NOVEL SYNTHETIC ROUTE TO BIOBASED SILYLATED SOYBEAN OIL FOR
USE AS COATING MATERIAL
By
Yue Zhuang

A THESIS
Submitted to
Michigan State University
in partial fulfillment of the requirements for the degree of
MASTER OF SCIENCE
Chemical Engineering
2011

ABSTRACT
NOVEL SYNTHETIC ROUTE TO BIOBASED SILYLATED SOYBEAN OIL FOR
USE AS COATING MATERIAL
By
Yue Zhuang
Bio-based materials synthesized from sustainable and renewable resources are
gaining considerable attention in academe and industry. Soybean oil is a bio
renewable molecule suitable for conversion to useful materials. It possesses
unsaturated (double bond) structure in its molecular chain, and can be modified or
reacted with other reactive chemical species to produce value added biobased
materials.
Coating materials prepared from the reaction of soybean oil and reactive silanes
(vinyl trimethoxy silane and vinyl terminated polydimethylsiloxane) are described in
this thesis. The silylation reaction occurs at high temperature and pressure in the
presence of peroxide as catalyst. The silane molecule was grafted onto soybean oil
backbone and on curing with water gave coating materials with water resistant
property. Biobased products containing different molar ratios of soybean oil and
silane were synthesized and characterized. The silylated soybean oil was coated on the
substances and the coating performances evaluated. These coating materials were
evaluated for biodegradability and showed that they were biodegradable under
aqueous conditions. Biodegradability of these coating materials was also measured to
demonstrate that these materials were biodegradable
These coating materials are recommended as protective coatings for water
sensitive substances, such as wood, paper and starch foams.

DEDICATION
This thesis is dedicated to my family in China

iii

ACKNOWLEGEMENTS

I would like to express my sincere gratitude to my advisor Dr. Ramani Narayan,
for giving me this great opportunity to work on this project, and for his patience and
support on this work. Thanks to Dr. Daniel Graiver for his continuous help, advice
and support on my research. Thanks to Ken Farminer for his encouragement and
suggestions during my master’s study. Thanks to Dr. Laurent Matuana for serving on
my committee and for reviewing my master thesis.
I am grateful for all the understanding and support from my family in China. I
also want to thank all the friends and colleagues in BMRG research group for their
help and encouragements during my research. Thank Kelby Thayer for training me on
the analytical equipment in the School of Packaging and allowing me to use their
testing equipment. Thanks to Dr. Daniel Holmes for the training and continuous help
with the NMR.

iv

TABLE OF CONTENTS
LIST OF TABLES ....................................................................................................................... VIII
LIST OF FIGURES ....................................................................................................................... IX

CHAPTER 1: INTRODUCTION AND BACKGROUND............................................... 1
1.1 INTRODUCTION ..................................................................................................................... 1
1.1.1 OBJECTIVES........................................................................................................ 1
1.1.2 ORGANIZATION OF THIS THESIS ......................................................................... 2
1.2 BACKGROUND ........................................................................................................................ 3
1.2.1 SOYBEAN OIL ..................................................................................................... 3
1.2.2 REACTIVE SILANES AND SILICONES .................................................................... 4
1.2.3 COATING ............................................................................................................ 6
1.2.3.1 Anticorrosive Coatings .............................................................................. 6
1.2.3.2 Waterproof Coatings .................................................................................. 7
1.2.4 COATING PROCEDURE ........................................................................................ 8
1.2.4.1 Surface Activation ...................................................................................... 8
1.2.4.2 Coating ....................................................................................................... 8
1.2.4.3 Curing ........................................................................................................ 8
REFERENCES................................................................................................................................... 9
CHAPTER 2: SYNTHESIS SILYLATED SOYBEAN OIL PRODUCT AND
COMPONENT ANALYSIS........................................................................................................ 11
2.1 INTRODUCTION ................................................................................................................... 11
2.2 EXPERIMENTAL .................................................................................................................. 13
2.2.1 MATERIALS ...................................................................................................... 13
2.2.2 SYNTHESIS OF SILYLATED SOYBEAN OIL .......................................................... 13
2.2.3 PURIFICATION OF SILYLATED SOYBEAN OIL PRODUCTS .................................... 14
2.2.4 IODINE VALUE OF SILYLATED SOYBEAN OIL PRODUCTS .................................... 15
2.2.5 TGA................................................................................................................. 15
2.2.6 FTIR ................................................................................................................ 16
2.2.7 NMR ................................................................................................................ 16
2.2.8 MOLECULAR WEIGHT MEASUREMENT .............................................................. 16
2.3 RESULTS AND DISSCUSSION ....................................................................................... 17
2.3.1 MECHANISM OF SILYLATED REACTION ............................................................. 17
2.3.2 IODINE VALUES OF REACTANTS AND DIFFERENT REACTION PRODUCTS ............ 19
2.3.3 MASS BALANCE AND REACTION CONVERSION OF SILYLATED REACTION .......... 21
2.3.4 TGA RESULTS OF SILYLATED SOYBEAN OIL PRODUCTS .................................... 21
2.3.5 FTIR RESULTS OF SILYLATED SOYBEAN OIL PRODUCTS ................................... 24
v

2.3.6 NMR RESULTS OF SILYLATED SOYBEAN OIL PRODUCTS ................................... 27
2.3.7 MOLECULAR WEIGHT RESULTS OF SILYLATED SOYBEAN OIL PRODUCTS .......... 30
REFERENCES................................................................................................................................. 32
CHAPTER 3: COATING PERFORMANCE ANALYSIS ........................................... 34
3.1 INTRODUCTION ................................................................................................................... 34
3.2 DIFFERENT COATING SYSTEMS OF PAPER COATING ............................. 35
3.3 COATING PROCEDURE AND CURING CONDITIONS FOR PANEL
COATING .......................................................................................................................................... 37
3.3.1 PRETREATMENT OF STEEL PANELS ................................................................... 37
3.3.2 COATING .......................................................................................................... 37
3.3.3 CURING ............................................................................................................ 37
3.4 PROPERTY CHARACTERIZATION .......................................................................... 38
3.4.1 WATER VAPOR TRANSMISSION RATE MEASUREMENT ..................................... 38
3.4.1.1 Literature review ...................................................................................... 38
3.4.1.2 Method ..................................................................................................... 39
3.4.2 WATER CONTACT ANGLE MEASUREMENT......................................................... 40
3.4.2.1 Literature review ...................................................................................... 41
3.4.2.2 Method ..................................................................................................... 42
3.4.3 COBB TEST ....................................................................................................... 42
3.4.3.1 Method ..................................................................................................... 43
3.4.4 BIODEGRADABILITY TEST................................................................................. 43
3.4.4.1 Literature review ...................................................................................... 44
3.4.4.2 Method ..................................................................................................... 45
3.5 RESULTS AND DISCUSSION.......................................................................................... 46
3.5.1 COATING PERFORMANCES ................................................................................ 46
3.5.2 WVTR RESULTS .............................................................................................. 48
3.5.3 WATER CONTACT ANGLE RESULTS ................................................................... 50
3.5.4 COBB TEST RESULTS ......................................................................................... 52
3.5.5 BIODEGRADABILITY TEST RESULTS .................................................................. 54
REFERENCES................................................................................................................................. 57
CHAPTER 4: ALTERNATIVE REACTANTS TO SYNTHESIZE COATING
MATERIAL ...................................................................................................................................... 59
4.1 SYNTHESIS OF METHYL OLEATE AND VINYL TRIMETHOXY
SILANE ADDUCT ......................................................................................................................... 59
4.1.1 EXPERIMENTAL ................................................................................................ 61
4.1.1.1 Materials .................................................................................................. 61
4.1.1.2 Synthesis of methyl oleate and vinyl trimethoxy silane adduct ................ 61
4.1.2 CHARACTERIZATION ........................................................................................ 62
4.1.3 RESULTS AND DISCUSSION ............................................................................... 62
vi

4.1.3.1 Gravimetric determination and conversion calculation .......................... 62
4.1.3.2 Iodine values ............................................................................................ 63
4.2 SYNTHESIS OF EPOXIDIZED SOYBEAN OIL AND AMINO SILANE
ADDUCT ............................................................................................................................................ 65
4.2.1 EXPERIMENTAL ................................................................................................ 66
4.2.1.1 Materials .................................................................................................. 66
4.2.1.2 Synthesis of epoxidized soybean oil and NH2(CH2)3Si(OEt)3 adduct ...... 66
4.2.1.3 Coating application with silylated epoxidized soybean oil...................... 66
4.2.2 CHARATERIZATION .......................................................................................... 67
4.2.2.1 FTIR ......................................................................................................... 67
4.2.2.2 TGA .......................................................................................................... 67
4.2.3 RESULTS AND DISCUSSION ............................................................................... 68
4.2.3.1 FTIR results of silylated epoxidized soybean oil product ........................ 68
4.2.3.2 TGA results of silylated epoxidized soybean oil product ......................... 69
4.2.3.3 Coating performance ............................................................................... 71
REFERENCES................................................................................................................................. 73
CHAPTER 5: CONCLUSIONS ................................................................................................ 75
5.1 CONCLUSIONS....................................................................................................................... 75
5.2 RECOMMENDATIONS ...................................................................................................... 75

vii

LIST OF TABLES
Table 1 Iodine values of original reactants and silylated products .............................. 20
Table 2 Mass balances and grafting percentages of 1:7, 1:3 and 1:2:1 silylation
reactions ......................................................................................................... 21
Table 3 Calculation table of grafting percentage of 1:3 oil product from TGA data .. 23
Table 4 Average molecular weights and PDI of 1:3 oil product and pure soybean oil30
Table 5 Paper coating samples information ................................................................. 47
Table 6 WVTR results of coating samples made from 1:3 oil product with different
coating thickness ......................................................................................... 48
Table 7 WVTR results of coating samples made from 1:2:1 oil product with different
coating systems ............................................................................................ 49
Table 8 Water contact angle of 1 mil paper coatings with different coating systems . 51
Table 9 Cobb test results of 1 mil paper coatings with different coating systems....... 53
Table 10 Mass balances and grafting percentages of 1:5 silylation reaction at different
reaction temperature .................................................................................... 63
Table 11 Iodine values of silylated oil products, pure methyl oleate and pure VTMOS
..................................................................................................................... 64
Table 12 Calculation table of grafting percentage of the reaction between epoxidized
soybean oil and amino silane ....................................................................... 71

viii

LIST OF FIGURES
Figure 1 Five Major Fatty Acid Components in Soybean Oil ....................................... 4
Figure 2 Silane basic chemical formula ......................................................................... 5
Figure 3 Structure of Polydimethylsiloxane .................................................................. 5
Figure 4 Scheme of the head part of Parr Reactor ....................................................... 12
Figure 5 Alder - ENE reaction pathway between VTMOS and soybean oil ............... 18
Figure 6 Diels - Alder reaction pathway between VTMOS and soybean oil .............. 18
Figure 7 Peroxide mediated grafting pathway between VTMOS and soybean oil...... 19
Figure 8 Pure soybean oil TGA weight loss plot ......................................................... 22
Figure 9 1:3 molar ratio oil product TGA weight loss plot ......................................... 22
Figure 10 1:3 molar ratio oil product TGA derivative plot ......................................... 23
Figure 11 FTIR spectrum for comparison of original reactants and final oil product . 24
Figure 12 Comparison of FTIR spectrum for original reactants and final oil product
-1
around 800 cm ........................................................................................ 25
Figure 13 Comparison of FTIR spectrum for all samples taken during reaction ........ 26
Figure 14 Peak area changes of samples in FTIR v.s. reaction time ........................... 27
Figure 15 1H-NMR spectrum of pure soybean oil with peak assignments .................. 28
Figure 16 1H-NMR spectrum of 1:3 oil product with integration ............................... 29
Figure 17 13C-NMR spectrum of 1:3 oil product ......................................................... 30
Figure 18 Scheme of the interfacial tensions and water contact angle of a water
droplet ....................................................................................................... 41
Figure 19 1:7 silylated soybean oil product film biodegradability plot ....................... 55
Figure 20 1:3 silylated soybean oil product film biodegradability plot ....................... 55
Figure 21 1:2:1 silylated soybean oil product film and pure VTMOS film
biodegradability plot ................................................................................. 56
Figure 22 Methyl Oleate molecular structure .............................................................. 59
ix

Figure 23 FTIR spectrum of epoxidized soybean oil (green line) and oil product after
reaction (red line) ...................................................................................... 68
Figure 24 Expanded FTIR spectrum of epoxidized soybean oil (green line) and oil
product after reaction (red line) ................................................................ 69
Figure 25 Pure epoxidized soybean oil TGA weight loss and derivative plot............. 70
Figure 26 Silylated epoxidized soybean oil product TGA weight loss and derivative
plot ............................................................................................................ 70

x

Chapter 1: Introduction and background
1.1 Introduction
Carbon is the major basic element in the world, from which organic materials
and some inorganic materials are derived. How to sustain these products in the abuse
of petroleum based products and maintain environment status becomes a major issue.
Nowadays, many scientists and engineers are focused on bio-based materials
which have almost the same function as petroleum based products but can be fully
degraded by the environment itself. Soybean oil is one of these bio-based materials,
and this kind of material is widely planted all over the world, thus providing a
sustainable source of raw materials as reactants for biocomposites. By using this
bio-based material, researchers want to produce new materials which can replace
petroleum based products with almost the same function and help to reduce global
warming issues. Moreover, soybean oil, which is extracted from soybean seeds, can
be easily biodegraded in the environment. [1]
By adding functional groups or reactive groups, soybean oil can be used to
synthesize biocomposites in many fields. These biocomposites made from vegetable
oil have been used in alkyd resin formulations, especially for coating applications. [2]

1.1.1 Objectives
In this project, oil-based coatings are prepared by reacting unsaturated soybean
oil with reactive silane. This reaction occurs at high temperature and high pressure
conditions, and finally silane is grafted onto the soybean oil chain to provide coating

1

and curing, and the soybean oil will also provide a water resistant property to this oil
product. There are three main objectives in this project that have been studied.
(1) Reaction scheme between soybean oil and reactive silane; this can help us
to control the products properties and improve reaction conversion. It can be studied
by using different reaction molar ratios, reaction times and reactants.
(2) Performance of different coating systems on coating appearance and water
resistant property. There are many methods of paper coating and different additives
could be added into the coating material to provide multiple functions. Which is the
best to provide adhesion and water resistant property will be our aim in this project.
(3) Biodegradability of this coating material. As has been stated, this project is
based on soybean oil, which is a renewable resource and environmentally friendly,
and thus “green”. Successful completion of this work should lead to a new bio-based
and biodegradable coating material with water resistant property and will also help to
better understand the mechanism of reaction between soybean oil and reactive silanes.

1.1.2 Organization of this Thesis
The thesis is divided into five main parts. In Chapter 1, the need for new
bio-based coating material is addressed. This chapter also includes comprehensive
reviews and background information of current problems as well as current research
activities in this field.
In Chapter 2, detailed experimental procedures are given including the
synthesis of these novel oil-phase coating materials, which can be later applied to

2

different coating systems for paper coating. This chapter also includes detailed
structural analyses of the products using FT-IR, NMR, and other chemical methods.
In Chapter 3, different coating systems and coating procedures are described.
Water resistant property and biodegradability tests investigated include water vapor
transmission test, water contact angle, Cobb test, and biodegradable test.
In Chapter 4, the focus is on alternative reactants to substitute soybean oil or
reactive silane to synthesize coating material with water resistant property.
Chapter 5 draws conclusions based on the finished work and suggests future
research plans.

1.2 Background
The fact that bio-based coating material is an important and active research
topic has attracted many researchers into this field. In order to further understand this
topic, in this section, soybean oil, reactive silane, coating system and normal coating
procedure are discussed.

1.2.1 Soybean oil
Soybean oil is a widely-used annually renewable vegetable oil. The main
structure of soybean oil is triglyceride, and five main triglycerides in soybean oil are
consist of saturated and unsaturated long chain fatty acids, which is shown in Figure
1. [1]

3

Alpha-Linolenic Acid --- 7%

Stearic Acid --- 4%

Linoleic Acid --- 51%

Palmitic Acid --- 10%

Oleic Acid --- 23%
Figure 1 Five Major Fatty Acid Components in Soybean Oil
In the United States, soybean oil is easily obtained and is relatively
inexpensive, which makes it a great resource for bio-synthesis. But raw soybean oil is
not a good coating material, because it dries very slowly and has poor coating quality.
After reacting with other chemicals at the double bonds, the reactive soybean oil can
be expected to yield more flexible and better color retention composite coating
materials, which meet the requirements of the coating. [3]

1.2.2 Reactive Silanes and Silicones
Both silanes and silicones are silicon-based chemicals, which mean that there
is at least one silicon atom in its structure. Silicon atom, which is in the same column
of carbon atom in the periodic table, can be attached four other atoms to make
molecules that are structurally similar to carbon-based chemicals. [4]
Reactive silanes. Silanes are silicon-based monomers that are similar to
alkynes. A basic silane has the following structure:

4

Figure 2 Silane basic chemical formula

in which R1, R2, R3 and R4 can be substituted by any chemical groups or
atoms.
Reactive silanes, especially vinyl silanes (-Si-CH=CH2) and silicon hydrides
(-Si-H), can be reacted with other functional groups to produce useful materials. [5]
Silicones. Silicones are polymers with the repeat unit of silicon and oxygen
atoms in the main polymer chain and other chemical elements in its structure. They
are man-made compounds with a wide variety of forms, and the most common
organic silicone is polydimethylsiloxane (PDMS), as shown in Figure 3. [6]

Figure 3 Structure of Polydimethylsiloxane
Unlike most polymers prepared from monomers, PDMS cannot be simply
polymerized from a silicone group with a double bond between oxygen and silicon,
for in nature, it is common to see the silicon atom attached by a single bond with two
oxygen atoms, rather than a double bond to a single atom. To obtain PDMS, people

5

may use dimethyldichlorosilane to react with water as follows: [7]
n Si(CH3)2Cl2 + n H2O → [Si(CH3)2O]n + 2n HCl
PDMS can be used to prepare water-repellent coating materials which can later
be used as waterproofing applications. Zimmermann [8] group recently synthesized a
kind of superhydrophobic silicone coatings, which could be applied to many
substrates as waterproofing coatings. Moreover, this transparent coating material
showed antifouling and self-cleaning potentials as well as long-term stability in the
environment.
PDMS with functional end groups may have other useful applications. Vinyl
terminated PDMS can form a cross-linked structure during the reaction with a
multifunctional cross-linker. [9] If this cross-linked PDMS mixes with garnet, we can
prepare materials used in Light Emitting Diodes (LEDs). [10]

1.2.3 Coating
Coating is a protective layer of materials at the surface of a substrate. Coating
can help to improve corrosion resistance, wear resistance, wettability and other
properties of the surface, so this technique is widely applied in industry.

1.2.3.1 Anticorrosive Coatings
Corrosion is a common problem for all the substrates in modern society, because
it affects the appearance of this substrate; and can even cause serious damage of the
structure of the substrate, which leads to dramatic consequences. [11]

6

There are series of stimuli in the environment for corrosion, such as high
temperature, CO2 and acid solution. [12] These environmental elements lead to
different types of corrosion, which cannot be overcome by a single layer of coating.
Thus, anticorrosive coatings combine several different layers of coating material
together to achieve the best overall coating performance. These layers can be organic,
inorganic or metallic. Moreover, anticorrosive coatings should also have a good
adhesion to the coated substrate to ensure its durability.
Anticorrosive coatings usually consist of three parts, a primer, one or several
intermediate coats, and a topcoat. [13] The primer layer will prevent corrosion of the
surface and improve adhesion of the coating, and the intermediate layers can provide
sufficient thickness of the coating and isolate the invasion of the outside world. In
addition to provide gloss and required color, the top layer must have resistance to
radiation and different weather conditions.

1.2.3.2 Waterproof Coatings
Waterproof coatings, which have the property of high water repellence, are
potential surfaces for antifouling or self-cleaning products. [8] These coated surfaces
usually have the water contact angle larger than 150° and low surface energy. Silicone
or silane is usually an important component of these coatings.
Li [14] group recently fabricated superhydrophobic cellulose-based materials,
and this material can later be applied in textile industry and packaging field. A
solution-immersion process enables them to transform the normal hydrophilic group
on the cellulose into superhydrophobic ones. Hydrolyzed silane group Si-OH reacted

7

with the –OH group on the molecular chain of cellulose and formed a covalent bond.
This reaction condensed the siloxane polymer outside of the cellulose and became a
kind of coating with waterproof property.

1.2.4 Coating Procedure
1.2.4.1 Surface Activation
A surface activation step is commonly applied for cleaning or oxidization of
substrate surfaces to improve surface energy and facilitate bonding the coatings to the
substrate. More importantly, surface activation gives rise to reactive -OH functional
groups on the surface, which enhances the subsequent coating or grafting procedure.
[15]

1.2.4.2 Coating
Coating the substrate with coating materials. This step can be done by either
brushing or spraying required thickness of the coating materials.

1.2.4.3 Curing
During the cure step, the coatings cross-link to form a network of the coating
material and the surface becomes hard or tough. Curing conditions can affect the
quality of the coatings. Heat or chemical additives can be used to improve the cure.

8

REFERENCES

9

References
1. P. Tran, D. Graiver, and R. Narayan. Journal of Applied Polymer Science,
2006. 102(1): p. 69-75.
2. C.L. Yap, S. Gan, and H.K. Ng. Journal of Hazard Material, 2010. 177(1-3): p.
28-41.
3. G.H. Teng. Progress in Organic Coatings, 2001. 42(1-2): p. 29-37.
4. www.dowcorning.com/content/publishedlit/25-754-01.pdf
5. Dow Corning. https://www.xiameter.com/en/ExploreSilicones/Documents/
Silane%20Chemistry-1a-95-718-01-F2.pdf
6. D. Graiver, K.W. Farminer, and R. Narayan. Journal of Polymers and the
Environment, 2003. 11(4): p. 129-136.
7. http://en.wikipedia.org/wiki/Polydimethylsiloxane.
8. J. Zimmermann, G.R.J. Artus, and S. Seeger. Journal of Adhesion Science and
Technology, 2008. 22(3-4): p. 251-263.
9. V. Gevorgyan, L. Borisova, J. Popelis, E. Lukevics, Z. Foltynowicz. Journal
of Organometallic Chemistry, 1992. 424(1): p. 15-22.
10. A.C.C. Esteves, J. Brokken-Zijp, J. Laven, M. P. Van. Polymer, 2010. 51(1):
p. 136-145.
11. F. Fragata, R.P. Salai, C. Amorim, E. Almeida. Progress in Organic Coatings,
2006. 56(4): p. 257-268.
12. N.B. Dahotre, and S. Nayak. Surface & Coatings Technology, 2005. 194(1):
p. 58-67.
13. D. Kjernsmo, K. Kleven, J. Scheie, Corrosion Protection. 2003, Copenhagen:
Boarding A/S.
14. S.H. Li, S.B. Zhang, and X.H. Wang. Langmuir, 2008. 24(10): p. 5585-5590.
15. I. Wong, and C.M. Ho. Microfluidics and Nanofluidics, 2009. 7(3): p.
291-306.

10

Chapter 2: Synthesis silylated soybean oil product and component analysis
2.1 Introduction
Coating is a versatile and useful procedure in industry and daily life, because it
can protect the substrate or surface from corrosion or moisture, which will help to
prolong the lifetime of coated materials. In this project, the objective is to synthesize
new coating materials based on soybean oil and reactive silanes, and this new coating
material should enhance water the resistant properties of the coated substrate.
Soybean oil can provide water resistant property, but since it is oily and has no
functional groups to form a network to cure, this indicates that we need to find a
reaction that can graft silanes onto the backbone of soybean oil to help to form the
network and to make this coating curable.
A grafting reaction attaches a monomer or monomers onto the backbone of a
polymer or another medium to provide or to improve certain properties of this
medium. Grafting reactions can be achieved by free radical, anionic, cationic or
condensation mechanisms. [1-5] Normally, a grafting reaction system consists of a
reactive polymer or medium, an active monomer and low concentration of a
homopolymerization inhibitor compound. [6]
Unsaturated soybean oil is one kind of reactive vegetable oil, and the reactivity
is from the double bonds. Extensive reactions have been done on this unsaturated
bond to synthesize compatibilized blends via high temperature and high pressure
reactors. [7] Epoxidized soybean oil is another kind of reactive vegetable oil. Epoxy
groups can be polymerized by ring opening reaction to form polymerized epoxidized

11

soybean oil, and these polymers can later be hydrolyzed to hydrogels, which could
further find applications in medical or health care areas. [8]
The Parr reactor has been designed for high temperature and high pressure
reaction systems. A typical Parr reactor has three parts, which are head, cylinder and
controller. A gasket is used to seal the head and the cylinder together. The head part’s
Parr Instrument Company

4520 Bench Top Reactors

scheme is shown below. (Figure 4)
Pressure Gage

Thermocouple
Gas Inlet Valve
Coupling for Gas Hose
Connection

Plug (extra port)
Gas Release Valve

Liquid Sampling Valve

Adapter Bushings

Stirrer Shaft Assembly

Thermowell

Adjustable Impeller

Dip Tube with Nut

Stirrer Support Bracket

Figure 4 Scheme of the head part of Parr Reactor
A gas inlet valve and gas release valve are often used to purge the reactor or to
pressurize the system before reacting. Users can take liquid samples during the
reaction from the liquid sampling valve. A thermowell is used to measure the

12

Pressure Gage

Inlet Sampling Valve

Gas Release Valve

temperature, and a stirrer will enhance the mixture of the reacting liquid. Both the
temperature and pressure can be monitored and adjusted by the controller and the
pressure gauge. Furthermore, parameters of Parr reactor, such as heating time, the
starting pressure and original oxygen concentration in the cylinder, can affect the
viscosity of the product.[9] This result enables us to produce consistent viscosity
products by using this reactor.

2.2 Experimental
2.2.1 Materials
Unsaturated Soybean oil was obtained from Zeeland Farm Services Inc.,
Zeeland, MI. 97% Silanes with a purity of vinyltrimethoxy silane (VTMOS) [CAS
2768-02-7], vinyl terminated polydimethylsiloxane (V-PDMS) [CAS 68083-19-2]
were obtained from Gelest Inc., Morrisville, PA. Luperox 101 (L101) [CAS 78-63-7]
-2,5-Bis (tert-butylperoxy)-2,5-dimethylhexane (90% technical grade) used as the
peroxide catalyst was obtained from Sigma Aldrich, St. Louis, MO. All the reagents
were used as received without any further purification.

2.2.2 Synthesis of silylated soybean oil
There are approximately five double bonds in 1 mole of soybean oil, so three
different molar ratios of reactants were applied to synthesize different silylated
soybean oil products. Two reactions were processed with 1:3 and 1:7 molar ratios of

13

soybean oil and VTMOS, the other one had the molar ratio of 1:2:0.5 of soybean oil,
VTMOS and V-PDMS.
A calculated weight of soybean oil, VTMOS and V-PDMS were mixed in a
closed flask. L101 (1wt% of soybean oil) was added into this mixture as the peroxide
initiator. The mixture was then poured into a 2L Parr reactor produced by Parr
Instrument Company. An external controller was used to set and control the
temperature of the reactor. Reaction temperature was set at 280C. The stirrer was kept
at the speed of 200 rpm to mix the reactants and to uniform the heat.
Before the reaction began, nitrogen was purged into the cylinder of the Parr
reactor for about 2 minutes to exclude air from the system. A high-rate heating was
chosen for the early period of heating stage, and then we switched it to low-rate
heating when the temperature reached 180℃. The reaction time started when the
temperature reached 280C and maintained for 12 hours.
10 samples were taken via the sampling valve into vials. Three of them were
taken during heating period at various time intervals, and the other seven were taken
every two hours after the reaction time started. All the samples were sealed and frozen
in the refrigerator prior to analysis to prevent unreacted VTMOS escaping from the
sample.

2.2.3 Purification of silylated soybean oil products
The final product of this reaction was a mixture of silylated soybean oil,
unreacted silane and unreacted oil. To calculate the reacted VTMOS percentage and
reaction conversion, distillation was used under reduced pressure to remove unreacted

14

VTMOS from the oil products. A large three-neck flask was used as the container to
hold the entire product. The middle outlet was connected with a vacuum, another
outlet was equipped with a thermometer, and the third one is closed with a hollow
plug. A magnetic stirrer was used to completely drive out volatile VTMOS. The
silylated soybean oil product was purified at 110C with the vacuum about 0.3 Torr for
1 hour, or till there was no further distillate generated. The unreacted VTMOS was
trapped in dry ice and acetone traps and weighed.

2.2.4 Iodine value of silylated soybean oil products
The iodine values of silylated soybean oil products were measured according
to ASTM D1959. Both the products after purification and pure soybean oil used in
this reaction were measured to compare the values before and after reaction. Sample
weights were calculated using the conversion obtained earlier and assuming that there
was no change of the number of double bonds on the oil.

2.2.5 TGA
Thermo gravimetric analysis was conducted by a TA Instrument Q 2950 high
resolution thermogravimetric analyzer. Pure soybean oil, pure VTMOS and 1:3 oil
product samples were tested through certain heating profile to separate components’
contents in the final product. The heating profile was by starting at the room
temperature, and then to heat till 150°C by the heat rate of 20°C per minute. After
keeping isothermal stage at 150°C for 20 minutes, ramp up the temperature to 300℃
with the heating rate of 10°C per minute.
15

2.2.6 FTIR
Infrared spectra were obtained with a PerkinElmer 2000 FTIR spectrometer.
Each spectrum was obtained with at least 16 scans to ensure a high signal-to-noise
ratio. The wavelength range was between 4000 cm-1 to 450 cm-1.

2.2.7 NMR
Both proton NMR and carbon NMR spectra were obtained with a Varian 500
MHz superconducting NMR-Spectrometer operating at 499.738 MHz interfaced with
a Sun Microsystems Ultra5 UNIX console. The solvent was CDCl3 with single peak
at 7.24ppm in proton NMR and triplet at 77ppm in carbon NMR. Standard acquisition
parameters were used for the proton spectra and a recycle delay of 2 seconds was used
for the carbon spectra.

2.2.8 Molecular weight measurement
Molecular weight distribution of original reactants and final products was
measured by Gel permeation chromatography (GPC). The output of a GPC reflects
the residence time of a given polymer chain, which is directly related to the molecular
weight of the sample. From a GPC output, the number average molecular weight,
weight average molecular weight and polydispersity index were calculated in
comparison to standards. The polydispersity index (PDI), which indicates the
distribution of individual molecular masses in a batch of polymers, is calculated by
the weight average molecular weight divided by the number average molecular
weight.
16

2.3 Results and Disscussion
2.3.1 Mechanism of silylated reaction
The reaction between unsaturated soybean oil and the silane with a vinyl
group in the presence of peroxide happens at the double bond and vinyl group. There
are three possible reaction pathways for this reaction:
1. An Alder – Ene type reaction, where the double bond on the soybean oil
acts as the ene and the silane acts as the enophile. The silane is grafted onto the
molecular chain of the oil by forming another adjacent double bond.
2. A Diels – Alder type reaction, where conjugated double bonds in the oil
react with the silane to form a ring on the molecular chain of the oil. In this reaction
pathway, the soybean oil acts as the diene and the silane acts as the dienophile.
3. Peroxide mediated grafting of the silane onto the fatty acid backbone in the
oil.
Since the temperatures involved in the present reaction are fairly high, the
most possible reaction pathways might be the Alder – Ene reaction and the grafting
reaction. The Diels – Alder reaction could have a strong reversal reaction at these
temperatures.
The reaction pathways are illustrated as follows.

17

Figure 5 Alder - ENE reaction pathway between VTMOS and soybean oil

Figure 6 Diels - Alder reaction pathway between VTMOS and soybean oil

18

Figure 7 Peroxide mediated grafting pathway between VTMOS and soybean oil
From the above schemes, we can deduce that the Alder – Ene reaction does
not affect the number of double bonds on the soybean oil, while the Diels – Alder
reaction causes a reduction of one double bond on the vegetable oil chain per grafting.
Moreover, Diels – Alder reaction can only happen between conjugated double bonds
on soybean oil and vinyl group on silane, and the reaction molar ratio of conjugated
double bonds and vinyl group is restricted to 1:1. For peroxide mediated grafting, the
number of double bonds on the oil will remain unchanged, which is quite similar to
the Alder – Ene reaction.
We can use iodine values to determine which reaction pathway happens
between soybean oil and VTMOS, because iodine values will indicate the
concentration of double bonds in the products, which could clearly distinguish
products from different reaction pathways.

2.3.2 Iodine values of reactants and different reaction products
The iodine values of pure soybean oil, pure VTMOS and products (after
removal of unreacted VTMOS) made from different reaction ratios are listed in the

19

Table 1. Due to the consumption of one double bond on soybean oil chain during the
Diels – Alder reaction pathway, the corresponding decrease of iodine value will
represent this pathway.

Table 1 Iodine values of original reactants and silylated products
Sample

Content

Sample weight/g

IV

1

Pure Soybean Oil

0.17

157.1

2

Pure Soybean Oil

0.18

151.6

3

Pure VTMOS

0.24

161.2

4

Pure VTMOS

0.28

160.3

5

1:2:1 oil product

0.21

75.5

6

1:2:1 oil product

0.20

80.3

7

1:3 oil product

0.23

126.6

8

1:3 oil product

0.22

128.0

9

1:7 oil product

0.21

107.7

10

1:7 oil product

0.21

108.2

11

Blank

0.00

Average IV

0.0

154.4

160.8

77.9

127.3

108.0

Above data show that the iodine value decreased in the product of soybean oil
and VTMOS compared to pure soybean oil. This indicates that a portion of VTMOS
did react with soybean oil and graft on the molecular chain of soybean oil, the number
of double bonds decreased in the product which caused the change in iodine value.
Also, it can be pointed out that most of the products were formed through either the
Alder – Ene reaction or the peroxide mediated reaction.

20

2.3.3 Mass balance and reaction conversion of silylated reaction
From the purification in Chapter 2.2.3, we can calculate the mass balance and
grafting percentage of this soybean oil and VTMOS reaction. (Table 2) The weight
loss after purification was due to the unreacted VTMOS in this oil product. So the
grafting percentage was based on the weight loss.

Table 2 Mass balances and grafting percentages of 1:7, 1:3 and 1:2:1 silylation
reactions
Molar ratio of
Weight of
Grafting
Soybean oil, Weight before Weight after Weight loss
Original percentage
VTMOS and vacuum [g] vacuum [g]
[g]
VTMOS [g]
[%]
V-PDMS
1:7
866.98
595.35
271.63
481.81
43.62
1:3
1086.03
999.75
86.28
360.39
76.06
1:2:1
937.93
844.49
93.44
177.60
47.39

2.3.4 TGA results of silylated soybean oil products
TGA analysis can be used to confirm the reaction ocurred between soybean oil
and VTMOS and V-PDMS, and can be used to determine the conversion of this
reaction. Since the boiling point of VTMOS is 123°C, the isotherm stage temperature
of TGA test for all these products was set to be 150°C, so that unreacted VTMOS can
evaporate sufficiently to give us the correct grafting percentage. Unreacted soybean
oil is quite stable under 300°C, thus during the whole TGA test, there should be no
weight change due to decomposition of soybean oil.
Gravimetric determination of conversion of silane was calculated by the total
amount of silane before reaction divided by the amount of grafted silane after reaction.
The amount of grafted silane can be calculated by subtracting the weight loss through

21

TGA test from the total amount of silane before reaction. 1:3 oil product was applied
by this method to calculate the conversion, conversion and later compared with the
theoretical expected and the conversion calculated from purification, with excellent
agreement.
Pure soybean oil remained unchanged in weight during TGA test. (Figure 8)
350

100

Weight Loss

80

300
250
200

60

Temperature

40
20

150
100
50

0

0
0

10

20
30
40
Time [min]
Figure 8 Pure soybean oil TGA weight loss plot

Figure 9 1:3 molar ratio oil product TGA weight loss plot

22

Temperature [C]

Weight Loss [%]

120

350

7

300

6

250

dW/dT

5
4

200

3

150

2

100

1

Temperature [C]

8

50

0
-1 0

10

20
30
Time [min]

40

50 0

Figure 10 1:3 molar ratio oil product TGA derivative plot
For the 1:3 molar ratio product, the initial weight of testing sample was
15.43mg, and we can calculate that there was 10.22mg of soybean oil and 5.21mg of
VTMOS in this mixture before grafting reaction. There were two degradation modes,
one was prior to 6.3 min and the other one is after 6.3 min, which can be seen in the
derivative plot (Figure 10). Unreacted VTMOS had evaporated even before the
isotherm stage, which caused the first degradation. After that, the product itself began
to degrade because it has poor temperature stability compared with soybean oil. So
the grafted percentage of VTMOS should be calculated at the time of 6.3min and the
percentage was 80.32%. Detailed calculations were shown in Table 3.

Table 3 Calculation table of grafting percentage of 1:3 oil product from TGA data
Soybean Oil
VTMOS
Total weight
MW (1:3 molar ratio)
900
149*3=447
1347
Initial weight before reaction 10.22mg

5.21mg

15.43mg

Final weight after isotherm

4.19mg

14.41mg

10.22mg

Grafted (%)

80.32%
23

Compared with 76.06% conversion of grafting calculated by purification, this
conversion from TGA is reasonable.

2.3.5 FTIR results of silylated soybean oil products
Oil samples taken during the reaction were examined by FTIR spectrum to
confirm the reaction occurred, and to determine the reaction kinetics parameters. The
following plot is the FTIR spectrum for 1:3 original reactants (soybean oil and
VTMOS blend) and final product after 12 hours reaction. (Figure 11) The red curve is

Absorption

original reactants and the blue curve is final product.

-1

Wavenumbers (cm )
Figure 11 FTIR spectrum for comparison of original reactants (red line) and final oil
product (blue line)

24

-1

The wavenumber range for Si-C bond vibration was 850-650 cm , [10] and
there was a broad peak around 800 cm

-1

in the final product while peaks were

separated in the original reactants, this could demonstrate that VTMOS was
successfully grafted onto soybean oil chain.
Comparing these two samples around the same region, we can see the

Absorption

difference before and after reaction. (Figure 12)

-1

Wavenumbers (cm )
Figure 12 Comparison of FTIR spectrum for original reactants (red line) and final oil
-1
product (blue line) around 800 cm
-1

The tendency to form this 800 cm peak could be monitored by combining the
FTIR spectrum of the 9 samples. (Figure 13)

25

Absorption

-1

Wavenumbers (cm )
Figure 13 Comparison of FTIR spectrum for all samples taken during reaction
Since the absorption area of each peak is proportional to the content
percentage of each bond, by plotting the peak area change vs. reaction time (Figure
14), we could get the kinetic constant and reaction order for this grafting
reaction.[11,12]

26

Peak Area Change (%)

8
y = -0.4048x + 7.2876
R² = 0.97169

7
6
5
4
3
2
1
0
0

5

10
15
20
Reaction time (hours)
Figure 14 Peak area changes of samples in FTIR v.s. reaction time

so

−

dCa
= -0.404 Ca+7.287
6.9853 + 0.5799Ca − 0.1275Ca 2 − 0.0168Ca 3 + 0.0006Ca 4
dt

where Ca is the concentration of original soybean oil in the reaction system.
Compared to the power law model, −

dCa
= kCaα , the order of this reaction
dt

is between 0 and 1.

2.3.6 NMR results of silylated soybean oil products
1:3 Oil product was treated under vacuum to remove the unreacted VTMOS
and then used as NMR sample. Pure soybean oil was also tested for comparison.
(Figure 15) The proton and carbon NMR spectra were provided in Figure 16 and
Figure 17. The assignments for the oil have been made from reported literature on
fatty acid residues [13-15] and silylated hydrocarbons [16, 17].

27

Chemical Shift (ppm)
Figure 15 1H-NMR spectrum of pure soybean oil with peak assignments
Before reaction, there was no significant peak around 3.5 ppm in the proton
NMR spectrum of soybean oil, in which area these peaks correspond to the methoxy
groups in the structure. After reaction, peaks at 3.55 ppm arise, also the sharp singlet
at 3.6 ppm arise, which corresponds to the methoxy group of a methyl ester. This
could be the result of small extent of transesterification at the high temperatures used
in the reaction. The double bonds in the soybean oil remain unaffected.
The integration in proton NMR of the oil product shows that about 2.5 mole of
VTMOS grafted onto soybean oil, which meets the grafted percentage calculations by
using TGA and iodine values.

28

Figure 16 1H-NMR spectrum of 1:3 oil product with integration
In carbon NMR spectrum of the oil product, Peaks at 50 – 51 ppm are the
methoxy peaks of the silane, which indicates that VTMOS has been grafted onto
soybean oil chain.

29

Figure 17 13C-NMR spectrum of 1:3 oil product

2.3.7 Molecular weight results of silylated soybean oil products
The calculated average molecular weights of 1:3 silylated soybean oil product
and pure soybean oil are shown in Table 4.

Table 4 Average molecular weights and PDI of 1:3 oil product and pure soybean oil
Sample

Mn [Da]

Mw [Da]

PDI

Pure soybean oil

735

893

1.21

1:3 oil product

947

6722

7.10

30

From the data, we can clearly see that after 12 hours reaction, the molecular
weight of the oil increased and the PDI broadened. This demonstrates that the
VTMOS has grafted onto the soybean oil chain.

31

REFERENCES

32

References
1. K.C. Gupta, K. Khandekar, Abstracts of Papers, 229th ACS National Meeting,
San Dieno, CA, United States, March 13-17,2005 (2005), POLY-009
2. W.H. Ohrbom, P.A. Herrel, J.W. Rehfuss, U.S. Patent Application Publish
(2003), 8pp. US 2003100687
3. R.E. Delacretaz, A. Stein, R.L. Walter, U.S. Patent Application Publish (1967),
5pp. US 3328488 19670
4. R.J. Hoxmeier, R.C. Job, B.A. Spence, D.A. Dubois, U.S. Patent Application
Publish (1996), 8pp. US 5543458
5. S.H. Lee, K. Yang. Kobunia Kwahak Kwa Kisul (1998), 9(3), 193-199.
6. R. Chatelin, L. Gavet, U.S. Patent Application Publish (1993), 8pp. US
5266632
7. J.W. Veldsink, M.J. Bouma, N.H. Schoon, A.A.C.M. Beenackers. Catalysis
Reviews-Science and Engineering, 1997. 39(3): p. 253-318.
8. Z.S. Liu, and S.Z. Erhan. Journal of the American Oil Chemists Society, 2010.
87(4): p. 437-444.
9. P.I. Chu, and D. Doyle. Pharmaceutical Development and Technology, 1999.
4(4): p. 553-559.
10. K. Sirisinha, and D. Meksawat. Polymer International, 2005. 54(7): p. 7.
11. H. Madra, and S. Tantekin-Ersolmaz. Polymer Testing, 2009. 28(7): p. 7.
12. R. Anbarasan, and V. Dhanalakshmi. Journal of Applied Spectroscopy, 2010.
77(5): p. 7.
13. M. Guillén, A. Ruiz, European Journal of Lipid Science and Technology, 105,
688 (2003).
14. G. Knothe, J.A. Kenar, European Journal of Lipid Science and Technology,
106, 88 (2004).
15. L. Mannina, C. Luchinat, M. Emanuele, A. Segre, Chemistry and Physics of
Lipids, 103, 47 (1999).
16. J. Forsyth, W. Baker, K. Russell, R. Whitney, Journal of Polymer Science
Part A: Polymer Chemistry, 35, 3517 (1997).
17. J. Weaver, Journal of Polymer Science Part A: Polymer Chemistry, 46, 4542
(2008).

33

Chapter 3: Coating performance analysis
3.1 Introduction
Vinyltrimethoxy silane (VTMOS) is an organofunctional silane, with the
structure CH2=CH-Si(OCH3)3. Hydrolysis (1) and condensation reactions (2,3) can
casuse silanes to crosslink and form resins or coatings, and the rates of these reactions
depend on temperature, pH and moisture content. [1] The reaction formulas are
provided below.

CH 2 =CH-Si(OCH 3 )3 + 3H 2O → CH 2 =CH-Si(OH)3 + 3CH 3OH
CH 2 =CH-Si(OH)3 + (OH)3Si-CH 2 =CH
→ CH2 =CH-Si(OH)2 -O-(OH)2Si-CH 2 =CH + H 2O

CH2 =CH-Si(OH)3 + (OCH 3 )(OH)2Si-CH2 =CH
→ CH2 =CH-Si(OH)2 -O-(OH)2Si-CH2 =CH + CH 3OH

(1)

(2)

(3)

After introduction to the soybean oil chain, VTMOS with methoxy group in its
structure will react with moisture in the atmosphere to crosslink and cure the oil
product, to form a coating layer on the surface of paper or steel.
The application of silylated soybean oil as a coating material provides be an
alternative way to synthesize polymers from bio-based and biodegradable materials.
[2] With the advantages of biodegradation and recyclability, coatings made from
silylated soybean oil will largely reduce the use of petroleum-based chemicals,
providing a more sustainable and environmentally friendly capability.

34

Moreover, bio-based silylated soybean oil coatings containing fatty acid chain
are hydrophobic and have limited liquid water and water vapor barrier properties; it is
thus possible to develop further applications incorporating hydrophilic substances
such as paper, wood and starch foam to improve the impermeability of these
substances. [3]

3.2 Different coating systems of paper coating
The several methods used for paper coating used were; direct oil coating
system, a simple emulsion system, an emulsion system with calcium carbonate, and
an emulsion system with silica.
Direct oil coating system. Direct oil coating system involves simply applying
the oil products obtained from the last synthesis step on paper and curing it to get the
coating. However, since the paper readily absorbs the product, it was necessary to
increase the viscosity of the oily products to some extent before application to the
paper. A certain amount of moisture and cure catalyst (dibutyltin dilaurate, DBTDL)
should be added into the oil product to accelerate the crosslinking before application;
also some heat could help to increase the viscosity. This step is called the pre-curing
step. A typical pre-curing step can be achieved by heating and stirring the oil product
for a period of time and mix it with 4 wt % (of oil product) water and 1 wt % (of oil
product) of DBTDL catalyst.
Emulsion system. Emulsion system is a mixture of two or more immiscible
liquids. [4] It is not like two separate phases, rather it is formed by dispersing liquid
droplets with diameter of approximately 1-100 µm into another liquids, to form an

35

emulsion which is stable and uniform under certain conditions. In this project,
silylated oil product was dispersed into water by using sonication. First, the oil
product was mixed with water (70%) and surfactant (3%) on a weight basis. Then this
mixture was stirred well before sonication to ensure that it was exposed to sonication
uniformly. Sonication power was kept constant for (5) and the mixture was sonicated
for 5 minutes. The pre-curing step was still necessary to increase the viscosity of the
coating material to certain extent for application, since the content of water is too high
to retain the coating material on the surface of paper before curing. This was done by
adding 1 wt% (of oil product) of DBDTL catalyst and heating.
Emulsion with calcium carbonate system. Emulsion with calcium carbonate
system was obtained by adding calcium carbonate into the same emulsion made for
emulsion system and sonicating for another 5 minutes. Calcium carbonate is widely
used in the papermaking industry for whitening and surface effects; also it is a
hydrophobic chemical, which could help to improve the water resistant properties.
Nano-sized calcium carbonate was used in this system for good dispersibility. The
precuring step was the same as the one in emulsion system.
Emulsion with Silica powder system. Emulsion with Silica powder system is
20% solid content emulsion with fine silica powder in it. The emulsion was prepared
with 16.7% of oil content and 3.3% of fine silica powder and sonicated for 5 minutes,
and this emulsion was pre-cured by the same method as in the emulsion system.
Although silica powder is hydrophilic, it has better adhesion to the emulsion coating
system than calcium carbonate.
All these pre-cured coating systems were poured onto paper and different
wire-wound rods from BYK Instrument Company together with a flat glass board

36

were used to coat the material on the paper by drawing down the rod uniformly and
quickly on the paper, thus producing different thicknesses of the coating. The coated
paper was cured in an oven for 12 hours at approximately 70°C.

3.3 Coating procedure and curing conditions for paper coating
3.3.1 Pre-curing of oil products
This step is commonly applied for building up the viscosity of oil products to
improve surface energy and spread ability on the paper, which enhances the following
coating or grafting procedure. [24] 4 wt% (of oil product) of distilled water and 1wt%
(of oil product) of DBTDL were added and mixed with the oil product. The mixture
was heated at 75°C until the viscosity was almost the same as glycerol. Normally, the
heating time was 10 minutes.

3.3.2 Coating
The pre-cured oil product was poured on the beginning edge of paper with
adequate amount. The coating apparatus was used to uniformly and quickly draw
down the desired coating thickness on the paper.

3.3.3 Curing
The coated paper was left 24 hours at room temperature to absorb moisture
from the air for curing, and then placed in the oven at 60°C until fully cured.

37

3.4 Property Characterization
3.4.1 Water Vapor Transmission Rate Measurement
Water vapor transmission rate is the rate of water vapor which permeates
through materials. It is also known as moisture vapor transmission rate (MVTR). The
moisture permeability of the substance can be characterized to some extent by
measuring WVTR. Since our goal is to synthesize bio-based coating material with
water resistant property, low WVTR values for the coating are important.

3.4.1.1 Literature review
At the same time as the “Dow unit” for the permeability coefficient was being
created, water vapor barrier was also a topic of interest. The standard method for
determination of moisture barrier, commonly termed WVTR or MVTR, was to
employ a desiccant to determine, by weight gain, how much moisture got through the
barrier and was absorbed by the desiccant. In the experimental setup, the desiccant
was on one side of the barrier material (film or package) and the system was exposed
to high humidity. As permeation occurred, water vapor passing through the barrier
material was absorbed by the desiccant, increasing the weight of the system. It was
assumed that the water vapor partial pressure inside the package was constant at 0, so
once a steady state transmission rate was reached, the rate was the WVTR of this
barrier material. This method is known as “dry cup method”. [5]
Nowadays, the more commonly used method to measure WVTR is called “wet
cup method”. Instead of putting desiccant to maintain 0% reactive humidity (RH), a
dish of distilled water is placed on one side of the barrier material to maintain 100%
38

RH. The driving force of water is the difference between the exterior relative
humidity (translated to a partial pressure or concentration) and 100% RH (the internal
value). [6]
The units of WVTR is

g mil
. There are two important information in
100 in 2 day

this units. First, the amount of permeation is expressed in terms of mass, rather than in
terms of a volume of gas (at STP). It is much less confusing to discuss mass transfer
with amounts that are independent of the temperature and pressure at which
measurements are made. Second, there is no driving force in the units – no partial
pressure difference. Obviously, the amount of water vapor transmission is strongly
affected by (in fact is proportional to) the difference in chemical activity (and hence
the difference in partial pressure) on the two sides of the material. So, reporting what
this is, or calibrating with it, is an essential element. Typically, the users of WVTR
report the WVTR value with conditions at which the value was measured. As a result,
WVTR values are not compatible even in similar situations and it is necessary to
correct for the difference in driving force between the WVTR measurements before
comparing these values.

3.4.1.2 Method
This test was done by using the ASTM F1249 as the standard test method, and
the equipment for this test was the Mocon Permatran-W from Modern Controls Inc. in
the School of Packaging.

39

The test material was the Kraft paper coated with the silylated soybean oil
product, which was made from soybean oil and vinyl trimethylsilane in Chapter 2.
Paper with different thicknesses was tested to determine how the thickness of the
coating affected transmission rate of the coated paper.
The paper sample was cut to fit the chamber of the test equipment, and humid
air was flowed into the chamber to create the designed conditions for this test. Since
the paper sample readily absorbed moisture a foil mask method was used to prepare
samples. In this method aluminum foil is attached to the test surface of the paper with
a certain hole in the centre of the foil to reduce the test area and improve accuracy. In
this case, the area of the hole was 3.14 cm2.
The temperature for this test was set to be 30°C and the humidity of the
chamber was about 80% RH. The foil masked side of the paper sample faced the high
humidity. There were two chambers, Cell A and Cell B, with the same test conditions
for duplication.
The conditioning time for this test was 1 hour, and after that the software
collected the data and calculated the transmission rate every half an hour for both
cells.

3.4.2 Water contact angle measurement
Water contact angle is the angle measured at the interface of water and solid. It
is determined by the interactions of gas, liquid and solid interfaces. Water contact
angle can be used to determine whether this surface is hydrophobic or hydrophilic, so
it is an important parameter for surface property of a substance.

40

3.4.2.1 Literature review
Figure 18 is a scheme showing a drop of water over some solid surface.

Figure 18 Scheme of the interfacial tensions and water contact angle of a water
droplet
The contact angle, θ, is related to interfacial tensions through Young’s
equation [7]:

ϒ SG = ϒ SL + ϒ LG cosθC

(4)

where the subscripts S, G, and L represent the solid phase of the substrate, the
gas/vapor phase of the ambient and the liquid phase of the droplet, and θc is the
critical contact angle.
When the droplet settles on the solid interface, it instantaneously forms a
thermodynamic equilibrium between these three phases. At this equilibrium, the
chemical potential in the three phases should be equal, which means the interfacial
energies γ of these three phases should be satisfied in the equilibrium equation:

0 = ϒ SG − ϒ SL − ϒ LG cosθC

41

(5)

For hydrophobic materials, θc must be equal or large to 90 degree, and therefore,

ϒ SG ≤ ϒ SL + ϒ LG

(6)

There are several measuring methods to measure water contact angle, and the
simplest way is with a goniometer, which allows the user to measure the contact angle
visually. A droplet of water is deposited by a syringe pointed vertically down onto the
sample surface, and a high resolution camera captures the image, which can then be
analyzed either by eye (with a protractor) or using image analysis software.

3.4.2.2 Method
Water contact angle was tested in CMSC lab by using contact angle
goniometer. A drop of distilled water was dispersed vertically on the testing coated
paper, and an optical subsystem captured the profile of the droplet on the paper. The
angle formed between the water/paper interface and the water/vapor interface is the
contact angle.

3.4.3 Cobb test
Paper is composed of random fibers; therefore it has a varying degree of
porosity. For a paper coating material with water resistant property, it is very
important to minimize the ability of fluids, especially water, to penetrate paper.
The Cobb test is used for water absorption rate to determine the paper
coating’s water resistant property. It measures surface water absorption in 60 seconds,
and the procedural standards are explained in TAPPI T 441.[8] The more water

42

absorbed, the larger the Cobb test result the lower the water resistant property of the
material.

3.4.3.1 Method
To begin this test the coated paper is first placed on the balance and the weight
recorded.

2 milliliters water are added with an eye-dropper. After 2 minutes the

excess water is removed by shaking and the paper reweighed.

The difference

between the initial weight and the final weight is the amount of water that was
absorbed through the coating into the paper. To get average results for a coated sheet,
5 different spots for one paper sample need to be tested as duplicate and to determine
the uniformity of the coating.

3.4.4 Biodegradability test
Environmental damage by non-biodegradable material is a great concern and
is gaining more and more attention. Although recycling could reduce the damage to
some extent, it is still restricted to certain plastics or materials. Nowadays, scientists
are trying to synthesize materials from renewable, recyclable and degradable
resources. [9, 10]
Biodegradable material is a material which can be partially or fully degraded
by bacteria or other biological means. Biodegradation can be done either aerobically
with oxygen or anaerobically without oxygen. Different environmental conditions,
such as soil or aqueous, will also affect the extent of biodegradation.

43

3.4.4.1 Literature review
As early as 1973, some specific polyesters proved to be biodegradable when
disposed in bioactive environments such as soil. Polyesters are water resistant and can
be melted and shaped into sheets, bottles, and other products, making certain plastics
now available as a biodegradable product. [11]
Later, polyhydroxylalkanoates (PHAs) were produced and used as renewable,
biodegradable plastics. Moreover, the physical properties and biodegradability of
PHAs can be adjusted by blending with other natural polymers. In the 1980’s the
company ICI Zeneca commercialized PHAs to be used for the production of shampoo
bottles and other cosmetic products. [11]
Nowadays biodegradable technology is highly applied in industry to produce
materials for packaging and other disposables. Even plant-based materials, such as
starch or soybean oil, are used to process biodegradable materials to minimize waste
and toxins. [12]
In nature, different materials have different biodegradation rates. Vegetables
and fruits can be fully degraded within 5 days to 1 month. Tree leaves take about 1
year to be fully degraded by bacteria. Plastic bags will take 50 years or even longer to
be degraded. It is obviously impossible for scientists to collect biodegradable data for
50 years to know the biodegradability of one material. To make long-term estimates,
scientists often use respirometry tests. These tests will collect the amount of CO2
released from the system to calculate the biodegradability. Since microorganisms
digest the sample bit by bit and produce CO2, the amount of released CO2 is
proportional to the amount of sample digested, which could be an indicator of
biodegradation. [13]

44

3.4.4.2 Method
This test is done by following the ISO/FDIS 14852 “Evaluation of the ultimate
aerobic biodegradability of plastic materials in an aqueous medium - Method by
analysis of released carbon dioxide”.
The test materials are 1 mil film made by the products of the silylated
reactions with molar ratio of 1:2:1, 1:3 and 1:7 of soybean oil and vinyl
trimethoxysilane (VTMOS). This film was made by coating the silylated soybean oil
products on the Teflon paper and peered off after it was cured. The reference material
is cellulose. Both of these two materials are fine powder with the same calculated
theoretical amount of carbon dioxide (ThCO2).
The test medium was prepared to be the optimized test medium in this
standard. The total volume of the test medium for each sample was 1500 ml. The
inoculum for this test was obtained from the sewage water of the water-treatment
plant at MSU.
Samples were kept in the incubator room at a constant temperature of 25°C in
the dark and were aerated with carbon dioxide free air to maintain aerobic conditions.
The flow rate of the air was about 60 ml/min, and a duplicate experiment for each
sample flask, control flask and blank flask were made under the same conditions.
The production of carbon dioxide derived from the degradation of the test
material was measured, compared to the ThCO2 and recorded as biodegradation
percentage. NaOH solution with concentration of 0.2N was made every day to collect
the released CO2 and a standard 0.2N HCl solution was used to titrate the NaOH
solution to determine the percentage of biodegradation. The interval of measure was
24 hours.

45

The activity of the inoculums was checked and measured by the same method
for the controlled flask and the blank flask. The process of biodegradation is shown in
a curve where carbon dioxide production or biodegradation percentage is plotted as a
function of time.

3.5 Results and discussion
3.5.1 Coating performances
Four different coating systems were applied for paper coating on two different
paper types provided by Wausau Company. Thus, a total of 10 samples were made for
the study of coating performance and property characterization. The information of
each sample is shown in Table 5.
The coating procedure and cure conditions were the same for all the samples,
and the thickness of coating was 1 mil. Sample 1-4 were made by using 1:3 silylated
soybean oil product, and sample 5-8 were made by using 1:2:1 silylated soybean oil
product.
The reasons for not using 1:7 silylated oil product for coating application and
tests are: 1) purified 1:7 oil product, compared to 1:3 oil product, requires a little more
time (2-3 minutes) to cure after added the DBTDL catalyst; 2) the coating from 1:7 oil
product was more brittle, because there was more crosslinking between grafted
VTMOS and soybean oil due to the excess VTMOS during the reaction; 3) VTMOS
is relatively expensive when compared to soybean oil, also the conversion of 1:7
reaction is much lower than that of 1:3 reaction. Hence the 1:3 silylated soybean oil
product is less expensive with better performance.

46

Table 5 Paper coating samples information
Sample #

Paper #

Coating system

1

GN354872

Direct Oil Coating

2

GN353070

Direct Oil Coating

3

GN354872

Emulsion System

4

GN353070

Emulsion System

5

GN354872

Emulsion System with
Calcium carbonate

6

GN353070

Emulsion System with
Calcium carbonate

7

GN354872

8

GN353070

9

GN354872

10

GN353070

Emulsion System with
Silica
Emulsion System with
Silica
Original paper without
coating
Original paper without
coating

For oil product itself, all of these three reactions gave us a uniform stable oily
product with pale yellow color, and the viscosity for each product was quite similar to
soybean oil.
When applied to coat on the paper or panels, 1:2:1 oil product took much more
time in the pre-curing period to build up to required viscosity, and took much more
time for curing. This is because 1:2:1 oil product was made from V-PDMS which has
long Si-O-Si linkages, when grafted onto soybean oil chain and crosslinked, these
linkages have no functional groups to be reacted or crosslinked to be bonded on the
coated substance. Normally, the time of curing for this oil product in direct coating

47

system is twice than the time for 1:3 oil product. But this long curing time could
provide us more time to apply these materials on paper to coat.
By certain coating procedures, all of the four coating systems were
successfully applied on paper to form a uniform and adhesive coating. Emulsion with
calcium carbonate system has the lowest adhesion to coated paper, for calcium
carbonate particles were not stable in emulsion system, so at the curing step, it
precipitated from the emulsion layer to form a layer of powder on the top of coating.
For panels, direct oil coating system was the only possible coating system, since other
systems contain too much water which affects the spread of coating material on
panels.
3.5.2 WVTR results
Both 1:3 and 1:2:1 silylated soybean oil product coating samples were tested
at 30°C, 80% RH chamber.
One set of samples were made from 1:3 silylated soybean oil product, and
different coating thicknesses of samples were tested. The coating system was direct
oil coating system, and the paper was the same which is DOD Kraft paper. The results
of WVTR for this set of samples are listed below. (Table 6)

Table 6 WVTR results of coating samples made from 1:3 oil product with different
coating thickness
Thickness of the coating (mil)
Cell A
Cell B
Average
2

68.609*

68.423

68.516

1

917.844

474.914

696.379

0.5

1147.835

1163.720

1155.778

0

1439.260

>1600

1439.260

2

*The unit for the values of WVTR is gmil/(100in *day)

48

Compared with original paper without coating (thickness of coating is 0),
silylated soybean oil coating could obviously limit the permeation of water vapor,
which to some extent enhanced the water resistant property of the paper.
Along with the increase of coating thickness, the transmission rate dropped
significantly. This indicates that the water resistant property of paper is proportional
to the coating thickness. When thicker coating is applied to paper, it forms more
complicated and intensive crosslinked networks on the surface of the paper. These
networks formed by fatty acid chains, which is hydrophobic, will largely narrow the
original porosity of the paper and help to prevent the water vapor to permeating the
paper.
Another set of samples was made from 1:2:1 silylated soybean oil, and this set
of samples was coated using different coating systems. The thickness of the coating
was 1 mil for all the samples, and the paper used was Paper# GN354872 from
Wausau Company. The results of this set are shown in the following table. (Table 7)

Table 7 WVTR results of coating samples made from 1:2:1 oil product with different
coating systems
Coating System

Cell A

Cell B

Average

Direct oil coating system

508.745*

485.190

496.968

Emulsion system

1146.108

1144.105

1145.107

Emulsion with calcium
carbonate system

197.619

193.572

195.596

Emulsion with silica system

>1600

>1600

>1600

Original paper

>1600

>1600

>1600

2

*The unit for the values of WVTR is gm/(100in *day)

49

Since the original paper sample is very thin and has large porosity, the test
2

failed because the WVTR result is higher than 1600 gm/(100in *day). Emulsion with
calcium carbonate system shows the best water resistant property, for calcium
carbonate precipitate at the top layer of the coating, and calcium carbonate is super
hydrophobic, which results a significant decrease of WVTR. Contrarily, the emulsion
with silica system does not improve much in water resistance, for silica on the top
layer of coating is hydrophilic, which cannot form a barrier to prevent water vapor
going through. The emulsion system does not limit the transmission as much as direct
oil coating system, for the concentration of crosslinked fatty acid chain in the
emulsion system is much lower than the direct oil coating system. When applied onto
paper, the number of fatty acid chains per unit area in emulsion coating is not as large
as that in the direct coating system. In the last set of tests, the WVTR results is related
to the coating thickness, which is the number of fatty acid chain per unit area, that is
why the emulsion system shows less enhancement in water resistant property.

3.5.3 Water contact angle results
1 mil paper coatings with different coating systems were measured the water
contact angle, and the results are shown in Table 8.
Water contact angle indicates whether a surface is hydrophobic or hydrophilic,
and the cut-off point is 90 degrees. Original paper GN354872 is the paper made
without any additives, and original paper GN353070 is the paper with certain
hydrophobic modifications.

50

Table 8 Water contact angle of 1 mil paper coatings with different coating systems
Molar ratio of
Water Contact
silylated
Sample #
Paper #
Coating system
Angle
soybean oil
(Left/Right) [°]
product
Direct Oil
1
GN354872
1:3
96.3/96.7
Coating
Direct Oil
2
GN353070
1:3
104.2/103.0
Coating
3

GN354872

1:3

Emulsion
System

49.3/47.5

4

GN353070

1:3

Emulsion
System

40.0/39.3

1:2:1

Emulsion
System with
Calcium
Carbonate

105.3/106.5

1:2:1

Emulsion
System with
Calcium
Carbonate

116.2/114.0

124.3/123.7

121.0/119.8

5

6

GN354872

GN353070

7

GN354872

1:2:1

Emulsion
System with
Silica

8

GN353070

1:2:1

Emulsion
System with
Silica

9

GN354872

-

10

GN353070

-

Original paper
without coating
Original paper
without coating

84.7/81.3
95.7/93.7

The largest water contact angle shows in the emulsion with silica system. In
this system, emulsion provides hydrophobic property to the paper, and silica powder
plays the role of smoothing the surface. Surface roughness will affect water contact
angle of the surface. Wang et al [14] found out that along with the increase of surface
roughness, the advancing contact angle increases and the receding contact angle

51

decreases, which hence increases the hysteresis. When contact angle is smaller than
90 degrees, increasing roughness will decrease the contact angle, and when the
contact angle is larger than 90 degrees, increasing roughness will increase the contact
angle. In this case, silica reduced surface roughness, thus after coating, paper
GN354872 had larger contact angle than paper GN353070. In emulsion with calcium
carbonate system, the situation is contrary, since calcium carbonate increased surface
roughness of the paper.
Direct oil coating and emulsion with calcium carbonate systems have water
contact angles larger than 90 degrees, which could be considered to have good water
resistant property. For emulsion with silica system, although the water contact angle
was large in this system, compared with WVTR test results, it cannot maintain this
hydrophobic property for a long time, which is a severe shortcoming for water
resistant coating materials.

3.5.4 Cobb test results
1 mil paper samples that coated with different coating systems were measured
the water absorption rate by Cobb test, and the testing samples’ information and
2

results are in Table 9. The testing area was 100 cm for each sample, and the
2

absorption lasted for 2 minutes. Since the water absorption is expressed in g/m , we
can calculate the absorption by using the weight gain.

52

average weight gain of each sample
100cm 2
average weight gain of each sample 10000 cm 2
=
×
100 cm 2
1m 2

water absorption =

= 100 × average weight gain of each sample g / m 2
Table 9 Cobb test results of 1 mil paper coatings with different coating systems
Molar ratio of
Average
Water
silylated
Coating
Sample #
Paper #
weight gain absorption
soybean oil
system
[g]
[g/m2]
product
Direct Oil
1
GN354872
1:3
0.009
0.9
Coating
Direct Oil
2
GN353070
1:3
0.018
1.8
Coating
Emulsion
3
GN354872
1:3
0.024
2.4
System
Emulsion
4
GN353070
1:3
0.109
10.9
System
5

GN354872

1:2:1

Emulsion
System with
Calcium
carbonate

0.009

0.9

0.011

1.1

6

GN353070

1:2:1

Emulsion
System with
Calcium
carbonate

7

GN354872

1:2:1

Emulsion
System with
Silica

0.040

4.0

8

GN353070

1:2:1

Emulsion
System with
Silica

0.041

4.1

9

GN354872

-

0.214

21.4

10

GN353070

-

0.039

3.9

Original
paper without
coating
Original
paper without
coating

53

(7)

From this test results, all the coating systems helped to improve at least 81.31%
of the water resistant property of the original paper GN354872, for the original paper
GN353070, the improvement percentage was 30% by coated with direct oil coating
system and emulsion with calcium carbonate systems. There was no significant
difference between original paper GN353070 and paper coated with emulsion with
silica system, this was because there were already some water resistant additives
added into this paper during paper making, which enables this kind of original paper
basic water resistant property even without coating. Among these coating systems, the
direct coating and the emulsion with calcium carbonate gave the best water resistance
for both two kinds of paper, because the former one has sufficient fatty acid chain
crosslinked network to prevent water absorption, the later one has calcium carbonate
layer on the top of the coating to provide hydrophobic property.
However, the direct coating was very likely to go through the paper to make
the paper transparent, and the calcium carbonate had no bonding to the polymer
coating layer, which obstructs applications of these two coating systems.

3.5.5 Biodegradability test results
Soybean oil is known as fully biodegradable material, while silanes are very
difficult to be degraded due to Si-O bond. The biodegradability of films made with
different molar ratios of soybean oil was tested for both VTMOS and V-PDMS by
following the ISO/FDIS 14852 standard. The figures below show the biodegradability
results of different silylated soybean oil samples.

54

90.00
Percent of Biodegradation, %

80.00
70.00
60.00
1:7 oil product
sample

50.00
40.00

Positive control

30.00
20.00
10.00
0.00
0

10

20
30
40
Days
Figure 19 1:7 silylated soybean oil product film biodegradability plot

100.00

Percent of Biodegradation, %

90.00
80.00
70.00
60.00

1:3 oil product
sample
positive control

50.00
40.00
30.00
20.00
10.00
0.00
0

10

20

30
Days

40

50

60

Figure 20 1:3 silylated soybean oil product film biodegradability plot

55

120.00

Percent of Biodegradation, %

100.00
80.00
1:2:1 oil product sample

60.00

Positive Control
40.00

Pure VTMOS

20.00
0.00
0

10

20
30
Days

40

50

60

Figure 21 1:2:1 silylated soybean oil product film and pure VTMOS film
biodegradability plot
The biodegradation of 1:7 oil product after 30 days was around 29%,
compared to 76% biodegradation of the positive control. The biodegradability of 1:3
oil product was 65.85% after 55 days, compared to the biodegradability of 93.58% of
cellulose. For 1:2:1 oil product, the biodegradability percent is about 52.86% after 49
days, while the biodegradability of pure VTMOS sample is about 8%, compared to
100% biodegradability of cellulose.
All these three silylated soybean oil can be considered as partially
biodegradable materials, which is environmentally friendly and helpful to prevent
environmental damage.

56

REFERENCES

57

References
1. B.N. Zand, and M. Mandavian. Electrochimica Acta, 2010. 55(13): p.
4222-4222.
2. A.B. Reis, C.M.P. Yoshida, A.P.C. Reis, T.T. Franco. Polymer International,
2011. 60(6): p. 7.
3. J. Vartiainen, R. Motion, H. Kulonen, M. Ratto, E. Skytta, R. Ahvenainen.
Journal of Applied Polymer Science, 2004. 94(3): p. 8.
4. Wikipedia. Emulsion. Available from: http://en.wikipedia.org/wiki/Emulsion.
5. Standard 96, A.E., Standard Test Methods for Water Vapor Transmission of
Materials, 1996.
6. Standard 96-95, A.E., Standard Test Methods for Water Vapor Transmission
of Materials, 1996.
7. T.S. Chow. Journal of Physics-Condensed matter, 1998. 10(27): p.
L445-L451.
8. Troubleshooting Tip: Cobb Test. Available from:
http://paperpennypincher.blogspot.com/2010/04/troubleshooting-tip-cobb-test.html.
9. C.S. Wu. Journal of Applied Polymer Science, 2010. 121(1): p. 427-435.
10. M.C. Choi, Y. Kim, C.S. Ha. Progress in Polymer Science, 2008. 33(6): p.
581-630.
11. R.A. Gross, B. Kalra. Science, 2002. 297(5582): p. 803-807.
12. W.D. Luzier. Proceedings of the National Academy of Sciences, 1992. 89(3):
p. 839-842.
13. T.U.O. Waikato. Measuring Biodegradability. Available from:
http://www.sciencelearn.org.nz/Contexts/Enviro-imprints/Looking-closer/Measuringbiodegradability.
14. X. Wang, J. Lu, B. Wang. Journal of Basic Science and Engineering, 2003.
11(3): p. 297-303.

58

Chapter 4: Alternative reactants to synthesize coating material
Silylated soybean oil coating material has two important parts that enable it to
be a water resistant coating material. One is the long fatty acid chain from soybean oil,
moreover there are double bonds on this chain which could be reacted with silane or
siloxane for later crosslinking or curing of this material. The other part is multiple
methoxy groups of the silane, these methoxy groups could hydrolyze to form silanol
groups and then dehydrate to crosslink.
Based on this theory, alternative reactants with unsaturated structure and long
fatty acid chains could be used to replace the soybean oil to synthesize coating
materials, also different kinds of methoxysilane or ethoxysilane could be applied in
this reaction.
4.1 Synthesis of methyl oleate and vinyl trimethoxy silane adduct
Methyl oleate is a C18 fatty acid ester with one double bond at C9. It is
derived from soy feedstocks and is a primary fatty acid methyl ester in biodiesel fuel.
[1]

Figure 22 Methyl Oleate molecular structure

59

Due to the unsaturated structure, methyl oleate can be epoxidized to form
methyl epoxy stearate, which plays an important role as an intermediate in the
production of a wide series of important industrial products and materials such as
lubricants, plasticizers in polymers, pharmaceuticals and biofuel additives. [2, 3]
Guidotti et al. [4] synthesized titanium-silica catalysts from titanocene dichloride and
mesoporous silica, and then used this catalyst in epoxidation of methyl oleate. Results
showed that this catalyst was sustainable and efficient, and high yields of desired
methyl epoxystearate were achieved.
Oxidation of methyl oleate is also a hot topic in research and industry. Methyl
oleate, the main component in rapeseed biodiesel fuel, has high reactivity, which
could make biofuel unstable during the use. Thus, using an oxidation reaction to
convert methyl oleate into methyl stearate is of great importance. Bax et al. [5]
studied the oxidation of methyl oleate in a fused silica jet-stirred reactor with reaction
temperatures from 550 to 1000 K, and pressure of 106KPa. Reaction products were
analyzed by gas chromatography coupled with mass spectrometer. This presents a
new experimental method for the oxidation of methyl oleate.
With unsaturated structure, methyl oleate has the similar reaction functional
group as soybean oil, and we could design the reaction between methyl oleate and
silane to yield coating materials.

60

4.1.1 Experimental
4.1.1.1 Materials
97% purity vinyltrimethoxy silane (VTMOS) [CAS 2768-02-7] was obtained
from Gelest Inc., Morrisville, PA. 70% purity of methyl oleate [CAS112-62-9],
Luperox 101 (L101) [CAS 78-63-7]-2, 5-Bis (tert-butylperoxy)-2, 5-dimethylhexane
(90% technical grade) used as the peroxide catalyst was obtained from Sigma Aldrich,
St. Louis, MO. All the reagents were used as received without further purification.

4.1.1.2 Synthesis of methyl oleate and vinyl trimethoxy silane adduct
Methyl oleate was mixed with VTMOS at the molar ratio of 1:5, L101 was
added at 1 wt% of methyl oleate as the peroxide initiator. The mixture was then
poured into a 2L Parr reactor produced by Parr Instrument Company. An external
controller was used to set and control the temperature of the reactor. Reaction
temperature was set from 180°C to 260°C with 20°C increments. The stirrer was
maintenined at 200 rpm to mix the reactants and to ensure uniform heating.
Prior to the reaction, nitrogen was purged into the cylinder of the Parr reactor
for about 2 minutes to eliminate air. A high heating rate was chosen for the early
period of heating stage, and then switched to low heating rate when the temperature
reached 70% of the final value. The reaction time started when the temperature
reached the set point and lasted for 8 hours.

61

4.1.2 Characterization
The final product of the reaction was a mixture of silylated methyl oleate,
unreacted silane, and unreacted oil. To calculate the reacted VTMOS percentage and
reaction conversion, gravimetric determination by distillation under reduced pressure
was used to remove unreacted VTMOS from the oil products. A large three-neck flask
was used as the container to hold the entire product. The middle outlet was connected
with a vacuum, another outlet was equipped with a thermometer, and the third closed
with a hollow plug. A magnetic stirrer was used to completely drive out volatile
VTMOS. The silylated methyl oleate product was purified at 110°C with the vacuum
of about 0.3 Torr for 1 hour, or until

no further distillate was generated. The

unreacted VTMOS was trapped with two dry ice and acetone traps and weighed.
The iodine values of silylated methyl oleate products were measured
according to ASTM D1959. Both the products after purification and pure methyl
oleate used in this reaction were measured to compare the change before and after
reaction. Sample weights were calculated using the conversion obtained earlier and
assuming that there was no change in the number of double bonds of the oil.

4.1.3 Results and discussion
4.1.3.1 Gravimetric determination and conversion calculation
From the gravimetric determination, the mass balance and grafting percentage
of this methyl oleate and VTMOS reaction can be calculated. The weight loss after
distillation was due to the unreacted VTMOS in this oil product. Thus the grafting
percentage was based on the weight loss. (Table 10)
62

Table 10 Mass balances and grafting percentages of 1:5 silylation reaction at different
reaction temperature
Reaction
Weight of
Grafting
Weight before Weight after Weight loss
Temperature
Original percentage
vacuum [g] vacuum [g]
[g]
[°C]
VTMOS [g]
[%]
180
936.54
384.24
552.30
667.03
17.20
200
939.68
409.82
529.86
669.27
20.83
220
937.93
462.83
475.10
668.02
28.88
240
932.59
555.31
377.28
664.22
43.20
260
947.60
685.74
261.86
674.91
61.22

The grafting percentage of VTMOS and the conversion of this reaction
increases with the increase of reaction temperature. This indicates that the silylation
can be controlled by adjusting reaction temperature.

4.1.3.2 Iodine values
The iodine values of pure methyl oleate, pure VTMOS and products (after
distillation of unreacted VTMOS) made from different reaction temperatures are
listed in the Table 11.
Compared with soybean oil (IV=154.4 in Chapter 2.3.2), the iodine values of
products are not reduced significantly to the pure methyl oleate. This can be explained
by the low reactivity of double bond in methyl oleate. Moreover, these iodine values
suggest that most of the silylation of methyl oleate occurred through peroxide grafting
route.

63

Table 11 Iodine values of silylated oil products, pure methyl oleate and pure VTMOS
Sample

Content

sample weight/g

IV

1

Pure Methyl Oleate

0.36

83.5

2

Pure Methyl Oleate

0.36

87.8

3

Pure VTMOS

0.24

161.2

4

Pure VTMOS

0.28

160.3

5

180°C reaction
product

0.46

70.3

6

180°C reaction
product

0.47

67.8

7

200°C reaction
product

0.54

63.5

8

200°C reaction
product

0.55

62.8

9

220°C reaction
product

0.55

59.3

10

220°C reaction
product

0.55

59.3

11

240°C reaction
product

0.53

51.7

12

240°C reaction
product

0.52

52.5

13

260°C reaction
product

0.52

42.5

14

260°C reaction
product

0.52

46.9

15

Blank

0.0

0.0

Average IV
85.7

160.8

69.1

63.1

59.3

52.1

44.7

64

4.2 Synthesis of epoxidized soybean oil and amino silane adduct
Soybean oil is derived from the second largest crop in the US. [6] The
unsaturated fatty acid chain in soybean oil enables soybean oil to be introduced with
functional groups to modify its properties. Epoxidized soybean oil is made from
modification of soybean oil with epoxy groups. These epoxidized derivatives can be
used in various applications as stabilizers and plasticizers in polymers, as additives in
lubricants, or as components in plastics. [7, 8] Epoxidized soybean oil can also be
converted into polyols to synthesize polyurethane. [9] Liu et al. [10] polymerized
epoxidized soybean oil with the presence of BF3OEt2 as catalyst. Polymerized
epoxidized soybean oil was found to have high crosslinked networks, and the glass
transition temperature of this polymer ranged from -16°C to -48°C.
Amino silane is a chemical with the general formula (X)3SiY, where X is an
alkoxy (–OCH3 or –OCH2CH3 ) or halogen (–Cl) ligand and Y is an
organofunctional group (aminopropyl, methacryloxy, glycidoxy, vinyl, etc.). [11]
With these two functional groups, amino silane could easily hydrolyze in the presence
of moisture, also could be used to make polyurethane. There are mono-, di-, and
tri-aminosilanes with different properties and usage. With the ability to hydrolyze and
to condense to crosslink, tri-aminosilane was chosen in this reaction to synthesize
coating materials.

65

4.2.1 Experimental
4.2.1.1 Materials
Epoxidized soybean oil DRAPEX 6.8 from Galata Chemicals, Southbury, CT.
3-(aminopropyl)tri-ethoxysilane (NH2(CH2)3Si(OEt)3) [CAS 919-30-2] was obtained
from Gelest Inc., Morrisville, PA. All the reagents were used as received without any
further purification.

4.2.1.2 Synthesis of epoxidized soybean oil and NH2(CH2)3Si(OEt)3 adduct
The reaction molar ratio was planned to be 1:1 of amino group to epoxy group,
since the epoxy value of this epoxidized soybean oil was 7.1, the molar ratio of raw
epoxidized soybean oil vs amino silane should be 1:7.1. According to this, 13.75 gram
of epoxidized soybean oil was mixed with 215.76 grams of NH2(CH2)3Si(OEt)3 in a
dry flask. The reaction between these two reactants was fast and exothermic, thus the
reaction conditions were simply to stir the mixture overnight under dry conditions at
room temperature. Prior to the reaction, nitrogen gas was purged into the flask to
eliminate air in the system.

4.2.1.3 Coating application with silylated epoxidized soybean oil
Pretreatment of the steel panels. 3M™ Scotch-Brite™ Hand Pads and cleaner
from NTIC were used to scrub the panels and remove the oxidized surface. The panels
were scrubbed four times in each direction for 10 seconds or more to generate rich

66

foam on the panel. This was repeated after 5 minutes. The panel was washed with
deionized water, dried with a paper towel, and dried in the oven for 5-10 minutes at
60°C. The panels were then cooled to room temperature.
Prepare the coated oil product. Since the oil was used to coat the panels, it was
not necessary to add water. The oil product was mixed with 1 wt% of dibutyltin
dilaurate (DBTDL) at room temperature, and stirred for 5 minutes.
Coat the panels. The coating instrument was used to coat the panel and obtain
a uniform and rapid draw down. The thickness of the coating was 5 mil.
Coat the PE films. Cut the film to size and use the wired rod to draw oil
product on the film to form a uniform coating. The thickness of the coating was 2 mil.
Cure. Leave the coated panel at room temperature to absorb moisture in the air
for curing, and then place the panel into oven at 60°C until fully cured.

4.2.2 Charaterization
4.2.2.1 FTIR
Infrared spectra were obtained with a PerkinElmer 2000 FTIR spectrometer.
Each spectrum was obtained with at least 16 scans to ensure a high signal-to-noise
-1

-1

ratio. The wavelength range was between 4000 cm to 450 cm .

4.2.2.2 TGA
Thermo gravimetric analysis was conducted by a TA Instrument Q 2950 high
resolution thermogravimetric analyzer. Pure epoxidized soybean oil and silylated

67

epoxidized soybean oil product samples were tested through a specific heating profile
to separate components’ contents in the final product. The heating profile started from
room temperature to 220°C with the heating rate of 20°C per minute. After keeping
isothermal stage at 220°C for 20 minutes, the temperaturs was ramped up to 500°C
with the heating rate of 10°C per minute.

4.2.3 Results and discussion
4.2.3.1 FTIR results of silylated epoxidized soybean oil product
FTIR spectra for the original epoxidized spybean oil and the oil product after

Absorption

reaction with amino silane are shown in Figure 23 and Figure 24.

-1

Wavenumbers (cm )
Figure 23 FTIR spectrum of epoxidized soybean oil (green line) and oil product after
reaction (red line)

68

C-N st
Absorption

NH2 δ
Epoxy group shown in
epoxidized soybean oil

-1

Wavenumbers (cm )
Figure 24 Expanded FTIR spectrum of epoxidized soybean oil (green line) and oil
product after reaction (red line)
Before reaction, the peak around 1240 cm-1 represents the epoxy group in the
oil, while in the product, the peak disappears. The strong peaks around 1100cm-1 and
peaks around 950cm-1 and 760 cm-1 arise and represent the C-N stretch and NH2
group, which means that the amino silane was sucessfully grafted and the reaction
occured between epoxidized soybean oil and amino silane.

4.2.3.2 TGA results of silylated epoxidized soybean oil product
Since the boiling point of amino silane is 217°C, the isotherm stage
temperature of TGA test for all these products was set to be 220°C, so that unreacted
amino silane can evaporate sufficiently to give us correct grafting percentage.

69

Unreacted epoxidized soybean oil is quite stable under 300°C, thus during the whole
TGA test, there should be no weight change due to decomposition of soybean oil
before 300°C. (Figure 25)
120

18
16
14

Weight Loss

12

80

10

60

8
6

40

dW/dT

Weight Loss [%]

100

4
2

dW/dT

20

0

0

-2
0

100

200
300
Temperature [C]

400

500

Figure 25 Pure epoxodized soybean oil TGA weight loss and derivative plot

100
Weight Loss [%]

30

Weight
Loss

25
20

dW/dT

80

15

60

10

40

dW/dT

120

5

20

0

0

-5
0

100

200
300
Temperature [C]

400

500

Figure 26 Silylated epoxidized soybean oil product TGA weight loss and derivative
plot
70

The first weight loss period of the product before 220°C was due to the
evaporation of amino silane, since pure amino silane almost all decomposed before
220°C in the TGA test. The second weight loss period in the isothermal stage of
220°C might be due to the partial decomposition of the oil product. And the last
weight loss period after 400°C was the decomposition of unreacted epoxidized
soybean oil. (Figure 26)
To calculate the reaction conversion and grafting percentage, weight loss at
220°C was used as the weight loss due to evaporation of unreacted amino silane.

Table 12 Calculation table of grafting percentage of the reaction between epoxidized
soybean oil and amino silane
Original Sample
weight [mg]

Original
NH2(CH2)3Si(OEt)3
in sample [mg]

Sample weight at
220°C [mg]

Unreacted
NH2(CH2)3Si(OEt)3
[mg]

10.9990

10.3400

2.1810

8.8180

so the grafting percentage was (10.3400-8.8180)/10.3400*100%=14.72%

4.2.3.3 Coating performance
When the oil was coated on the panels, it was transparent at the beginning of
the coating step, after a while, the oil began to gather in the center area of the coated
panel and turned to a milky color. It cured rapidly. The cured panel had a white color
in the center area, and was transparent in the margin area, and it firmly adhered to the
panels.

71

Same color change also occurred when applying this coating material on PE
films. But the coating on films has better spread performance than on the panels.
It is suspected that the color was due to hydrolysis of unreacted amino silane.

72

REFERENCES

73

References
1. B.R. Moser, F.J. Eller, B.H. Tisserat, A. Gravett. Energy & Fuels, 2011.
25(4): p. 1869-1877.
2. K.M. Doll, B.R. Moser, S.Z. Ethan. Energy & Fuels, 2007. 21(5): p.
3044-3048.
3. A. Kleinova, P. Fodran, L. Brncalova, J. Cvengros. Biomass & Bioenergy,
2008. 32(4): p. 366-371.
4. M. Guidotti, E. Gavrilova, A. Galarneau, B. Coq, R. Psaroa, N. Ravasio.
Green Chemistry, 2011. 13(7): p. 1806-1811.
5. S. Bax, M.H. Hakka, P.A. Glaude, O. Herbinet, F. Battin-Leclerc.
Combustion and Flame, 2010. 157(6): p. 1220-1229.
6. S.L. Naeve, Quality of the United States Soybean Crop., in 2006 US Soybean
Crop Quality Survey 2006: The United Soybean Board.
7. B. Gruber, Manufacture of oligomeric fatty acids as lubricating oil additives,
D. Patent, Editor 1993.
8. J.A. Sherringham, A.J. Clark. Lipid Technology, 2000. 12: p. 129-132.
9. P.P. Kiatsimkul, G.J. Suppes, F.H. Hsieh, Z. Lozada, Y.C. Tu. Industrial
Crops and Products, 2008. 27: p. 257-264.
10. Z.S. Liu, and S.Z. Erhan. Journal of the American Oil Chemists Society,
2010. 87(4): p. 437-444.
11. E. Metwalli, D. Haines, O. Becker, S. Conzone, C.G. Pantano. Journal of
Colloid and Interface Sience, 2006. 298(2): p. 825-831.

74

Chapter 5: Conclusions
5.1 Conclusions
The urgent necessity to develop and improve new synthetic routes to synthesize
bio-based coating materials from renewable resources has driven a great amount of
research. In the study of this thesis, one kind of bio-based silylated soybean oil
coating material was successfully synthesized by reacting soybean oil with silane or
siloxane. The synthesized bio-based coating material, silylated soybean oil coating
material, can be characterized by FTIR, NMR, and chemical method to analyze the
structure and degree of grafting, qualitatively and/or quantitatively. Moreover, the
degree of grafting or silylation is controllable by varying reaction conditions.
After applied to paper coating, it is proved to have water resistant property,
which depending on the original reactants molar ratios and coating systems during
coating steps. This coating material could reduce water vapor transmission rate and
increase water contact angle of coated paper, providing hydrophobic properties to
paper. Also, this coating material is partially biodegradable, and can thus be specified
as environmentally friendly material.

5.2 Recommendations
Further study could be done on the kinetics of curing of this coating material.
Since the length of curing time depends on many factors, such as temperature,
moisture content and amount of DBTDL catalyst, experiment design could be used to
separately study how these factors affect the curing time of this coating material.
More study could be focused on how the catalyst affects reaction kinetics or
75

reaction conversion. Currently, L101 was used as the catalyst for silylation reaction.
We can try some other catalyst to optimize the catalyst and the amount of the catalyst.
Further investigation for coating of water sensitive substances could also be
conducted for more applications of this coating material.

76