TITLE OF THE THESIS
(Uppercase, centred, bold, 18 point gold colored font)
X
OPTIMISATION AND CHARACTERISATION OF
FUNCTIONALISED GRAPHENE NANOPLATELETS
FILLED NR/EPDM NANOCOMPOSITES
MAZLIN AIDA BT MAHAMOOD
MASTER OF SCIENCE
IN MANUFACTURING ENGINEERING
Faculty of Manufacturing Engineering
OPTIMISATION AND CHARACTERISATION OF FUNCTIONALISED
GRAPHENE NANOPLATELETS FILLED NR/EPDM
NANOCOMPOSITES
Mazlin Aida Binti Mahamood
Master of Science in Manufacturing Engineering
OPTIMISATION AND CHARACTERISATION OF FUNCTIONALISED GRAPHENE NANOPLATELETS FILLED NR/EPDM NANOCOMPOSITES
MAZLIN AIDA BINTI MAHAMOOD
A thesis submitted
in fulfillment of the requirements for the degree of Master of Science in Manufacturing Engineering
Faculty of Manufacturing Engineering
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
DECLARATION
I declare that this thesis entitled “Optimisation and Characterisation of Functionalised Graphene Nanoplatelets Filled NR/EPDM Nanocomposites” is the result of my own research except as cited in the references. The thesis has not been accepted for any degree and is not concurrently submitted in candidature of any other degree.
Signature : ………... Name : ………... Date : ………...
APPROVAL
I hereby declare that I have read this thesis and in my opinion this thesis is sufficient in terms of scope and quality for the award of Master of Science in Manufacturing Engineering.
Signature : ………... Supervisor’s Name : ………...
Date : ………...
DEDICATION
To God, who gave me the life, strength and the guidance, to my beloved family, husband, mama, abah, abang, kakak dan adik-adik, thank you for giving me full encouragement and love. To my respective supervisor and lecturer, thank you for the lesson and knowledge. To all
i ABSTRACT
ii ABSTRAK
Pada masa kini, nanokomposit polimer telah menarik perhatian ramai disebabkan oleh prestasi amat cemerlang sifat-sifat bahan ini jika dibandingkan dengan polimer tulen atau komposit konvensional. Penyelidikan ini bertujuan menyediakan dan mencirikan sifat mekanik dan terma nanokomposit adunan getah asli (NR) / etilena propilena diena (EPDM) berpengisi kepingan nano zarah grafin (GNPs). Peringkat pertama penyelidikan dimulakan dengan percubaan menyelesaikan isu ketidaklarutcampuran dan ketidakserasian antara fasa getah NR dan EPDM, melalui penggunaan penserasi MAH grafted EPM. Adunan NR/EPDM telah disebatikan dengan menggunakan peralatan pencampur dalaman Haake dan divulkan secara sistem pematangan separa-EV, berdasarkan ASTM D3192. Metodologi permukaan sambutan (RSM) dari perisian Design Expert 6.0.10 telah digunakan, bagi pengoptimuman parameter pemprosesan dan amaun penserasi MAH grafted EPM, terhadap sifat kekuatan tegangan (TS) yang maksimum. Sambutan yang optimum telah diperolehi dari parameter pencampuran NR/EPDM; 110°C suhu pencampuran, 40 rpm kelajuan rotor, 5 minit tempoh pengadunan dan 5 phr amaun penserasi MAH grafted EPM, dengan kebolehulangan yang tinggi dan nilai R2 sebanyak
~99.00%. Peringkat kedua penyelidikan telah memfokus kepada rawatan permukaan pengisi kepingan nano-zarah grafin secara bukan kovalen, dengan kehadiran polietilenaimina (PEI) dalam medium etanol-air suling (75:25). Mekanisma penjerapan fizikal secara interaksi sterik bukan kovalen GNPs-PEI, telah dicadangkan sebagai mekanisma tindak balas. Pada peringkat ketiga kajian, kesan rawatan permukaan GNPs dan penambahan pengisi yang berbeza (0.25-5.00 bt. %) terhadap kebolehprosesan, sifat mekanik, fizik, terma dan morfologi nanokomposit adalah diselidiki. Rawatan permukaan yang dijalankan keatas GNPs, telah meningkatkan interaksi antara matriks-pengisi dalam nanokomposit adunan getah NR/EPDM. Nanokomposit dengan 3.00 bt. % PEI-terawat GNPs menunjukkan sifat-sifat mekanik yang lebih baik berbanding adunan tidak berpengisi dan adunan berpengisi tidak terawat yang lain (kekuatan tegangan sebanyak 27.78 MPa, 19.65 MPa and 23.34 MPa; masing-masing). Keputusan kajian disokong dengan analisa terma dan dinamik. Pada peringkat terakhir ujikaji, keboleh aliran haba sebanyak 0.6220 Wm-1K-1 menunjukkan adunan NR/EPDM dengan 3.00 bt. % PEI-terawat
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ACKNOWLEDGEMENTS
First of all, my gratitude to Allah S.W.T for giving me the strength to undertake the master’s degree by research sponsored by Ministry of Higher Education through the My Brain 15 (MyMaster) and Fundamental Research Grant Scheme (FRGS).
I would also like to express my sincere gratitude to Universiti Teknikal Malaysia Melaka (UTeM) especially to Centre for Graduate Study (PPS) and Faculty of Manufacturing Engineering (FKP) for giving me the opportunity to further my study. Sincere appreciation to my supervisor, Dr Noraiham Binti Mohamad who has been patiently guiding me throughout the years until the completion of the study. I will remain forever indebted. Thank you so much to my other lecturer and friends, Dr. Jeefferie Bin Abdul Razak, Sharafina, Nadiah, Juliana, khairul Shahril, Anisah, Fevilia, Fariza for their constant help and precious advice on how to pursue the research.
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LIST OF APPENDICES xiii
LIST OF ABBREVIATIONS AND SYMBOLS xiv
LIST OF PUBLICATIONS xvi
CHAPTER
1. INTRODUCTION 1
1.1 Research Background 1
1.2 Problem Statement and Significance of Study 5
1.3 Research Objectives 8
1.4 Scope of Research 9
1.5 Thesis Organisation 10
2. LITERATURE REVIEW 11
2.1 Polymer Nanocomposites 11
2.1.1 Polymer Blends as Matrix Materials 14
2.1.2 Reinforcement Materials 17
2.1.3 Processing of Polymer Nanocomposites 18
2.2 Rubber Blends based Nanocomposites 21
2.2.1 Rubber Blends 21
2.2.2 Miscibility and Compatibility 28
2.2.3 Vulcanisation of Rubber Materials 30
2.3 GNPs based Polymer Nanocomposites 35
2.3.1 Mechanical and Thermal Properties of GNPs 36 2.3.2 Aggregation and Agglomeration of GNPs 37 2.4 Mechanical and Thermal Properties of Polymer Nanocomposites 42
3. MATERIALS AND METHODS
3.1 Introduction 45
3.2 Flowchart of Research 45
3.3 Raw Materials 47
3.4 Stage 1: Preparation and Characterisation of NR/EPDM Blends 50
3.4.1 Design of Experiment (DOE) 50
3.4.2 Melt Blending of NR/EPDM blends (ASTM D 3192) 52 3.4.3 Process Evaluation using Cure Characteristic Studies 54 (ASTM D 2084)
v
3.4.5 Mechanical Tensile Testing (BS 6746) 55 3.4.6 Shore-A Hardness Testing (ASTM D 2240-89) 56
3.4.7 Swelling Test (ISO 1817) 57
3.4.8 Thermal Evaluation by Differential Scanning Calorimetry 58 (DSC)
3.4.9 Fracture Morphology Observation by Scanning Electron
Microscopy (SEM) 58
3.4.10 Decision of Processing Parameters 59 3.5 Stage 2: Pre-Treatment of GNPs Prior to Preparation of
NR/EPDM filled GNPs Nanocomposite Blends 60 3.5.1 Surface Modification and Characterisation of Graphene
Nanoplatelets (GNPs) 60
3.5.1.1 Precipitation Analysis of GNPs in Various
Solvents 60
3.5.1.2 Non-covalent Surface Treatment of GNPs 61 3.5.1.3 Fourier Transform Infrared (FTIR) Spectroscopy 62 Analysis
3.5.1.4 X-ray Diffraction (XRD) Analysis 62 3.5.1.5 Transmission Electron Microscopy (TEM) 62 Observation
3.6 Stage 3: Mechanical and Physical Properties of NR/EPDM 63 filled GNPs Nanocomposite
3.6.1 Melt Blending of NR/EPDM filled GNPs Nanocomposite 63 3.6.2 Mechanical and Physical Properties of NR/EPDM 64 filled GNPs Nanocomposite
3.6.2.1 Cure Characteristic Testing (ASTM D 2084) 64 3.6.2.7 Fracture Morphology Observation by Field
Emission Scanning Electron Microscopy (FESEM) 3.7 Stage 4: Thermal Properties Evaluation of NR/EPDM 66
GNPs Nanocomposite Blends
3.7.1 Heat Dissipation Study using Thermal Conductivity 66 Analysis (TCA) Test
3.7.2 Heat Degradation Study by Thermogravimetric Analysis 68 (TGA)
3.7.4 Dynamic Properties Study using Dynamic Mechanical 68 Analysis (DMA)
3.8 Summary 68
4. RESULTS AND DISCUSSIONS
4.1 Introduction 70
4.2 Stage 1: Optimum Parameters of NR/EPDM blends via RSM 70
4.2.1 Regression Model 70
4.2.2 Interaction between Variables for Cure Characteristics of 72 the Blends
vi Blends
4.2.4 Interaction between Variables for Hardness Properties of 79 the Blends
4.2.5 Decision for Optimum Processing Parameters 80
4.2.6 Swelling Measurement 81
4.2.7 Differential Scanning Calorimetry (DSC) 82 4.2.8 Scanning Electron Microscopy (SEM) Observation 84
4.2.9 Summary 86
4.3 Stage 2: Analysis of GNPs pretreatment using PEI for the 87 preparation of NR/EPDM filled GNPs nanocomposites
4.3.1 Selection of Dispersant for GNPs by Precipitation Studies 87
4.3.2 FTIR Analysis 91
4.3.3 XRD Analysis 95
4.3.4 Summary 97
4.4 Stage 3: Characterisation studies of NR/EPDM filled GNPs 98 Nanocomposites
4.4.1 Cure Characteristics 98
4.4.2 Tensile Strength 101
4.4.3 Hardness (Shore-A) 104
4.4.4 Swelling Behaviour 105
4.4.5 XRD Analysis 106
4.4.6 FESEM Observation 108
4.4.7 Summary 110
4.5 Stage 4: Thermal Behaviour of NR/EPDM filled GNPs 111 Nanocomposites
4.5.1 Heat Dissipation by Thermal Conductivity Analysis (TCA) 111 4.5.2 Heat Degradation by Thermogravimetric Analysis (TGA) 113 4.5.3 Dynamic Properties Analysis using Dynamic Mechanical
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LIST OF TABLES
TABLE TITLE PAGE
2.1 Classification of Nanofillers; Spherical, Nanotubes and Platelets
19
2.2 Principle Diene Monomer used in EPDM Manufacture 27 2.3 Levels of Sulphur and Accelerator in CV, SEV and EV 35
2.4 Vulcanisate Structures and Properties 35
2.5 Thermal Conductivities of Some Thermally Conductive Fillers
44
3.1 Specification of Purchased GNPs 49
3.2 Levels of Variables 50
3.3 24 Factorial Design Matrixes 51
3.4 The Typical Formulation for Preparation of NR/EPDM Compounds
52
3.5 The Formulation for Preparation of NR/EPDM Filled GNPs Nanocomposites
63
3.6 Fillers Loading 64
4.1 Regression Equations for Each Response Studied 71 4.2 Comparisons of Experimental and Predicted Tensile
Strength Values of NR/EPDM Blends
77
4.3 Criteria for Optimisation of Properties for Melt Blending of NR/EPDM Blends
80
4.4 Tg Values Obtained from DSC 84
PEI-viii
4.7 Thermal Conductivity Values of NR/EPDM Filled GNPs Nanocomposite Blends in respect of Different Blend System at Different Fillers Loading
ix
LIST OF FIGURES
FIGURE TITLE PAGE
2.1 Natural Rubber (Cis 1, 4-polyisoprene) 23
2.2 Polymeric Chain of Rubber 23
2.3 Main Synthetic Rubber Production System 25
2.4 EPM structure 26
2.5 Chemical structure of EPDM 26
2.6 Schematic models of network structure and entanglements in vulcanized and un-vulcanized NR
31
2.9 Crosslinking Characteristics of Elastomers Determined from the Torque Measurement
34
2.10 Schematic Illustration of GrapheneNanoplatelets. 36 2.11 Schematic for Particulates, Aggregate and Agglomerate 38 2.12 Graphene Sheets with Strong Covalent and Ionic Bonded
Atoms Held Together by Weak Van Der Waals Forces
38
2.13 Classification of Methods to Disperse Nanofillers in Polymer Resin
39
2.14 Schematic Diagram of the Microstructure of Graphene-Based Nanocomposites based on Monolayer and Trilayer Reinforcements
40
2.15 Schematic of Polymer Nanocomposites Achieving Exfoliation of Nanoplatelets in Polymers Continuous Phase by Assistance of Surface Treatment of Nanoplatelets
43
3.1 Flowchart of the Overall Experiment 46
3.2 The Main Materials used for the Preparation Of NR/EPDM Compounds
x
3.3 The Compounding Chemicals used for the Vulcanisation of the Rubber
3.6 NR/EPDM Blends Dumped from Internal Mixer 53
3.7 The Set Up for Gotech Hydraulic Hot Molding 55
3.8 The as-produced NR/EPDM Vulcanised Sheet after Hot and Cold Molding Operation
55
3.9 Dumbbell Shaped Test Piece 56
3.10 Zwick Roell Hardness Tester 56
3.11 GNPs Dispersion in Organic Solvent Solution 61 3.12 Ultrasonication-Mechanical Stirrer and Freeze Drying
Apparatus Set-Up for GNPs Surface Treatment Procedure
62
3.13 Thermal Conductivity Test Set-Up 67
4.1 3D Response Surface Model Graphs Depicting Variation in Scorch Time, Cure Time, Maximun Torque and Torque Difference as a Function of MAH Grafted EPM and Mixing Time
73
4.2 3D Response Surface Model Graphs Showing Variation in Tensile Strength, Modulus at 100% elongation, Modulus at 500% elongation and Elongation at Break
76
4.3 Plots of the Residuals Vs. Predicted Response for an Error Determination
78
4.4 3D Response Surface Model Graphs Representing Variation in Hardness as a Function of MAH Grafted EPM and Rotor Speed
79
4.5 The Swelling Percentage and Crosslink Density of the NR/EPDM Blends
81
4.6 DSC Thermograms for NR, EPDM, MAH grafted EPM, S0, S1 and S4
83
4.7 Scanning Electron Microscopy Micrographs Showing Tensile Fracture Surface of NR/EPDM Blends at 70/30
xi Blend Ratio
4.8 The GNPs Dispersion in Water and Five Organic Solvents Before Sonication, Dispersion Shortly after Tip Sonication and Dispersion 3 Weeks after Sonication.
89
4.9 TEM Images of GNPs Deposited from Ethanol and THF Suspension
90
4.10 FTIR Spectra of GNPs, PEI and PEI-Treated GNPs 92 4.11 A Schematic Represents the Attachment of PEI on GNPs
Surface
94
4.12 XRD Patterns of Pure GNPs and PEI-Treated GNPs 95 4.13 TEM Image PEI-Treated GNPs Shows Single Layer GNPs
and presence of PEI on the Edges of the GNPs Sheet
96
4.14 The effect of GNPs Loading on the Hardness of NR/EPDM Blends Filled with Pure GNPs and PEI-Treated GNPs
105
4.15 The Effect of GNPs Loading on the Swelling Percentages of NR/EPDM Blends Filled with Pure GNPs and PEI-Treated GNPs
106
4.16 X-ray Diffraction Pattern of Unfilled NR/EPDM blends, NR/EPDM Filled GNPs Nanocomposites and NR/EPDM Filled PEI-Treated GNPs Nanocomposites
107
4.17 Fractured Surface Morphology of Unfilled NR/EPDM Blends, NR/EPDM Blends Filled with 3.00 wt. % PEI-Treated GNPs, and NR/EPDM Blends Filled with 5.00 wt. % PEI-Treated GNPs
109
4.18 Thermal Conductivity Trends for NR/EPDM Filled GNPs Nanocomposite Blends in respect of Different Blend System at Different Fillers Loading
xii
4.22 Loss Modulus of Unfilled NR/EPDM Blends and NR/EPDM Filled GNPs Nanocomposites
118
4.23 Tan Delta of Unfilled NR/EPDM Blends and NR/EPDM Filled GNPs Nanocomposites
xiii
LIST OF APPENDICES
APPENDIX TITLE PAGE
A Sample of Calculations 135
xiv
LIST OF ABBREVIATIONS AND SYMBOLS
°C - Degree celsius
2D - Two dimensional
6PPD - N-(1,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine ANOVA - Analysis of variance
ASTM - American standard testing of materials ATR-FTIR - Attenuated total reflactance-FTIR
CNF - Carbon nanofiber
CNTs - Carbon nanotubes
CO2 - Carbon dioxide
CRI - Cure rate index
DCP - Dicumyl peroxide
DMA - Dynamic mechanical analysis DSC - Differential scanning calorimetry DTG - Derivative thermal gravimetry
E′ - Storage modulus
E′′ - Loss modulus
EB - Elongation at break
EPDM - Ethylene propylene diene monomer EPM - Ethylene propylene copolymer FEA - Finite element analysis
FESEM - Field emission scanning electron microscopy FWHM - Full width at half maximum
GNPs - Graphene nanoplatelets
GPa - Gigapascal
M100 - Modulus at 100% elongation M300 - Modulus at 300% elongation M500 - Modulus at 500% elongation
MAH - Maleic anhydride
xv
Mc - Average molecular weight between crosslink MH-ML - Torque difference
MH - Maximum torque
ML - Minimum torque
MMT - Montmorillonite
Mn - Average number molecule
Mw - Average weight molecule
nm - Nanometer
NR - Natural rubber
NR/EPDM - Natural rubber/ ethylene propylene diene monomer
OH - Hidroxyl
PEI - Polyethyleneimine
PEI-treated GNPs - GNPs treated with polyethyleneimine
phr - Per hundred rubber
PVA - Polyvinyl acetate
RSM - Response surface methodology TMTD - Tetramethylthiuramdisulfide
Qm - Weight increase
υo - Molar volume of toluene
υr - Volume fraction of rubber in swollen sample
xvi
LIST OF PUBLICATIONS
Journal
1. Jeefferie Abd Razak, Sahrim Haji Ahmad, Chantara Thevy Ratnam, Mazlin Aida
Mahamood, and Noraiham Mohamad. "Effects of poly (ethyleneimine) adsorption
on grapheme nanoplatelets to the properties of NR/EPDM rubber blend nanocomposites". Journal of Materials Science, 50, no. 19 (2015): 6365-6381.
2. Jeefferie Abd Razak, Sahrim Haji Ahmad, Chantara Thevy Ratnam, Mazlin Aida
Mahamood, Juliana Yaakub, and Noraiham Mohamad (2015), Effects of EPDM-g
-MAH compatibilizer and internal mixer processing parameters on the properties of NR/EPDM blends: An analysis using response surface methodology. J. Appl. Polym. Sci., 132, 42199.
3. J. Abd Razak, S. H. Ahmad, C. Thevy Ratnam, M. A. Mahamood, K. T. Lau, H. E. Ab Maulod, R. F. Munawar, N. Mohamad, "Non-Covalent Polymeric Wrapping of IGEPAL C0890 for Graphene Nanoplatelets (GNPs-C0890) Filled NR/EPDM Rubber Blend Nanocomposites", Applied Mechanics and Materials, Vol. 761, pp. 385-390, May. 2015.
4. N. Mohamad, M. A. Mahamood, J. Abd Razak, R. F. Munawar, M. Z. Zainal Abidin, M. A. Azam, M. S. Kasim, M. S. Othman, M. I. Shueb, "Cure Characteristics of Natural Rubber/EPDM Blends for the Effect of MAH Grafted EPM and Compounding Parameters via Response Surface Methodology", Applied Mechanics and Materials, Vol. 761, pp. 441-446, May. 2015.
xvii
6. N. Mohamad, M. A. Mahamood, Y. Juliana, A. R. Jeefferie, A. Muchtar, M. I. Shueb, M. S. Kassim, M. A. Azam, Y. M. Yuhazri, N. Mustafa, A. R. Toibah, T. R. Sahroni, and Q. Ahsan. "Functionalisation of ethylene–propylene copolymer by melt grafting of maleic anhydride using a high shear internal mixer". Materials Research Innovations. 2014; 18(S6), S6-36-S6-42.
7. The Effects of Covalent Treated Graphene Nanoplatelets Surface Modification to Cure Characteristic, Mechanical, Physical and Morphological Properties of NR/EPDM Rubber Blend Nanocomposites, 2014. JA Razak, SH Ahmad, CT Ratnam, MI Shueb, MA Mahamood, J Yaakub, Advances in Environmental Biology 8 (8), 3289-3298.
8. NR/EPDM elastomeric rubber blends miscibility evaluation by two-level fractional factorial design of experiment. Razak, Jeefferie Abd and Ahmad, Sahrim Haji and Ratnam, Chantara Thevy and Mahamood, Mazlin Aida and Yaakub, Juliana and Mohamad, Noraiham, AIP Conference Proceedings, 1614, 82-89 (2014), DOI:http://dx.doi.org/10.1063/1.4895176.
Conference
1. N. Mohamad, M. A. Mahamood, J. Abd Razak, R. F. Munawar, M. Z. Zainal Abidin, M. A. Azam, M. S. Kasim, M. S. Othman, M. I. Shueb, 2013. Cure Characteristics of Natural Rubber/EPDM Blends for the Effect of MAH grafted EPM and Compounding Parameters via Response Surface Methodology. 3rd
International Conference on Design and Concurrent Engineering 2014, 22 and 23 September 2014.
2. N. Mohamad, M. A. Mahamood, Y. Juliana, A. R. Jeefferie, A. Muchtar, M. I. Shueb, M. S.Kassim, M. A. Azam, Y. M. Yuhazri, N. Mustafa, A. R. Toibah, T. R. Sahroni and Q. Ahsan., 2013. Functionalisation of ethylene–propylene copolymer by melt grafting of maleic anhydride using a high shear internal mixer.
1 CHAPTER 1
INTRODUCTION
1.1 Research Background
The emergence of nanomaterials in the area of polymer science and technology have caused nanosized materials to be widely employed in advanced composite systems (Arroyo et al., 2007; Sookyung et al., 2014). The dimension of one of the constituent phase in the composites sometimes can be between 1 to 100 nm, and under these atomic dimensions that particular phase has properties rather different from those of the same material in the bulk form and are referred to as ‗‗nanocomposite‘‘ (Olad, 2011).
