-
PREPARATION AND CHARACTERIZATION OF PALM OIL BASED
POLYALKYD FILMS AND COMPOSITES WITH MULTI-WALLED
CARBON NANOTUBES
MUHAMMAD REMANUL ISLAM
Thesis submitted in fulfilment of the requirements for the award of the degree of
Doctor of Philosophy in Chemical Engineering
Faculty of Chemical and Natural Resources Engineering
UNIVERSITI MALAYSIA PAHANG
AUGUST 2015
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ABSTRACT
In this research, polyalkyd resins were prepared from palm oil by using polycondensation
reaction. A two-step method viz., alcoholysis and esterification was conducted to
synthesize polyalkyd resins. Prior to alcoholysis, crude palm oil was subjected for
dehydration process to increase its unsaturation. Different types of catalysts such as,
sulphuric acid, para-toluene sulfonic acid, phosphoric acid, sodium hydrogen sulphate and
potassium hydrogen sulphate were used for the dehydration. In alcoholysis process, the
triglyceride-based dehydrated oil was reacted with glycerol to produce monoglyceride. The
prepared monoglyceride was further brought into contact with acid anhydride to prepare
polyalkyds. Response surface methodology was used to optimize the reaction parameters
for esterification like reaction temperature, reaction time, catalyst concentration, acid
anhydride to mono-glyceride ratio and agitation speed. The optimum condition was used to
prepare various types of polyalkyds by using different types of acid anhydrides such as,
maleic anhydride, succinic anhydride, phthalic anhydride, 3,4,5,6-tetrahydrophthalic
anhydride and cis-1,2-cyclohexanedicarboxylic anhydride. A comparison was drawn
among the resins prepared by using different types and percentages of acid anhydrides.
The produced bioresins were characterized for physico-chemical properties such as,
viscosity, density, iodine value, acid value, drying time, non-volatile materials content,
specific gravity, colour, etc. The resins prepared with optimum reaction parameters were
subjected for curing process by using methyl ethyl ketone peroxide and cobalt
naphthanate. To enhance the resinous property, multi-walled carbon nanotubes
(MWCNTs) were dispersed into the resin at different percentages of loading such as, 0.5,
1.0 and 1.5 wt.%. The loading was optimized based on the tensile strength of the film.
Finally, in-situ polymerization with carbon nanotubes during esterification was performed
by adding optimum percentage of loading. The films produced from different formulations
were characterized by different testing such as, adhesion, chemical resistivity,
thermogravimetric analysis, differential scanning calorimetry, field-emission scanning
electron microscopy, x-ray diffraction analysis, contact-angle measurement, tensile testing,
pencil hardness, gloss, etc. In addition, the curing kinetics of the resin was analysed to
evaluate the kinetic parameters such as, reaction rate, activation energy and degree of
conversion in terms of time and temperature. Result analyses through RSM revealed a
desirability of 0.985 for the reaction time of 88.64 min. Moreover, 91.5% fractional
conversion was achieved actually, which is close to the predicted value. Analysis revealed
that 3,4,5,6-tetrahydophthalic anhydride-based resin showed improved resinous property
than others due to high degree of crosslinking. It was also found that higher amount of
aliphatic acid anhydrides are responsible for high degree of crosslinking density, whereas
higher thermal stability was ensured by the inclusion of aromatic acid anhydride. Finally,
incorporation of MWCNTs into the alkyd resin enhanced the overall film properties, which
was further improved through in-situ reaction. The physical bonding and mechanical
entanglement were the possible reason for showing improved properties, as revealed from
the analysis.
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ABSTRAK
Dalam penyelidikan ini, resin polialkid telah disediakan daripada minyak sawit dengan
menggunakan tindak balas polikondensasi. Satu kaedah yang merangkumi dua langkah,
alkoholisis dan pengesteran telah dijalankan untuk mensintesis resin polialkid. Sebelum
alkoholisis, minyak sawit mentah telah menjalani proses pendehidratan untuk
meningkatkan ketidaktepuannya. Pemangkin yang berbeza seperti asid sulfurik, para-
toluena asid sulfonic, asid fosforik, natrium hidrogen sulfat dan kalium hidrogen sulfat
telah digunakan untuk proses pendehidratan minyak sawit. Dalam proses alkoholisis,
minyak berasaskan trigliserida yang terhidrat telah ditindak balaskan dengan gliserol untuk
menghasilkan monogliserid. Monogliserid yang terhasil terus ditindak balaskan dengan
asid anhidrida untuk menyediakan polialkids. Kaedah gerak balas permukaan digunakan
untuk mengoptimumkan parameter tindak balas pengesteran seperti suhu, masa tindak
balas, kepekatan pemangkin, nisbah asid anhidrida kepada mono-glyceride dan kelajuan
pengacauan. Keadaan optima telah digunakan untuk menyediakan pelbagai jenis alkyds
dengan menggunakan asid anhidrida seperti anhidrida maleic, anhidrida phthalic, anhidrida
succinic, anhidrida 3,4,5,6 - tetrahydrophthalic dan cis - 1,2- cyclohexanedicarboxylic
anhidrida. Perbandingan antara resin juga dilakukan dengan menggunakan jenis dan
peratusan asid anhidrida yang berbeza. Bioresin yang terhasil telah menjalani ujian ciri
fiziko – kimia seperti kelikatan, ketumpatan, nilai iodin, nilai asid, masa pengeringan,
kandungan bahan-bahan yang tidak meruwap, graviti tentu, warna, dan lain-lain. Resin
disediakan daripada tindak balas parameter optimum akan menjalani proses pengawetan
dengan menggunakan metil etil keton peroksida dan kobalt naphthanate. Untuk
meningkatkan ciri resin, nanotiub karbon berbilang berdinding (MWCNTs) akan
disebarkan ke dalam resin mengikut peratusan yang berbeza seperti 0.5, 1.0 dan 1.5 %
berat. Kemasukan pengisi telah dioptimumkan bergantung pada kekuatan tegangan filem tersebut. Akhirnya, pempolimeran in-situ dengan karbon nanotiub melalui proses
esterifikasi dilakukan dengan menambah bahan mengikut peratusan yang optimum. Filem-
filem yang dihasilkan daripada formulasi yang berbeza telah dicirikan oleh ujian yang
berbeza seperti lekatan, kerintangan kimia, analisis termogravimetri, pengkamiran
pengimbasan kalorimeter, bidang - pelepasan imbasan elektron mikroskop, analisis x- ray
pembelauan, pengukuran sentuhan sudut, ujian tegangan, kekerasan pensil, gloss dan lain-
lain. Tambahan pula, kinetik pengawetan resin dianalisis untuk menilai parameter kinetik
seperti kadar tindak balas, tenaga pengaktifan, tahap penukaran dari segi masa dan suhu.
Keputusan analisis melalui RSM mendedahkan 0.985 didapati dengan tindak balas masa
88.64 min. Selain itu, 91.5 % penukaran yang dicapai menunjukkan data direkod
berhampiran dengan nilai yang diramalkan. Analisis menunjukkan bahawa resin
berasaskan anhidrida 3,4,5,6 - tetrahydophthalic menunjukkan peningkatan ciri resin
daripada yang lain kerana darjah sambung-silang yang tinggi. Ia juga menunjukkan
bahawa peningkatan kuantiti anhidrida alifatik bertanggungjawab bagi peningkatan darjah
ketumpatan Sambung-silang, manakala kestabilan haba yang lebih tinggi dipastikan oleh
kemasukan asid anhidrida aromatik. Akhir sekali, penggabungan MWCNTs ke dalam resin
alkyd yang optimum dipertingkatkan ciri-ciri keseluruhan resin, dengan peningkatan
ketara melalui tindak balas in-situ. Ikatan fizikal dan penyangkutan mekanikal adalah
sebab yang mungkin untuk menunjukkan sifat-sifat baik, seperti yang dinyatakan daripada
analisis.
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TABLE OF CONTENTS
Page No
TITLE PAGE i
STATEMENT OF AWARD FOR DEGREE ii
SUPERVISOR’S DECLARATION iii
STUDENT’S DECLARATION iv
DEDICATION v
ACKNOWLEDGEMNTS vi
ABSTRACT vii
ABSTRACK viii
TABLE OF CONTENTS ix
LISTS OF TABLES xiv
LIST OF SCHEMES xvi
LIST OF FIGURES xvii
LIST OF SYMBOLS xx
LIST OF ABBREVIATIONS xxii
CHAPTER 1 INTRODUCTION 01
1.1 BACKGROUND 01
1.2 PROBLEM STATEMENT 05
1.3 OBJECTIVES 06
1.4 SCOPE 07
1.5 RATIONAL OF THE RESEARCH 07
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CHAPTER 2 LITERATURE REVIEW 09
2.1 INTRODUCTION 09
2.2 VEGETABLE OILS AND THEIR PROPERTIES 10
2.3 POLYMERS FROM VEGETABLE OILS 19
2.3.1 Polyesters 22
2.3.1.1 Optimization process of reaction parameters 27
2.3.1.2 Polymerization reactions and techniques 29
2.3.1.3 Polycondensation reaction 29
2.3.2 Other Polymers 30
2.3.2.1 Oxidative and thermo-oxidative polymers 30
2.3.2.2 Polyurethanes 32
2.3.2.3 Polyester amides 36
2.3.2.4 Vinyl polymers 40
2.3.2.5 Epoxies 42
2.3.2.6 Polyamides 43
2.3.2.7 Metathesis of oils 44
2.4 CURING PROCESS AND CURING KINETICS 45
2.4.1 Dynamic Methods 50
2.4.2 Isothermal Methods 53
2.5 NANO PARTICLE INCORPORATION 54
2.6 CHALLANGES AND DIFFICULTIES 56
2.7 CURRENT CONDITION OF PETROLEUM BASED
RESOURCES
58
2.8 SUMMARY 59
CHAPTER 3 MATERIALS AND METHODS 60
3.1 INTRODUCTION 60
3.2 MATERIALS 62
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3.3 METHODS 64
3.3.1 Dehydration of Oil 64
3.3.2 Oil Characterization 65
3.3.2.1 Acid value 65
3.3.2.2 Iodine value 66
3.3.2.3 Density 67
3.3.2.4 Viscosity 67
3.3.2.5 Fourier transform of infrared (FTIR) spectroscopy 67
3.3.2.6 Nuclear magnetic resonance (NMR) spectroscopy 68
3.3.3 Resin Preparation and Characterization 68
3.3.3.1 Preparation of bio resin 68
3.3.3.2 Optimisation of esterification process 70
3.3.3.3 Curing process of resin 73
3.3.3.4 Curing kinetics analysis 74
3.3.3.5 Non-volatile materials content 78
3.3.3.6 Molecular weight and Polydispersity index 78
3.3.4 Film Preparation and Characterization 79
3.3.4.1 Nano composite film preparation 79
3.3.4.2 Scanning electron microscopy 79
3.3.4.3 Thermogravimetric analysis 79
3.3.4.4 Differential scanning calorimetry 80
3.3.4.5 X-ray diffraction (XRD) 80
3.3.4.6 Tensile properties 81
3.3.4.7 Gel fraction 81
3.3.4.8 Swelling ratio 81
3.3.4.9 Crosslinking density 82
3.3.4.10 Chemical resistivity 82
3.3.4.11 Gloss 82
3.3.4.12 Adhesion 83
3.3.4.13 Solubility 83
3.3.4.14 Pencil hardness 84
3.3.4.15 Wettability 85
3.4 SUMMARY 85
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CHAPTER 4 RESULTS AND DISCUSSION 86
4.1 INTRODUCTION 86
4.2 ANALYSES OF OIL PROPERTIES 86
4.2.1 Structural Properties 86
4.2.2 Physicochemical Properties: Effects of Dehydration 88
4.3 ANALYSES OF RESIN PROPERTIES: OPTIMIZATION OF
ESTERIFICATION THROUGH RSM
91
4.3.1 Factor Analysis 91
4.3.2 Process Analysis 95
4.3.3 Process Optimization 100
4.3.4 Evaluation of Polymerization Reaction and Technique 102
4.4 ANALYSES OF RESIN PROPERTIES: EFFECTS OF THE
TYPES OF ACID ANHYDRIDES
104
4.4.1 Physicochemical Properties 104
4.4.2 Structural Properties 106
4.4.3 XRD 111
4.4.4 Surface Property 112
4.4.5 Crosslinking Density 116
4.4.6 Solubility 116
4.4.7 Pencil Hardness 117
4.4.8 Thermal Properties 117
4.4.9 Chemical Resistivity 120
4.4.10 Summary 121
4.5 ANALYSES OF RESIN PROPERTIES: EFFECTS OF
ALIPHATIC ACID ANHYDRIDE CONTENT
122
4.5.1 Physicochemical Properties 122
4.5.2 FTIR and 1H NMR 124
4.5.3 Curing Kinetics 128
4.5.4 XRD 132
4.5.5 Surface Property 133
4.5.6 Crosslinking Density 136
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4.5.7 Solubility 137
4.5.8 Pencil Hardness 137
4.5.9 Thermal Properties 138
4.5.10 Chemical Resistivity 141
4.5.11 Summary 141
4.6 ANALYSIS THE EFFECTS OF MWCNTS INCORPORATION 143
4.6.1 Tensile Properties 143
4.6.2 Pencil Hardness 145
4.6.3 Structural Properties 146
4.6.4 Surface Property 149
4.6.5 Crosslinking Density 153
4.6.6 Thermal Properties 153
4.6.7 Chemical Resistivity 157
4.6.8 Summary 158
CHAPTER 5 CONCLUSION AND RECOMMENDATIONS 159
5.1 CONCLUSION 159
5.2 RECOMMENDATIONS FOR FUTURE WORK 161
REFERENCES 163
APPENDIX A OPTIMIZATION THROUGH RSM 192
APPENDIX B LIST OF PUBLICATIONS 196
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LIST OF TABLES
Table No. Title Page No.
2.1 Annual oil yield per cultivated hectare [kg ha-1
]. 10
2.2 Viscosity, density and iodine value of some common vegetable
oils.
12
2.3 FTIR data for vegetable oils. 13
2.4 Some representative 1H NMR shift values for vegetable oils. 13
2.5 Common fatty acids, structure and formula. 16
2.6 Common vegetable oils and their fatty acid content. 17
3.1 List of chemicals and raw materials used in this research 63
3.2 Different types of acid anhydrides and their properties. 64
3.3 Reaction details of the dehydration process for different catalysts. 65
3.4 Reactants for the alcoholysis process of palm oil. 68
3.5 Experimental factors and pre-assumed range of values for
esterification.
71
3.6 Full factorial central composite design matrix including five
factors for a single response.
72
3.7 Amount of different acid anhydrides for the esterification reaction
for the preparation of polyalkyds.
73
3.8 Mixing details for the esterification reaction for the preparation of
polyalkyds based on different ratios of aromatic and aliphatic acid
anhydrides.
73
3.9 Mixing details of the curing process. 74
3.10 Different gloss categories at 60o 83
4.1 Physicochemical properties of crude and dehydrated oil 89
4.2 Full factorial central composite design matrix including five
factors for a single response.
92
4.3 Analysis of variance for response surface quadratic model. 94
4.4 The solutions suggested by RSM for the esterification process 101
4.5 The optimum solution suggested by RSM 102
4.6 Properties of various types of resins based on different acid
anhydrides
106
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4.7 XRD parameters for different types of resins based on different
acid anhydrides.
111
4.8 Gloss, gel content, swelling ratio, crosslinking density and
adhesion properties of different resins prepared from different
acid anhydrides.
114
4.9 Pencil hardness of various types of cured resins based on different
acid anhydrides.
117
4.10 Thermal properties of different resins based on different acid
anhydrides.
118
4.11 Chemical resistivity of various types of resins. 121
4.12 Physicochemical properties of various types of resins based on
aromatic and/or aliphatic acid anhydrides.
124
4.13 Total heat of reactions, onset, peak and final temperatures at
different heating rates.
128
4.14 Kinetic parameters for different heating rates. 132
4.15 XRD parameters for different types of resins. 133
4.16 Gloss, gel content, swelling ratio, crosslinking density and
adhesion properties of different resins.
135
4.17 Pencil hardness of various types of cured resins. 138
4.18 Thermal properties of different resins. 140
4.19 Chemical resistivity of the cured resins. 141
4.20 Elongation at break of the films 144
4.21 Pencil hardness of various types of cured resins 146
4.22 XRD parameters for different types of resins. 149
4.23 Gloss, gel content, swelling ratio, crosslinking density and
adhesion properties of different resins
150
4.24 Thermal properties of different resins 156
4.25 Chemical resistivity of the cured resins 158
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LIST OF SCHEMES
Scheme No. Title Page No.
2.1 A triglyceride molecule. 14
2.2 Reactions between glycerol and fatty acids to produce
triglyceride.
14
2.3 Various types of fatty acid chains. 15
2.4 Structure of saturated and unsaturated fatty acids available in
palm oil
19
2.5 Triglyceride molecules with various reactive positions. 20
2.6 Various routes of polymerization from plant based oils. 21
2.7 Ester functional group. 22
2.8 Routes of polyester preparation: (a) polycondensation between
diacids and diols and (b) Ring opening polymerization.
23
2.9 Alchoholysis and poly-condensation reaction of oil with acid
anhydride
24
2.10 Preparation of waterborne alkyds 26
2.11 Oxidative polymerization process. 31
2.12 Reaction between di-isocyanate and polyol to form
polyurethane.
33
2.13 An alternating polyester amide. 37
2.14 Synthesis of HELA (a), N-phthaloyl glutamic acid (b), and
PEA (c).
39
2.15 Epoxidation of oleic acid. 42
2.16 Structure of organic polyamide. 43
2.17 Curing reaction during polymerization of divinyl benzene by
using styrene.
46
2.18 Curing process of unsaturated polyesters. 47
2.19 Curing process of epoxy resin. 48
2.20 Schematic images of MWCNTs (a) and SWCNTs (b) 55
3.1 Alcoholysis (I) and esterification reaction (II-VI). 69
4.1 Mechanism for polycondensation reaction between carboxylic
and hydroxyl functional group containing compound.
103
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LIST OF FIGURES
Figure No. Title Page No.
2.1 Applications of vegetable oil-based polymers. 20
3.1 Process flow diagram 61
3.2 Experimental design of the research 62
3.3 Reaction set up for polyalkyd preparation 70
3.4 Scale of pencil hardness testing from softer to harder hardness. 84
4.1 FTIR spectrum of palm oil. 87
4.2 1H NMR spectrum of palm oil. 88
4.3 3-D curves of agitation vs. temperature (a), agitation vs. time (b)
and agitation vs catalyst concentration (c).
97
4.4 3-D curves of catalyst concentration vs. molar ratio (a), catalyst
concentration vs. temperature (b) and catalyst concentration vs
time (c).
98
4.5 3-D curves of molar ratio vs. agitation (a), molar ratio vs.
temperature (b) and molar ratio vs time (c).
99
4.6 3-D curve of time vs. temperature. 100
4.7 FTIR spectra of the resins based on different acid anhydrides. 107
4.8 1H NMR spectrum of SAR. 108
4.9 1H NMR spectrum of MAR. 109
4.10 1H NMR spectrum of PAR. 109
4.11 1H NMR spectrum of TPAR. 110
4.12 1H NMR spectrum of CDAR. 110
4.13 XRD profiles of different films based on different acid
anhydrides.
112
4.14 Contact angle of different acid anhydrides-based films showing
the wettability.
113
4.15 The FE-SEM images of the surfaces of different films prepared
from different resins based on different acid anhydrides.
115
4.16 Weight vs. temperature curves of different resins based on
different acid anhydrides.
119
4.17 Derivative weight vs. temperature curves of different resins 119
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based on different acid anhydrides.
4.18 DSC thermograms of the various resins based on different acid
anhydrides.
120
4.19 FTIR spectra of the resins based on different aromatic and/or
aliphatic acid anhydrides.
125
4.20 1H NMR spectrum of MA0. 126
4.21 1H NMR spectrum of MA50. 126
4.22 1H NMR spectrum of MA75. 127
4.23 1H NMR spectrum of MA100. 127
4.24 Heat flow vs. Temperature curves for different heating rates. 129
4.25 Degree of conversion vs. temperature plot for the curing process
of palm oil based alkyds.
130
4.26 Degree of conversion vs. time plot for the curing process of
palm oil based alkyds.
130
4.27 Reaction rate vs. temperature curve for the curing process of
palm oil based alkyds.
131
4.28 Reaction rate vs. Time plot for the curing process of palm oil
based alkyds.
131
4.29 XRD profiles of different resins based on aromatic or/and
aliphatic acid anhydrides.
133
4.30 Contact angles of different films. 134
4.31 FE-SEM images of different films. 136
4.32 Weight vs. temperature curves of different resins. 139
4.33 Derivative weight vs. temperature curves of different resins. 139
4.34 DSC thermograms of the cured films. 140
4.35 Tensile strength (MPa) and tensile modulus (MPa) of different
films.
145
4.36 FTIR spectra of different films prepared without MWCNTs,
with MWCNTs (at different loading) and in-situ reacted
MWCNTs.
147
4.37 XRD defractograms of different polymeric films prepared
without MWCNTs, with MWCNTs (at different loading) and in-
situ reacted MWCNTs.
148
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xix
4.38 Contact angles of different polymeric films based on without
MWCNTs and with MWCNTS.
150
4.39 Surface morphology of polyalkyd and different percentages of
MWCNTs filled polyalkyds films.
152
4.40 Weight vs. temperature curves of different films prepared
without MWCNTs, with MWCNTs (at different loading) and in-
situ reacted MWCNTs.
154
4.41 Derivative weight vs. temperature curves of different films
produced without MWCNTs, with MWCNTs (at different
loading) and in-situ reacted MWCNTs.
155
4.42 DSC thermograms of different films prepared without
MWCNTs, with MWCNTs (at different loading) and in-situ
reacted MWCNTs.
156
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LIST OF SYMBOLS
A Pre-exponential factor or Arrhenius factor
α Degree of cure
σt Tensile strength (MPa)
β Heating rate (0C/min)
βo Unknown coefficient in RSM analysis
Βi Unknown coefficient in RSM analysis
Βij Unknown coefficient in RSM analysis
d Interplaner spacing
dα/dt Reaction rate
δij Unknown coefficient in RSM analysis
ε Random error of experimentation
η* Complex viscosity
θ Bragg scattering angle
Ea Activation energy (J mol-1
)
ΔH Heat of fusion of sample
ΔHm Heat of fusion of 100% crystalline reference material
HR Total heat of reaction
ΔHR Heat of reaction
dH/dt Normalized heat generated per unit time
ΔHt Released heat per unit of mass up to the time, t
IDSC Degree of crystallinity (%)
k Rate constant
K Scherer’s constant
m The order of reaction
n The order of reaction
Mn Number average molecular weight
Mw Weight average molecular weight
R Gas constant
Tg Glass transition temperature (0C)
Tm Melting temperature (0C)
Tc Crystallization temperature (0C)
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xxi
Tmax Temperature of maximum reaction rate (0C)
x Reaction order
xi Matrix of the un-coded process variables
xj Matrix of the un-coded process variables
Y Fractional conversion
Yn Fractional conversion
λ X-ray wavelength
Z Frequency factor
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xxii
LIST OF ABBREVIATIONS
ANOVA Analysis of variance
ASTM American standard testing method
AV Acid value
BPH N-benzyl pyrazinium hexafluoroantimonate
CN Carbon number
CFA Cottonseed oil fatty amide
CNT Carbon nano tube
CPEA Cotton seed oil based polyester amide
DA Dimer acid
DB Double bond
DCC Dicyclohexylcarbodiimide
DDA Dicyandiamide
DEA Diethanolamine
DES Design expert software
DGEBA Diglycidyl ether of bisphenol A
DSC Differential scanning calorimetry
DTG Differential thermogravimetry
DOE Design-of-experiment
DVB Divinyl benzene
EB Elongation at break
EMI 2-ethyl-4-methylimidazole
ESO Epoxidized soybean oil
FE-SEM Field-emission scanning electron microscopy
FTIR Fourier transforms infrared spectroscopy
GF Gel fraction
GPC Gel permeation chromatography
HBPEA Hyper branched polyester amide
HBPU Hyper branched polyurethane
HELA N, N-bis (2-hydroxyethyl) linseed oil fatty acid amide
HPLC High performance liquid chromatography
1H NMR Proton Nuclear Magnetic Resonance
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xxiii
IPN Interpenetrating polymer network
LCP Liquid crystal polymer
LOFA Linseed oil fatty acid
LPU Linear polyurethane
MDI Methylene diphenyl isocyanate
MEKP Methyl ethyl ketone peroxide
MG Monoglyceride
MHHPA Methylhexa hydrophthalic anhydride
MPOB Malaysian Palm Oil Board
MTO Methyltrioxorhenium (VII)
MWCNT Multi-walled carbon nano tube
NIPU Non-isocyanate based polyurethane
NPGA N-phthaloylglutamic acid
NV Non-volatile content
PDI Polydispersity index
PEA Polyester amide
PA Phthalic anhydride
PAA Pyromellitimide acetic acid
PHBA p-hydroxybenzoic acid
PMMA Poly (methyl methacrylate)
PTSA Para-toluene sulphonic acid
PU Polyurethane
PUD Polyurethane dispersions
PVA Poly vinyl acid
rpm Revolution per minute
RSM Response surface methodology
SA Succinic anhydride
SR Swelling ratio
SEM Scanning electron microscopy
SIN Simultaneous interpenetrating network
SIPN Sequential interpenetrating polymer networks
SWCNT Single-walled carbon nano tube
TDI Toluene diisocyanate
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xxiv
TGA Thermogravimetric analysis
THF Tetra hydro furan
TS Tensile strength
TTS Time−temperature superposition
VOC Volatile organic compound
XRD
X-ray diffraction
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CHAPTER 1
INTRODUCTION
1.1 BACKGROUND
Polymers as versatile materials are being used in various technical purposes and
applications depending on their varieties of properties. A large range of functional
differences and behaviours has made them to be used in a wide range of applications. They
possess properties like, tough, flexible, brittle, elastomeric, plastic, fibrous, chemically-
inert, non-degradable, biodegradable, crystalline, amorphous, linear, cross-linked,
branched, hyper-branched, non-conductive, conductive, low-density, high-density, hard,
soft, rigid, light-weight, low-molecular weight, high-molecular weight, thermally-stable,
non-flammable, gas-permeable, thermoplastic, thermosetting, etc.
Generally, the monomer and its source of origin (aromatic or aliphatic, organic or
inorganic, natural or synthetic) can decide the dominating properties of polymers. For
example, aromatic originated polymers are found to be high temperature resistant due to
the presence of structurally stable benzene ring (Guner et al., 2006). On the contrary,
aliphatic polymers show relatively lower thermal stability. Except the origin or source of
the polymers, some additives or fillers like, initiator, plasticizer, stabilizer, anti-oxidant,
cross-linker (hardener), curing agent, co-monomer, compatibilizer, coupling agent, etc.
also contribute and support specific roles, which are reflected on the properties showed by
the individuals. The major portions of these polymers are made from organic sources and
mainly consist of carbon, hydrogen and oxygen atoms, although some other inorganic
atoms may be present. The endless numbers of options to create or modify the polymers
have made these materials attractive to the researchers to investigate with.
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2
Innovation of new materials from renewable resources, instead of using fossil feed
stocks, is rising up day by day due to the concerns of low-cost materials, industrial
pressures for new materials and environmental sustainability. Currently, polymers are
being consumed so widely that their production has been reached 365 million tonnes in the
year 2015, and hence petroleum-based polymer industries are growing up everywhere in
the world. Petroleum resources are fixed and limited; there should be some other
alternative resources to meet the uprising demand. Nowadays, polymers from renewable
resources are attracting the researchers to work on those for advance level of researches. In
addition, high price of synthetic polymers, their non-biodegradable nature, involvedness of
significant amount of greenhouse gas emission, huge heat consumption during processing,
scarcity of the raw materials, environmental legislations or restrictions, etc. are also
important reasons for searching bio-based alternatives. The bio-based alternatives should
be inherently biodegradable and annually renewable. Among the renewable bio-based
resources, the triglyceride based vegetable oils (Luo et al., 2013; Tan et al., 2013; Das et
al., 2009a; Altuna et al., 2010; Das et al., 2010), lignin-based plant biomasses (Domínguez
et al., 2013; Xu et al., 2010) and proteins (Blomfeldt et al., 2011) are mentionable
resources from which polymers can be produced.
The current focusing area includes only vegetable oil based biopolymers and their
derivatives with major characteristics features. Vegetable oils and modified oils are being
used as main raw materials for resin preparation. For example, linseed oil and tung oil
were used for coating ingredients in oil paints and varnishes for several decades due to
their fast-drying nature (Samadzadeh et al., 2011; Xiaoyin et al., 1997). Sometimes,
modifications of non-drying oils by drying oils are found to be effective for the preparation
of bio resin. For example, modified palm oil (non-drying oil) was produced by
interesterification process with tung oil (drying oil) for the preparation of water-reducible
acrylic-alkyd resin (Saravari et al., 2005). In other applications, vegetable oil was used
with commercial resin for improved flexibility and solubility (Hintze-Bruning, 1992).
Various polymerization reactions such as, cationic (Lu et al., 2010), condensation (Sharma
et al., 2008), radical copolymerization (Saravari et al., 2005) etc. have been used to
produce various types of polymers. Among the polymers, polyesters or polyalkyds (Blaise
et al., 2012), polyester amides (Pramanik et al., 2013), epoxies (Kim et al., 2012;
Sinadinović-Fišer et al., 2012) and polyurethanes (Das et al., 2013) are mentionable.
Various types of oils such as, soybean oil (Tan et al., 2013), sunflower oil (Das et al.,
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2013), linseed oil (Pfister et al., 2010), castor oil (Sinadinović-Fišer et al., 2012), nahar
seed oil (Dutta et al., 2005), rapeseed oil and jatropha oil (Patel et al., 2008) have been
used for these purposes.
Vegetable oils are triglycerides, consisting of glycerol molecule connected with
three similar or different types of saturated or unsaturated fatty acids. Depending on the
unsaturated conditions or unsaturated fatty acids’ percentages in the oil, the route of their
modification on functional groups can be decided to produce a potential monomeric
molecule (Bailey, 1996). The produced monomer can be subjected for suitable
polymerisation process to formulate bio-polymers. The estimated amount of vegetable oils
that are being utilized to prepare different kinds of coating materials is one million tonnes
(Gunstone et al., 2007). Among the biopolymers, polyalkyds are being used efficiently in
coating industries due to their short drying time, sufficient mechanical strength and
acceptable chemical resistivity. There are several advantages of preparing polyalkyds from
vegetable oils over traditional monomer based raw materials. Especially, the cost involved
to produce plant based polyalkyds is lesser compared to the conventional polyalkyds.
Moreover, it is environmental-friendly and associated with low-energy requirement during
manufacturing. Furthermore, the polymerisation process is easy to control.
The current study deals with the reaction parameters involved in esterification
process and their optimization through response surface methodology (RSM). The
utilization of RSM was used earlier for different process optimization and found
motivational for analysing process parameters (Islam et al., 2013; Uzoh et al., 2013). The
design-of-experiment (DOE) was used for the characterization of the factors of
esterification to obtain a targeted value of response. RSM was used for polyesterification
process of palm oil in previous study (Uzoh et al., 2013). Reported results from the factor
analyses were found to be significant for the optimization process. However, in the current
study, five different types of catalysts were used prior to esterification to improve the
unsaturation in the oil through dehydration process. After that, the best catalyst was chosen
based on the highest unsaturation in the dehydrated oil and considered further for the
esterification process.
Polyalkyds have been manufactured from different types of vegetable oils such as,
palm oil, nahar seed oil, rapeseed oil, jatropha oil, etc. (Uzoh et al., 2013; Issam et al.,
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2009; Patel et al., 2008; Dutta et al., 2004). The properties of these polymers vary due to
the constitutional composition of the fatty acids. Palm oil is non-drying oil and its
unsaturation is lower compared to other drying oils like, tung oil, soybean oil and
sunflower oil. Therefore, the drying time of palm oil based polyalkyds were found to be
longer compared to drying oils-based one. Other properties like adhesion, hardness and
chemical resistivity were also found to be moderate. Earlier, efforts were given to produce
palm oil based polyalkyds, but the documented properties were not standard due to the
presence of higher amount of saturated fatty acids in palm oil, nearly 50% (Issam et al.,
2009). Especially, the drying time was found to be longer compared to that of drying oil-
based polyalkyds. Thus due to non-drying property, palm oil was not explored extensively,
and found discouraging for polymer synthesis. To solve this problem, palm oil based
modified polyalkyds were prepared with drying oil (Ali et al., 2001). In a different study,
due to poor mechanical property, modification or blending of palm oil based polyalkyds
with commercial or petroleum based polyalkyds were studied by previous researchers
(Saravari et al., 2005).
Except the constitutional variations during manufacturing, the curing parameters
are also important to get reflected the desired properties in the formulated resins. For that,
the curing kinetics is an important measure to reveal the nature of the curing process and
other parameters involved. The widely used technique for the curing parameters
determination is differential scanning calorimetry (DSC), established since long time
before (Barton et al., 1985; Mijovic et al., 1984). Earlier, the curing process of different
materials prepared form ester functional groups were analysed by DSC (Mazali et al.,
2009; Jankovi et al., 2010; He et al., 2013; Sultania et al., 2010). In general, the dynamic
and isothermal heating methods are found to be applied for curing kinetics analysis. The
overall curing process can be depicted though single temperatures scan by analysing the
reaction parameters with the help of curing isotherms (Kay et al., 1975). Earlier, the semi-
drying oils such as, castor oil and soybean oil were used for curing kinetics analysis
(Jovicic et al., 2008). A successful transformation of the dynamic DSC data through
Ozawa kinetic model was found to be well-fitted, and the apparent degree of curing had a
significant effect on the hardness of the polymeric films produced (Ozawa, 1970).
Recent studies on the incorporation of nano materials into thermosetting polymers
are found to be effective to improve the thermo-mechanical properties of the matrix.
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Earlier, various nano materials such as, silica, silver and carbon black were used for
different purposes. For example, they were used to enhance the corrosion resistivity, anti-
microbial activity, thermal and mechanical properties (Zhang et al., 2007a; Dolatzadeh et
al., 2011; Dinha et al., 2014). Among them, carbon nano tubes (CNTs) are potential
materials which can be used to improve the film properties of the polyalkyds. The
mechanical behaviour of CNTs and their fabrication process with suitable applications
were discussed elaborately in previous articles (Thostenson et al., 2001; Liu et al., 2004;
Choi et al., 2004). The processing of nanotubes or nanoparticles incorporation into liquid
resin or polymers was found to be a tedious job for a uniform and evenly dispersion, which
was considering a major shortcoming of this material (Gibson et al., 2007). The
agglomeration or cluster formation of nanotubes is the reason for uneven or poor
dispersion of them into the polymer matrix. Thus the aim of this research work is to
disperse CNTs by physical stirring with the help of magnetic rotor in the presence of
minimum frequency of ultrasound and following in-situ reaction technique during
esterification process.
1.2 PROBLEM STATEMENT
Commercially available polymers are derived from non-renewable resources,
mostly from fossil fuels, whose reservations are reducing day by day due to high demand.
These polymers are not environmental-friendly, associated with higher manufacturing cost,
non-biodegradable, and hence encounter disposable problems. During their manufacturing
process, huge amount of heat energy along with greenhouse gas emissions are involved,
which are harmful for the world’s sustainability. All this issues derive the researchers to
find new, renewable, environmental-friendly and bio-based resources for polymer
synthesis.
Recently, polyalkyds from drying oils have drawn interests among the researchers
for their excellent drying property, which is absent in non-drying based polyalkyds. Palm
oil is non-drying oil and the reported drying properties are not up to the level of drying oil
based products, but the production of palm oil is highest compared to other vegetable oils
worldwide. This huge amount can be used for the polymer production for the economic
benefit and sustainability. Moreover, the price of this oil is very less compared to others.
Therefore, improvement of drying property is essential for palm oil based polyalkyds.
Table of content ACH 1 to CH 5 B