Machine Direction)

As A Function of % Recycled LDPE

Tensile Strength (psi)

4000

3000

2000

1000

28

 

 

 

 

 

as Recycled LDPE Content

Figure 6: Tensile Strength at Yield (Cross Direction)
As A Function of 96 Recycled LDPE

29
Tensle strength is a measure of the maximum load carrying capability of the material. The

calculation of this value is in Appendix B. Tensile strength at break was reported in the machine
direction because the maximum load was found at break point. Tensile strength at yield was
reported in the cross direction because the maximum load was found at the yield point.

F-test restlts (see Appendbt A) show that there is a significant difference between tensile
strengths at break. but there is no significant difference between tensile strengths at yield. The
addition of 20% LDPE and below decrease the tensile strength at break of virgin LLDPE, but at 30%
LDPE, there was no significant decrease. Further analysis, Tukey's Honestly Significant Difference
Test. indicates the difference in tensle strength at break to be between the sample of 50% recycled
LDPE and the samples of 0%. 10%, and 20% recycled LDPE.

The recycled LDPE has a significant influence on tensile strength only in the machine
direction. it can be added as a substitute for virgin LLDPE up to 30% (see table 3) for the blend to
still have no significant difference in tensile strength from 100% virgin LLDPE.

No certain relationship between 96 recycled LDPE and tensle strength in the machine and
cross direction was observed. Therefore. phase behavior can not be determined from tensile
strength test.

Normally, LLDPE exhibits higher tensle strength than does LDPE (see Table 1). LLDPE has
longer main chains or less branches and this makes LLDPE more crystalline than LDPE. The
molectles in LLDPE tend to pack into the same lattice. The polymer molecdes of the linear
structure PEfoided backandforth uponitselfinafoided lameliatypeofstructure. There exists
more tie moiecdes connecting the iameiiae of LLDPE together. Therefore. LLDPE is capable of
withstanding more load than LDPE. As mentioned in chapter 2. that the properties of the principle
component largely detennlnethe properties ofthe blend. This explains whywhen thereexlsts more

LLDPE content. the blends exhibit higher tensile strength.

Modulus of elasticity

Table 5: Modulus of Elasticity and Tukey's Honestly Significant Difference Test Result at 95%

Confidence Level (Machine Direction)

 

 

 

 

 

 

 

 

Sam pi e %LDPE Modulus of Standard Tukey’s
added elasticity deviation Test Result
no.
(95')
1 50 607.6 39.5 A
2 30 572.7 34.5 A
3 20 602.4 41.9 A
4 10 553.2 109.9 A
5 0 579.6 66.4 A
M

 

 

 

 

 

 

Table 6: Modulus of Elasticity and Tukey's Honestly Significant Difference Test Result at 95%

Confidence Level (Cross Direction)

 

 

 

 

 

 

 

 

 

 

 

88mm %LDPE Modulus of Standard Tukey's
added elasticity deviation Test Result
no.
(08')
1 50 24440 7717.9 A
2 30 21430 4939.3 A
3 20 22910 3997.3 A
l 4 10 13400 ' 3310.3 A
I '5 0 21300 3599.4 J A ||

 

Elastic Modulus (psi)

31

 

 

 

96 Recycled LDPE Cement

Figure 7: Modules of Elasticity (Machine Direction)

As a Function of 91. Recycled LDPE

 

Elastic Modulus (psi)

32

 

 

 

 

 

$6 Recycled LDPE Cement

Figure 8: Modulus of Elasticity (Cross Direction)

As A Function 01% Recycled LDPE

33
Moddus of elasticity. alternately referred to as Young's Modulus, can be determined from

the ratio of stress to corresponding strain below the proportional limit of a material (see Appendbt
B). It is a measure of force required to deform the plastic by a given amount and is thus a measure
of the intrinsic stiffness of the film.

Normally, LLDPE has almost twice as high a modulus of elasticity as LDPE [11]. It is
Interesting that addition of LDPE did not significantly decrease this property in the blends. It is
possible that addition of recycled LDPE is more sensitive to the change of tensile strength than to
the change of modulus of elasticity.

The result from F-test (see Appendix A) shows that there is no significant difference in
modulus of elasticity between the blends. The addition of some recycled LDPE did not significantly
decrease the modulus of elasticity of virgin LLDPE in either the machine and cross directions.
Modulus in a pure polymer. each segment of the polymer molecules has a certain relative freedom
to rotate and migrate. When LDPE is added into LLDPE. some polymer molecules of LDPE lie
directly adlacent to molecules of LLDPE. Since both LDPE and LLDPE are similar in structure, the
ability to rotate and migrate of LLDPE is not restricted by LDPE. The explains why there is no
change in modulus of elasticity of the blends no matter how much LDPE is added.

The phase behaviors really cannot be determined at this point mcause there is no
significant difference In this property between each blend. The only conclusion that can be made
here is that up to 50% recycled LDPE can be added as a substitute for LLDPE to yield the same

moddus properties as does virgin LLDPE.

Percentelongation

Table 7: Percent Elongation and Tukey's Honestly Significant Difference Test Result at 95%
Confidence Level (Machine Direction) '

 

 

 

 

 

 

 

Sample %LDPE Percent Standard Tukey's
no. added elongation deviation Test Result
1 50 605.6 97.88 B
2 30 707.4 41 .04 AB
3 20 753.4 38.61 A
4 10 764.1 47.42 A
5 0 766.5 43.71 A
h:=a=l— ‘ =1

 

 

 

 

 

 

 

Table 8: Percent Elongation and Tukey's Honestly Significant Difference Test Result at 95%
Confidence Level (Cross Direction)

 

 

 

I Sample %LDPE Percent Standard Tukey's
no. added elongation deviation Test Result

 

 

 

 

1 50 988.6 28.35 A
2 30 947.4 57.38

3 20 33.8 . 35.31 A
4 10 954.1 63.90 A

 

 

>

948 4 45.23

 

 

 

 

 

Percent Elongation

 

 

 

 

 

50 30 20 10 0

% Recycled LDPE Content
Figure 9: 96 Elongation at Break (Machine Direction)

AS A Function of % Recycled LDPE

Percent Elongation

 

1400

1mm -

 

 

 

50 30 20 10 0

$6 Recycled LDPE Content

Figure 10: % Elongation at Yield (Cross Direction)
As A Function 01% Recycled LDPE

 

37
The addition of some recycled LDPE decreases the percent elongation only In machine

direction of virgin LLDPE. but below 30% LDPE. there was no significant decrease.

The test results of Host (see Appendix A) show that there is a significant difference
between percent elongation at break of the blends in the machine direction. The Tukey’s Honestly
Significance Difference Test indicates that the significant different in percent elongation at break of
the blends in the machine direction is between the sample of 50% LDPE and the samples of 20%.
10%. and 0% LDPE. There is no significant difference in percent elongation in the machine direction
among the sample of 30%. 20% 10%, and 0% LDPE. There is no significant difference between
percent elongation at yield in the cross direction.

The percent elongation at break is the percent increase in length produced in the gage
length of the test specimen at the moment of mpture of the test specimen. it is a measure of the
film’s ability to stretch. Elongation represents the extent to which polymer molecules slide pass each
other before separating completely at catastrophic failure. it decreases as crystallinlty increases. This
Is due to the decreasing mobility of the system. It has been reported [18] that the spherulitic
structure of LLDPE is more regular and consists of larger units relative to that of LDPE. Such
structure should result in lower elongation and impact strength. The percent elongation increases
when the LLDPE content increases. The increase in crystalline content in the blends does not
decrease the percent elongation as it should do.

The increase of percent elongation at break in the machine direction can be explained by
structural differences in the amorphous phase. The longer main chains and the narrower length
distribution of LLDPE than in the LDPE. having longer branching. results in more tie molecules In
the LLDPE than in LDPE. This structure of LLDPE is responsible for the ductility exhibited by LLDPE.
Therefore. the increase in percent elongation at break restlts from the reinforcement effect mainly
contributed by the more ductile LLDPE. Recycled LDPE in this case can be added up to 30% to

obtain the same value of elongation obtained by 100% virgin LLDPE.

38
The phase behavior cannot be detennlned because no significant difference in the cross

direction or certain relationship between modulus of elasticity and % recycled LDPE content was

found.

4.2.2 Impact Resistance Test

Table 9: impact Failure Weight Obtained From impact Resistance Test

 

 

 

 

 

 

Sample %LDPE impact failure
no. added weight
(lbs-l
) 1 50 59
2 30 77
3 20 86
r 4 10 199
L 5 o .9. l

 

 

 

The impact failure weight (mass). in this case. is the expressed in terms of the energy that
causes 50% failure of the specimens tested. it is a measure of the film's ability to withstand shock
loading.

Adding recycled LDPE to the virgin LLDPE was found to decrease impact resistance. Since
only one impact falure weight was obtained from each test. therefore. statistical analysis was not
employed. From Figure 11 impact falure weight decreases when the percentage of LDPE is
decreased from 50% to 10%. in this case the amount of recycled LDPE can be added up to 10%
as a substitute for virgin LLDPE without sacrificing the impact strength.

Impact Failure Weight (gm.)

250

 

 

 

 

 

50 30 20 10 0

% Recycled LDPE Content

Figure 1 1: Impact Failure Weight As A Function

01% Recycled LDPE

4.2.3 Tear Resistance Test

Table 10: Tearing Force Applied to Cause Failure in Tear Resistance Test and Tukey's

Honestly Significant Difference Test Result at 95% Confidence Level (Machine Direction)

 

 

 

 

 

 

Sample %LDPE Average Standard Tukey’s
no. added tearing force deviation Test Result
(lbs)
1 50 918.2 328.93 C
2 30 916.6 244.85 C
3 20 1224.3 189.37 C
4 10 1969.8 378.1 8
5 0 2417.2 506.99 A

Table 11: Tearing Force Applied to Cause Failure in Tear Resistance Test and Tukey’s

 

 

 

 

Honestly Significant Difference Test Result at 95% Confidence Level (Cross Direction)

 
    
 
   
 

 

Average
tearing force
(lbs)

 

   

7000.4

 

   

8491 .5

 

   

9558.9

 

 

 

 

 

 

 

 

Tearing Force (lbs.)

41

 

3000

 

 

 

 

50 30 20 10 0

% Recycled LDPE Comem
Figure 12: Tearing Force (Machine Direction) As A Function

of as Recycled LDPE

Tearing Force (lbs.)

42

 

13000

12000 -

 

 

 

% Recycled LDPE Cement

Figure 13: Tearing Force (Cross Direction) As A Function

of % Recycled LDPE

 

43
The F-tea (see Appendix A) results indicate that there is a significant difference in

tearing force in both machine and cross directions. Adding 10% of the recycled LDPE reduces
the tear resistance in the machine direction of virgin LLDPE. Below 20% LDPE, there is no
significant decrease in tearing force in the cross direction. Further analysis for significant
difference indicates that the significant difference in tearing force in the machine direction is
between the sample of 50% LDPE and the samples of 10%, and 0% LDPE, the sample of 30%
LDPE and the samples of 10%. and 0% LDPE. the sample of 20% LDPE and samples of 10%,
and 0% LDPE. the sample of 10% LDPE and the sample of 0% LDPE. The is no significant
difference in tearing force between the sample of 50% and the sample of 30%. and 20% LDPE.
There is a significant difference in tearing force in the cross direction between the sample of 50%
LDPE and the samples of 30%. 20%, 10%. and 0% LDPE. There is no significant difference in
tearing force among the samples of 30%. 20%, 10%. and 0% LDPE. '

Adding 10% recycled LDPE significantly reduced tearing force in the machine direction,
whle‘in the cross direction. recycled LDPE can be added up to 30% without reducing the tearing
force from that of 100% virgin LLDPE.

Normally, tear resistance increases when % crystallinlty Increases [6]. In both the machine
and cross directions of the film, tearing force increases when there is more crystalline material,
LLDPE. content in the blend. Tearing force in the cross direction is greater than that in machine

direction because of the film is oriented in the machine direction.

44

4.3 Differential Scanning Calorimetry (DSC) Thermal Analysis

Table 12: Crystalline Melt Temperature Obtained From The DSC

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Sample % LDPE Crystalline mdt Crystalline melt

no. added temperature of LDPE (°c) temperature of LLDPE (’0)
First scan Second scan First scan Second scan
1 50 - 110.3 - 1205,1231a

1 50 1 15.2 110.8 122.9 122.5

2 30 115.2 110.6 122.4 121.7 I

2 30 115.7 111.1 122.9 122.5

3 20 115.9 110.7 122.7 122.1

3 20 1 15.5 110.9 122.9 122.9

4 10 116.4 110.8 123.1 122.4

4 10 116.2 111.3 123.0 123.4

5 0 116.1 112.0 112.9 122.5

J 5 0 1 16.2 116.2 123.3 122.7

 

 

 

a. Two peaks were observed

Sunpuuam1vaxt

Size: 5.0000 mg DSC
Method S’s/min. to me
Comment: Reecan of 50% LDPE/ 50% LLDPE

File: SaMpiet.02

Operabr: Prapasaara Nlegupta
Rm Date: 07/10/91 15:15

 

 

 

 

 

 

 

-0.35
~0.404
a
\
§ -o-45-* N
\
3 l
E
«,—o.504
8 123.05%:
I:
43.55.) 110.31":
4 120.43'0
-0.so - - . - . ._ ,. - , - 4~4 , ._,
20 40 so so too 120 140 100 130 200
\ Temperature (°c)
GeneralV2.2ADupont9900

Figure 14: Melt Profle Of 5096 LDPE/50% LLDPE From Differential Scanning Calorimetry

Sample: 30LP/70LL File: Samplsz.02

Size: 7.6000 mg DSC Operator: Prapsssars Nllagupta
Method S‘s/min. to 200's Run Date: 07/24/91 13:09

Comment: Rescsn of 30% LDPE/ 70% LLDPE

0.05

 

0.00

F—

 

. Heat Flow (cal/sec/g)

111. 10°C

 

122. 2'0

 

 

 

40 ' so so 160 ' ta'o ' tie ' 130

Temperature (’0)
General V2.2A Dupent 9900

Fiona 15: Melt Profile Of 30% LDPE/ 70% LLDPE From Differential Scanning Calorimetry

lo)

lieatfiournxfl/sec

47

Sample: ' 20LP/80LL

Size: 6.7a!) mg DSC
Method S's/min. to 200's
Comment: Rescan of 20% LDPE/ m LLDPE

f-‘ile: Sample3.02

Operator: Prapsssara Nllagupta
Run Date: 07/24/91 12:02

 

 

 

 

 

 

0.05
1
0.00-l
-o.0sJ
—o.104
-l

tto.s7°c
'-0.15-1
.l
-0.204
122.ss°c
.l
-o.as . . - .T. - 1 f . I
20 40 so so too 120 :40 too
iswnpennuna(°c)
GeneralV22ADupont99m
Scannhu3Cknonnunni

Pig's 16: Melt Profie Of 20% LDPE/ m LLDPE From Differential

Heat Flow (cal/sec/ol

Sumph:u1Pflle Rh:Sumph402
Size: 6.2000 mg DSC Operator: Prapssssra Nllagupta
Method S‘s/min. to 200’s Run Date: 07/24/91 10:50

Comment: ResceneftO%LDPE/90%LLDPE

0.05

 

 

ml (—

4 111.30":

 

123 . 38°C

 

 

 

-0.2s . . . f . T . r

20 40 so so 160 120 140 180

Temperature (’0)
General V2.2A Dupent 9900

Flgue 17: Melt Profle Of 10% LDPE/ 90% LLDPE From Differential Scanning Calorimetry

Sample: tinLL Fla: W
an: ozone mg DSC Operator: Prepeseara Mlagupta
Method S‘s/min. to m Ran Date: 07/24/91 10:50

Commenckeeanefim'liLLDPE

 

0.05--i

 

Heat Flow (cal/sec/g)
i

9
as
a

 

 

remove

 

 

 

Teniperatire (’c)
MWMW‘

FiglaeteszthflsdlmunPEFrornDiisrsrtlalScaMIngorhlsuy

50

Polyethylene is a semi-crystalline theme-plastic polymer. Upon the application of heat, it
undergoes a process of fusion. or melting, where the crystalline character of the polymer is
destroyed. While polymers melt over a temperature range due to differences in the size and
regularity of the individual crystallites. the melting point of the polymer is generally reported as a
single temperature where the melting of the polymer is complete.

Blending recycled LDPE as a substitute for virgin LLDPE did not change the crystalline melt
temperature of virgin LLDPE. At least two crystalline melt temperatures were observed from each
blend. indicating that LDPE and LLDPE did not mbt at the molchar level.

lmerestlngiy. only the DSC thermogram 50%LDPE/50%LLDPE (see Figure 14) exhibits one
crystalline melting peak of LDPE and two crystalline peaks of LLDPE. The rest of the DSC
thermograms obtained from 30% LDPE/70% LLDPE (see Figure 15). 20% LDPE/80% LLDPE (see
Figure 16), 10% LDPE/90% LLDPE (see Figure 17). exhibit one crystalline melting peak of each
component. it should be noted that the DSC thermograms are from the rescan of the specimen after
it was cooled (recrystallized). There are several reasons to explain why there is only one crystalline
melting peak of LLDPE when there is more LLDPE content in the blends. One explanation is that
the temperature difference between 121 and 123 degree ceislus ls only 2 degrees. it is difficult to
detect the difference in morphology of the same material from such a small temperature difference.
A second reason is because the rate of scanning is to fast to detect the difference in morphology.
The DSC thermogram obtained from 100% LLDPE exhibits two melt temperatures at 116.2% of
LLDPE and at 122.7°c of LLDPE. This indicates that there might be contamination of LDPE in LLDPE
during processing.

in all cases. crystalline melting points of LDPE obtained from the first seen are
approximately 5 degree celslus more than what are obtained from the second scan. The lower
values from second scan indicate less-complete recrystallization under the cooling conditions
imposed in the test than was obtained under the original condition. There is no difference in the
crystalline melting point of LLDPE obtained from the first and the rescan.

51
The melt profile of LDPE is much broader than that of LLDPE. This means that LDPE has

a broader molecular weight distribution. The low molecular weight molecules melt first, and the
highest molecular weight molecules melt last The molecules of LLDPE have a relatively constam
molecular weight. Thus. LLDPE exhibits a nice sharp melting peak. The consequence of the broader
melt profile of LDPE is that it allows quite a broad window In which to operate the heat sealing
operation. Moreover. the areas under the melt endothenn also Indicate the amoum of each
component in the blend.

Mlscible blends show a single. composition-dependent Ts' reflecting the mixed environment
of the blend; two phase blends. on the other hand. show two Tg’s characteristic of each phase. For
miscible systems containing a crystallizabie component, a separate crystalline phase of that
component can form. in case of LDPE/LLDPE blend. crystallizabie polymer component, two
crystalline phases were observed. but no certain conclusion associate with phase behavior can be
made. The multiple crystalline melt temperatures only tell that there were two separate crystalline
phase formed in the blend. The two poiyethyienes are different in morphology.

From the results of mechanical and thermal properties of the recycled LDPE/virgin LLDPE
blend. the blends tend to exhibit partially miscible behavior. It is not possible that the blend of these
two polymer will exhibit miscible behavior, because both LDPE and LLDPE have no chemical
structure capable of imeracting in specific ways to cause an exothermic heat of mixing. They are
thennodynamlcaiiy immiscible. because both polymers are nonpolar polymers. Nonpolar polymers
are gemraiiy more attracted to themselves than to other polymers, assuming Hmb‘ is usually
positive. Therefore. Gibbs free energy of mixing turns out to be positive. But since LLDPE and LDPE
are chemically compatible. they can at least exhibit partially miscible behavior.

4.4 Research Limitations
1. It is the glass transition temperature. not the crystalline melt temperature that detennlnes the
phase behavior of polymer blends. instead of determining the crystalline melting point, the glass

52
transition temperature should have been detennlned.

2. The deviation of the crystalline melting point of the same blend might result from the method of
cooling 9 test specimen and machine. Most of the rescans of each test specimen were done after
the temperature. in both machine and test specimen went downto ambiem temperature. or not too
much above the ambient temperature. The cooling process was moMy done by using water, but
there were several times that the cooling process was done by using liquid nitrogen. Cooling by
liquid! nitrogen made the temperature go down a lot faster than by water. The difference in rate of
cooling down the system might make the polymer co-crystailine and has some effect on the
deviation of crystalline melt temperature.

3. Measurementswere madeoniyofblendsof0t050% LDPE, notthewhoie rangeof0t0100%.
It Is not therefore, totally correct to conclude the phase behavior of the blend from the tendency

ofthedataobtainedfromthebiendof0t050% LDPE component

 

CONCLUSIONS

The following conclusions are based on the data collected from the blends of 0% to 50%
recycled LDPE only. These conclusions should not be applied to the blends of 0% to 100% recycled
LDPE.

1. The tensile strength, percent elongation, impact resistance. and tearing force of polymer blends
tend to reflect a composition weighted average of the properties possessed by LDPE and LLDPE.
2. Recycled LDPE improves seal strength in concentrations above 10%, but over 20% there was no
further significant improvement.

3. Tensfle strength of the blends Is more influenced by LLDPE. Recycled LDPE can be added up
to 30% as a substitute for virgin LLDPE without reducing tensile strength from virgin LLDPE.

4. Recycled LDPE added as a substitute for virgin LLDPE has no effect on modulus of elasticity up
to 50% LDPE.

5. Recycled LDPE can be added up to 30% as a subwtute for LLDPE without reducing percent
' elongation from virgin uses.

6. Recycled LDPE added as a substitute for virgin LLDPE reduces the impact resistance of virgin
LLDPE.

7. Adding 10% recycled LDPE decreases the tearing force in the machine direction.

8. Recycled LDPE can be added as a substitute for virgin LLDPE up to 30% to yield no difference
in tearing force in the cross direction. I

9. Recycled LDPE added as a substitute for virgin LLDPE did not change Tm of virgin LLDPE.

10. The phase behavior of LDPE/LLDPE blends cannot be determined from this study.

53

Further Experimental Recommendations

The determination of phase behavior of polymer blends cannot be made accurately from
the data obtained from the range of 0% to 50% LDPE In the blends. What should be done is to vary
the % LDPE (from 0% to 100%) or % LLDPE (from 100% to 0%) in the blend. In this way, the
tendency of the relationship between each mechanical property and the component could be
observed in a broader range of data. The phase behavior can as well be detennlned by the glass
transition temperature of the polymer blends.

For polymer blends in which both components are crystalline or semi-crystalline polymers,
the percent crystallinity of polymer blends plays an importam role on the mechanical properties of
the blends. Since both LDPE and LLDPE are semi-crystalline polymers. it is Interesting to study the
percent crystallinity of the polymer blends between these two components. The percem crystallinlty
of the blends can also be used to explain the mechanical behavior of the polymer blends. The glass
transition temperature and the percent crystallinlty of polymer blends can be simply done by
Differemial Scanning Calorimetry. For more accuram determination of crystalline melt temperature.
the rate of scanning should be slower in order to get nicer peaks. It is recommended to change the
scanning rate from 5 degree ceisius per minute to 2 degree celsius per minute.

This study only investigated the potential of recycling scrap LDPE as a substitute for virgin
LLDPE as a polymer blend. Comparing the mechanical properties of such polymers as coextruslon
film with those of the blend is also lmeresting to study.

The LDPE used in this study is clean scrap. Rs-use of clean and unmixed plastic scrap is
not too complex to do. But a mixture of LDPE and LLDPE often occurs in plastic waste. and the
opportunity to commingle them affects the possibility of recycling such low cost material. Although
it is expected that post-consumer blends would periorrn similarfly, it is recommended to study the
effect of post-consumer recycled LDPE/LLDPE blends.

LIST OF REFERENCES

LIST OF REFERENCES

1. Abraham, 0., George. E. K, and Francis, D. Joseph, ”Rheological Characterization of Blends of
Low Density with Linear Low Density Polyethylene Using 3 Torque Rheometer,‘

gur. dem. J. 26. 2 (1990), pp. 197-200

2. Aciemo, D.,Curto, 0., La Mantia, F. P.. and Valenza, A.. “Flow Properties of Low Density/Unear
Low Density Polyethylene," Psalm. Eng. Sci. 26, 1 (1986), pp. 28-33

3. Barlow, W. J.. and Paul. D. R., 'Polymer Blends and Alloys - A Review of Selected
Considerations," Paym. Eng. Sci. 21, 15 (1981), pp. 985-995

4. Sever. 3. Michael. W. Vol- 5. Massachusetts.
pp. 3782-3784

5. Bhateja. SK, 'Thermal. Mechanical, and Rheological Behacior of Blends of Ultrahigh and Normal-
Molecular-Weight Unear Poiyethyienes,‘ Polym. Eng. Sci. 23, 16 (1983). pp. 888-893

6. Deanin, D. Rudolph,P r t r Pr rti A i ti n ,Massachusetts, pp. 363-365.
416-416

7. Fox, W. D. Allen, R. B., and General Electric Company, ”Compatibility” W
m Englnfiring, 2"d Edition, Vol. 3, pp. 758-775

8. Franklin Associates, Ltd., ti n M n I W t in hit
2999. Prairie Village. Kansas (1986)

9. Kenskkula. H. Paul, D. R. Barlow, J. W. 'PolymerBiends' WW
Engineering 2"“ Edition, Vol. 12 pp. 399-452

10. Kuebzle, S. Y., and Chemical System Inc., in n M t H k Vol.2, ASM
lntemational, pp. 487-492. 510

11. Mills, D. C., "Low-density Polyethylene," M Pi i n , issue mid October
(1991), pp. 56-70, and 510

12. Nadkami, v. M.. and Joe. J. P.. W Vol. 4.
pp. 81-91. and 121-148

13. La Mantia, F. P. and Aciemo, D., "Mechanical Properties of Blends of Low Density with Unear
Low Density Polyethylene.“ Eur, Eglym. J. 21, 9 (1985). pp. 811-813

55

56
Ust of References (Cont’d)

14. La Mantia, F. P., Valenza, A., and Curto, 0., "Influence of the Structure of Linear Density
Polyethylene on the Rheological and Mechanical Properties of Blends with Low Density
Polyethylene,‘ PclymEng. Sci. 22, 8 (1986), pp. 647-652

15. La Mantia, F. P., Valenza, A., and Aciemo, D., 'Elongation Behavior of Low Density/Linear Low
Density Polyethylenes,” Pclm. Eng. Sci. 28, 2 (1988). pp. 90-95

16. Resource Integration System, Ltd., Mgrkct Stucy Fcr Rmyciamc Piggicc; Background Report,
Toronto, 1987, pp. vii-viii, and 11

17. Shishesaz, M. R., and Donateili, A. A., ”Tensile Properties of Polyethylene Blends,“
Pgm. Eng. Sci. 21, 12 (1981), pp. 869-872

18. Siegmann, A. and Nir, Y., “Structure - Property Relationships in Blends of Linear Low- and
Conventional Low-Density Polyethylene as Blown Films,“ Pam. Eng. Sci. 27, 15 (1987),
pp. 1182-1186

19. Utracki, L A. and Schiund, 6., “Linear Low Density Polyethylenes and Their Blends: Part 4 Shear
Flow of LLDPE Blends with LLDPE and LDPE," ngm. Eng. Sci. 27, 20 (1987),
pp. 1512-1522

APPENDIX A

Analysis of Variance of The Mechanical Properties of LDPE/LLDPE Blend

Table 13: Analysis of Variance Table at 95% Confidence Level for Forces to Cause Seal

Failure

 

Source of Degree of Sum of Mean F-vaiues Prob.
Variation Freedom Squares

 

Between 4 0.445 1.114 10.245 0.000
Within 45 4.892 0.109

 

Total 49 9.346

Table 14: Analysis of Variance Table at 95% Confidence Level for Tensile Strength at

Break (Machine Direction)

 

Source of Degree of Sum of Mean F-vaiues Prob.
Variation Freedom Squares

 

Between 4 35734231 8933558 7.421 0.0001
Within 45 54168896 1203753

 

Total 49 89%3129

Table 15: Analysis of Variance Table at 95% Confidence Level for Tensile Strength at

Yield (Cross Direction)

 

Source of Degree of Sum of Mean F-values Prob.
Variation Freedom Squares

 

Between 4 3653503 91337.6 1.197 0.3251
Within 45 34332323 76294.1

 

Total 49 37%5826

57

58
Table 16: Analysis of Variance Table at 95% Confidence Level for Modulus of Elasticity

(Machine Direction)

 

Source of Degree of Sum of Mean F-values Prob.
Variation Freedom Squares

 

Between 4 19890.3 4972.6 1.184 0.331
Within 45 188911.? 4198.04

 

Total 49 2088021

Table 17: Analysis of Variance Table at 95% Confidence Level for Modulus of Elasticity

(Cross Direction)

 

Source of Degree of Sum of Mean F-vaiues Prob.
Variation Freedom Squares

 

Between 4 200676690 50169172 2.038 0.105
Within 45 1 107591869 24613153

 

Total 49 1308268558

Table 18: Analysis of Variance Table at 95% Confidence Level for % Elongation at
Break (Machine Direction)

 

Sourceof Degreeof Sumof Mean F-vaiues Prob.
Variation Freedom Squares

 

Between 4 1846263 46156.6 13.644 0.000
Within 45 1522285 3382.9

 

Total 49 3368548

59
Table 19: Analysis of Variance Table at 95% Confidence Level for % Elongation at

.Yield (Cross Direction)

 

Source of Degree of Sum of Mean F-vaiues Prob.
Variation Freedom Squares

 

Between 4 16164.9 4041.2 1.761 0.1534
Within 45 1032522 2294.5

 

Total 49 119417.1

Table 20: Analysis of Variance Table at 95% Confidence Level for Tear Resistance Test

(Machine Direction)

 

Source of Degree of Sum of Mean F-values Prob.
Variation Freedom Squares

 

 

Between 4 181618453 45404613 37.6 0.0000
Within 45 54360675 120801 .5
Total 49 235979129

Table 21: Analysis of Variance Table at 95% Confidence Level for Tear Resistance Test

(Cross Direction)

 

Source of Degree of Sum of Mean F-values Prob.
Variation Freedom Squares

 

Between 4 40699874.?10174968.7 10.9 0.0000
Wlhin 45 417508405 9277965

 

Total 49 824507152

APPENDIX B

 

Calculations of Mechanical Properties

Calculation of Tensile Properties

1. Tensile Strength: the maximum tensile stress sustained by the specimen during a tension test.

Tensile Strength = Maximum lcgc
Minimum Cross Section Area

2. %Elongation: the increase in length produced in the gage length of the test specimen by a tensile

load

%Elongation = §x_tcn§icn
Original Gauge Length

3. Proportional Limit: the greatest stress which a material is caable of sustaining without any
deviation from proportionality of stress to strain (hooke’s law. ‘

4. Modulus of Elasticity: the ratio of stress to corresponding strain below the proportional limit of
a material. .

Modulus of Elasticity = Syccc
Strain

Stress -"

 

 

Strain

Figure 19: Normal Stress and Strain Curve

60

61
Calculation of impact Failure Weight
w, = wo + [ W(A/N - 1 /2)]
where W, is an impact failure weight
rii Is the total number of X's at each missile weight
i is 0 to n where 0 is for the lowest missile weight at which nl value has been entered
A is the product of inl
W0 Is a missile weight to which an nI value zero is assigned
oW is the uniform missile weight employed

N is total number of failures

Calculation of Tearing force

Average tearing force. of. = W
number of piles

 

APPENDIX C

 

Table 22: Load and Extension Obtained from Seal Strength Test of Sample No. 1

Raw Data

 

 

Replication Load Extension Type of Failure
(lbs) (in.)
1 3.1 19 5.868 delamlnation
2 2.679 5.412 delamlnation
3 3.925 12.800 break at seal
4 2.556 3.500 delamlnation
5 3.162 7.339 break at seal
6 2.642 4.886 break at seal
7 2.405 4.005 break at seal
8 3.173 9.176 break at seal
9 2.776 6.651 break at seal
10 2.561 5.774 break at seal

 

Table 23: Load and Extension Obtained from Seal Strength Test of Sample No. 2

 

 

Replication Load Extension Type of Failure
(lbs) (in)
1 2.545 4.191 delamlnation
2 3.248 9.985 break at seal
3 2.774 6.932 break at seal
4 3.189 10.330 break at seal
5 3.039 9.192 break at seal
6 2.330 3.030 delamlnation
7 2.459 5.012 break at seal
8 2.878 6.818 break at seal
9 2.985 8.221 break at seal
10 2.706 7.318 break at seal

 

 

63
Table 24: Load and Extension Obtained from Seal Strength Test of Sample No.

 

 

Replication Load Extension Type of Failure
(lbs) (in.)

1 3.495 14.120 break at seal
2 3.098 12.050 break at seal
3 3.425 12.500 break at seal
4 3.323 12.040 break at seal
5 2.663 9.972 break at seal
6 2.421 4.316 delamination
7 2.507 7.918 break at seal
8 2.642 10.240 break at seal
9 3.184 11.990 break at seal
10 3.039 11.380 break at seal

 

Table 25: Load and Extension Obtained from Seal Strength Test of Sample No. 4

 

Extension

 

Replication Load Type of Failure
(lbs.) (in.)
1 2.298 10.500 break at seal
2 2.089 5.521 delamination
3 2.507 9.355 break at seal
4 2.250 9.387 break at seal
5 2.454 9.994 break at seal
6 2.352 7.877 break at seal
7 2.475 10.220 break at seal
8 2.368 6.334 break at seal
9 1.976 5.295 break at seal
10 2.260 7.634 break at seal

 

64

Table 26: Load and Extension Obtained from Seal Strength Test of Sample No. 5

 

 

Replication Load Extension Type of Failure
(lbs) (in.)

1 2.110 9.624 break at seal
2 2.846 11.680 break at seal
3 2.341 7.544 break at seal
4 2.250 10.700 break at seal
5 2.405 10.540 break at seal
6 2.174 9.534 break at seal
7 2.196 10.060 break at seal
8 2.309 10.700 break at seal
9 2.266 10.520 break at seal
10 2.153 10.200 break at seal

 

 

Table 27: Load and Extension Obtained from Tensile Properties Test of Sample No.1

(Machine Direction)

 

Replication Load Extension Type of Failure

 

(lbs-l

1 4.225 14.23 break at upper law
2 4.011 14.11 break at lower jaw
3 3.715 13.35 break at upper law
4 4.113 13.60 break at upper jaw
5 3.318 9.756 break at middle law
6 3.871 13.12 break at lower law
7 3.248 11.18 break at upper jaw
8 3.898 12.89 break at upper law
9 3.060 9.38 break at lower jaw
10 3.071 9.51 break at lower jaw

 

 

65
Table 28: Load and Extension Obtained from Tensile Properties Test of Sample No.1

(Cross Direction)

 

Replication Load Extension Type of Failure

 

(lbs) (in.)

1 3.447 20.63 break at upper jaw
2 3.334 20.02 break at upper jaw
3 3.216 19.53 break at lower jaw
4 3.173 19.58 break at lower jaw
5 3.404 20.11 break at upper jaw
6 2.985 19.86 break at lower jaw
7 2.862 19.54 break at lower jaw
8 2.695 18.46 break at lower jaw
9 3.093 20.04 break at upper jaw
10 3.039 19.95 break at upper jaw

 

Table 29: Load and Extension Obtained from Tensile Properties Test of Sample No.2

(Machine direction)

 

Replcstion Load Extension Type of Failure

 

(lbs) (in.)
1 4.182 14.90 break at upper jaw
2 5.170 15.49 break at lower jaw
3 4.059 14.50 break at upper jaw
4 4.213 14.66 break at upper jaw
5 3.737 13.27 break at upper jaw
6 3.946 14.17 break at upper jaw
7 3.893 13.21 break at upper jaw
8 4.016 14.38 break at upper jaw
9 3.474 12.89 break at upper jaw
10 3.876 14.00 break at upper jaw

 

 

66
Table 30: Load and Extension Obtained from Tensile Properties Test of Sample No.2 (Cross

Direction)

 

Replication Load Extension Type of Failure

 

(lbs.) (in.)

1 2.706 17.13 break at lower jaw
2 3.157 18.91 break at upper jaw
3 3.662 20.59 break at upper jaw
4 3.544 20.10 break at upper jaw
5 2.787 17.86 break at upper jaw
6 2.819 18.79 break at lower jaw
7 3.119 19.75 break at upper jaw
8 2.921 18.55 break at lower jaw
9 2.668 17.78 break at lower jaw
10 3.544 20.02 break at upper jaw

 

 

Table 31: Load and Extension Obtained from Tensile Properties Test of Sample No.3 1

 

 

(Machine Direction)
Replication Load Extension Type of Failure
(lbs) (in-)
1 3.721 13.66 break at lower jaw
2 4.424 14.78 break at upper jaw
3 4.166 15.17 break at upper jaw
4 5.219 15.72 break at upper jaw
5 5.177 16.38 break at upper jaw
6 4.703 14.45 break at upper jaw
7 4.682 14.75 break at lower jaw
8 4.166 14.69 break at lower jaw
9 4.644 15.19 break at upper jaw
10 4.440 15.37 break at lower jaw

 

 

67
Table 32: Load and Extension Obtained from Tensil Properties Test of Sample No.3 (Ccross

 

 

Direction)
Replication Load Extension Type of Failure
(lbs) (in.)

1 3.758 20.48 break at lower jaw
2 3.383 20.04 break at upper jaw
3 3.302 20.18 break at lower jaw
4 3.168 19.25 break at upper jaw
5 2.894 18.05 break at lower jaw
6 3.801 20.11 break at upper jaw
7 3.297 19.53 break at lower jaw
8 3.699 20.14 break at lower jaw
9 3.447 19.24 break at lower jaw
10 3.468 19.73 break at upper jaw

 

 

Table 33: Load and Extension Obtained from Tensile Properties Test of Sample No.4

(Machine Direction)

 

Replication Load Extension Type of Failure

 

(lbs.) (in.)
1 4.381 15.63 break at upper jaw
2 5.638 16.49 break at lower law
3 4.478 14.93 break at upper jaw
4 4.795 16.38 break at upper jaw
5 4.344 13.82 break at lower jaw
6 4.413 15.26 break at lower jaw
7 5.068 15.99 break at lower jaw
8 5.154 15.58 break at lower jaw
9 3.565 1.374 break at upper jaw
10 4.199 15.00 breakat lower jaw

 

 

68
Table 34: Load and Extension Obtained from Tensfle Properties Test of Sample No.4 (Cross
Direction)

 

Replication Load Extension Type of Failure

 

(lbs) (in.)

1 3.301 20.27 break at lower jaw
2 4.054 20.47 break at lower jaw
3 3.066 18.77 break at lower law
4 3.624 19.11 break at lower jaw
5 3.318 18.66 break at upper jaw
6 3.007 18.37 break at upper jaw
7 3.817 20.68 break at lower jaw
8 2.647 16.25 break at lower jaw
9 3.205 19.08 break at lower jaw
10 3.195 19.15 break at upper jaw

 

Table 35: Load and Extension Obtained from Tensile Properties Test of Sample No. 5

(Mmachine Direction)

 

Replication Load Extension Type of Failure

 

(lbs) (in.)

1 5.638 16.10 break at lower jaw
2 4.027 15.25 break at upper jaw
3 3.961 14.42 break at upper jaw
4 4.923 16.72 break at upper jaw
5 4.698 15.76 break at lower jaw
6 4.800 15.40 break at upper jaw
7 4.521 15.26 break at lower jaw
8 5.326 16.19 break at upper jaw
9 3.726 13.92 break at upper jaw
10 3.887 14.48 break at upper jaw

 

69
Table 36: Load and Extension Obtained from Tensile Properties Test of Sample No.5

(Ccross Direction)

 

 

Replication Load Extension Type of Failure
(lbs.) (in.)

1 3.227 17.99 break at upper jaw
2 3.447 18.70 break at lower jaw
3 4.321 20.28 break at lower jaw
4 3.834 19.55 break at lower jaw
5 3.603 19.47 break at upper jaw
6 3.640 19.21 break at lower jaw
7 3.699 19.00 break at lower jaw
8 3.424 18.53 break at upper jaw
9 3.522 19.75 break at lower jaw
10 3.039 17.19 break at upper jaw

 

Table 37: Scale Reading Value from A Tear Resistance Test of Sample no. 1

 

Replication

 

@V010180M-e

‘

O“)

Scale reading value
machine direction cross direction

3.5 49.5

6.0 49.5
8.5 40.5
6.0 39.5
6.0 39.5
3.5 38.6
4.0 46.5
6.0 44.0
10.0 48.0
5.0 50.5

 

70
Table 38: Scale Reading Value from A Tear Resistance Test of Sample No. 2

 

 

Replication Scale reading value
machine direction cross direction
1 4.5 58.5
2 5.0 63.0
3 7.0 58.0
4 6.0 56.5
5 6.5 42.0
6 7.0 46.0
7 5.5 53.5
8 8.9 50.0
9 4.0 59.5
10 4.0 54.0

 

Table 39: Scale Reading Value from A Tear Resistance Test of Sample No. 3

 

 

Replication Scale reading value
machine direction cross direction
1 7.0 54.0
2 9.0 54.0
3 7.5 67.0
4 6.5 75.5
5 10.5 53.5
6 7.5 49.0
7 7.5 64.0
8 8.5 71.0
9 7.0 65.5
10 7.0 56.0

 

71
Table 40: Scale Reading Value from A Tear Resistance Test of Sample No. 4

 

 

Replication Scale reading value
machine direction cross direction
1 16.0 59.0
2 12.0 63.5
3 8.5 54.0
4 13.5 54.0
5 13.5 61.5
6 . 9.0 68.0
7 14.0 59.5
8 11.0 65.5
9 13.5 53.0
10 14.5 54.0

 

Table 41: Scale Reading Value from A Tear Resistance Test of Sample No. 5

 

 

Replication Scale reading value
machine direction cross direction
1 18.0 53.0
2 10.5 57.0
3 15.5 53.5
4 14.0 52.0
5 16.0 62.5
6 21.5 64.0
7 17.5 56.0
8 16.0 65.0
9 11.5 61.5
10 13.5 59.0

 

72
Table 42: The Result Fem impact Resistance

 

Sample no. N A W

0

w w,

 

10 2 63.76 15 59.26
10 14 63.76 15 77.26
10 16 63.76 15 80.26
10 12 108.76 15 119.26
10 12 108.76 15 119.26

(”ham-4

 

Table 43: Calculated Tensile Properties Values from Tensile Properties Tests (Machine

Direction)

 

Sample Replication Tensile %Elongatlon ModiJus of

 

no. Strength elasticity
(psi)
1 1 4225.0 71 1.1 13333
1 2 401 1.0 705.5 20000
1 3 4127.8 667.5 14583
1 4 3808.3 680.0 20000
1 5 3160.3 487.8 23000
1 6 3910.1 656.0 15000
1 7 3608.9 559.0 16667
1 8 3859.4 644.5 22500
1 9 3326.1 468.9 17500
1 10 3412.2 475.7 15000
2 1 3801.8 745.0 20000
2 2 4535.1 774.5 20000
2 3 4018.8 725.0 . 20000
2 4 40&.1 733.0 26667
2 5 3628.2 663.5 20000
2 6 4026.5 708.5 17500
2 7 3707.6 660.5 21000
2 8 4462.2 719.0 19500
2 9 3903.4 644.5 16000
2 10 4259.3 700.0 16500
3 1 4044.6 683.0 13333
3 2 4253.9 738.0 20000
3 3 4124.8 785.5 25000
3 4 4349.2 786.0 25000
3 5 4968.0 819.0 17500
3 6 3964.3 768.5 17500
3 7 4036.2 737.5 20000
3 8 4479.6 734.5 16000
3 9 4300.0 759.5 25000
3 10 4703.0 722.5 25000

 

73
Table 43: (Cont’d)

 

Sample Replication Tensile %Elongation Modulus of

 

no. Strength elasticity
(psi)
4 1 4867.8 781 .5 12500
4 2 4860.4 824.5 21000
4 3 4390.2 746.5 14000
4 4 4447.5 819.0 15000
4 5 4344.0 691.0 23333
4 6 4369.3 763.0 19500
4 7 4862.7 799.5 20000
4 8 4295.0 779.0 25000
4 9 3961.1 687.0 13500
4 10 4665.6 750.0 14000
5 1 5125.5 805.1 13333
5 2 3909.7 762.6 18000
5 3 3883.3 721.1 16500
5 4 4558.3 836.1 1 1250
5 5 4474.3 778.1 1 1667
5 6 4247.8 770.0 17500
5 7 4521.0 763.0 12500
5 8 4787.4 809.5 18500
5 9 3802.0 &6.0 20000
5 10 4007.2 724.0 23000

 

Table 44: Calculated Tensile Properties Values from Tensile Properties Tests (Cross

Direction)

 

Sample Replication Tensle %Elongaton Moddus of

 

no. Strength elasticity
(psi)
1 1 3162.4 1031.3 20000
1 2 3030.9 1001.0 22875
1 3 3005.6 976.5 25000
1 4 2911.0 976.0 40000
1 5 3066.7 1005.5 35000
1 6 3021.6 977.0 17500
1 7 2722.2 923.0 16500
1 8 3172.3 1002.0 25000
1 9 2979.4 997.5 17500
1 10 2926.5 993.0 25000

 

74
Table 44: (Cont’d)

 

Sample Replication Tensile %Elongaton Modulus of

 

no. Strength elasticity
(psi)

2 1 2529.0 856.5 16000
2 2 2870.0 945.5 23333
2 3 3555.3 1029.5 20000
2 4 3136.3 1005.0 30000
2 5 2732.4 &3.0 30000
2 6 3031.2 939.5 17000
2 7 3088.1 987.5 19000
2 8 3042.7 927.5 19000
2 9 2808.4 889.0 19000
2 10 3343.4 1001.0 21000
3 1 3447.7 1024.0 20000
3 2 3161.7 1002.0 20000
3 3 3205.8 1009.0 25000
3 4 3046.2 962.5 20000
3 5 2809.7 902.5 21053
3 6 31 10.4 976.5 21000
3 7 3362.7 1007.7 20000
3 8 31 13.6 962.0 25000
3 9 321 1.0 986.5 32000
3 10 3334.2 1005.5 25000
4 1 3519.4 1013.5 15667
4 2 3652.3 1023.5 23500
4 3 3227.4 938.5 16500
4 4 3179.0 955.5 15000
4 5 3044.0 933.0 13333
4 6 3068.4 918.5 18500
4 7 3470.0 1034.0 22500
4 8 2406.4 812.5 19000
4 9 3052.4 954.0 19000
4 10 3227.3 957.5 21000
5 1 2734.8 899.5 19500
5 2 3379.0 935.0 21000
5 3 3858.0 1014.0 18500
5 4 3363.2 977.5 18000
5 5 3160.5 973.5 19000
5 6 3339.5 960.5 23000
5 7 2802.3 950.0 20000
5 8 31 12.7 926.5 30000
5 9 3291.6 984.5 24000
5 10 2737.84 859.5 20000

 

 

“11111111111111“