Preparation and Mechanical Property of Butyl Rubber Nanocomposites with Modified Graphene Oxide and Silica = 개질된 그래핀옥사이드 혹은 실리카와 부틸고무 나노복합재료 제조 및 물리적 특성

다국어 초록 (Multilingual Abstract)

Graphene is an effective nanofiller for the manufacture of rubber nanocomposites with improved physical, mechanical and electrical properties. However, the hydrophilic surface of graphene oxide(GO) as a reinforcement in the rubber matrix makes it difficult to disperse in the hydrophobic rubber matrix. Therefore, it is an important issue to improve the compatibility of the GO sheet with the rubber matrix. Silica has limited applications due to poor compatibility between rubber matrix and severe agglomeration due to the surface hydroxyl groups of silica. Therefore, improving the compatibility and dispersibility with the rubber matrix through surface modification of silica is a very important factor. In the first chapter, butyl rubber/hydrophobized graphene oxide (HG) nanocomposites were prepared by solution mixing followed by compression molding process, and their properties were evaluated using scanning electron microscope, oscillating disc rheometer, universal testing machine, thermogravimetric analysis, and diferential scanning calorimetry. The hydrophilic graphene oxide obtained through the oxidation of graphite was frst hydrophobized with octadecylamine. The HG exhibit excellent dispersibility in toluene and stable under stationary condition for over 30 days. The chemical structure and functionality of HG was analyzed by fourier transform infrared, raman spectroscopies, and wide-angle X-ray difraction. HG was successfully dispersed within butyl rubber matrix and result in significant reduction of curing time (around 30%), enhanced tensile strength (around 35%) as compared to the pristine butyl rubber. The air permeability of the hydrophobized graphene oxide composites was also signifcantly reduced by 75% compared to unflled butyl rubber. In the second chapter, butyl rubber/HG nanocomposites were prepared via shear-induced compounding. Butyl rubber/HG nanocomposites were prepared by thermal vulcanization process through compression molding. The HG was dispersed at the nanostructure within butyl rubber matrix, and the resulting nanocomposites had significantly reduced curing time(around 50%). The overall tensile properties were marginally enhanced. In the third chapter, butyl rubber was reinforced by the isoprene-modified silica. The modified silica was prepared via chemical modification by a hydrophobic and reactive oligomeric liquid isoprene rubber in a solvent. Thereafter butyl rubber was compounded with the modified silica and vulcanized by thermal compression molding process. The surface modification of the silica moved up the curing time and maginally increased tensile strength and modulus of the rubber composites. The theological model by the Smallwood and Guth and Gold equation proposed that the spherical filler particles are aggregated with increasing the loaded amount of the silica filler and results in a change from a spherical to a non-spherical shape. The best fitting for the experimental data at the higher volume fractions than 0.12 was obtained by using the Guth and Gold Equation with a shape factor of 2.5.
In conclusion, the surface energy of the graphene based fillers and its structure in the composites are responsible for the enhanced properties. The vulcanization condition and mechanical properties of the graphene based butyl rubber nanocomposites were significantly dependent on the nanostructure of fillers and the compatibility between filler and butyl rubber. The properties of the graphene based nanocomposites can be controlled by the nanostructure and surface properties of the fillers which may be suitable as future advanced polymeric materials. The properties of the silica/butyl rubber composites can be controlled by chemical modification of the silica surface using isoprene rubber molecules which can be alternative to use in various advanced polymeric materials.

목차 (Table of Contents)

• Ⅰ. Introduction 1
• Ⅱ. Objective of This Dissertation 6
• Ⅲ. Theoretical Background 9
• 1. Modified graphene oxide and silica/butyl rubber nanocomposites 9
• 1.1. Polymer nanocomposites 9
• 1.2. Graphene and Graphene oxide 20
• 1.3. Modified silica 40
• 1.4. Vulcanized butyl rubber nanocomposites 53
• Ⅳ. Hydrophobized Graphene Oxide/Butyl Rubber Nanocomposites via Solution Process 75
• 1. Introduction 75
• 2. Experimental 77
• 2.1. Materials 77
• 2.2. Synthesis of hydrophobized GO 77
• 2.3. Preparation of HG/BR nanocomposites 77
• 2.4. Characterization 78
• 3. Results and Discussion 82
• 3.1. Storage stability of HG 82
• 3.2. Preparation of GP, GO, and HG 82
• 3.3. Properties of BR nanocomposites with GP, GO, and HG 83
• 4. Conclusions 98
• 5. References 99
• Ⅴ. Modified Graphene Oxide/Butyl Rubber Nanocomposites by Shear Mixing Process 102
• 1. Introduction 102
• 2. Experimental 104
• 2.1. Materials 104
• 2.2. Synthesis of GO and HG 104
• 2.3. Preparation of HG/BR nanocomposites by shear mixing process 104
• 2.4. Characterization 105
• 3. Results and Discussion 106
• 3.1. Characterization of modified graphene oxide 106
• 3.2. Vulcanization characteristics of butyl rubber nanocomposites 107
• 3.3. Mechanical properties of the nanocomposites 108
• 3.4. Thermal properties of the nanocomposites 109
• 4. Conclusions 119
• 5. References 120
• Ⅵ. Isoprene Modified Silica Reinforced Butyl Rubber Nanocomposites 122
• 1. Introduction 122
• 2. Experimental 124
• 2.1. Materials 124
• 2.2. Surface modification of silica with a rubber modifier 124
• 2.3. Preparation of butyl rubber/IMNS vulcanized nanocomposites 125
• 2.4. Characterization 125
• 3. Results and Discussion 127
• 3.1. Modification of the silica particles with the liquid rubber 127
• 3.2. Vulcanization kinetics of the rubber nanocomposites 127
• 3.3. Dynamic mechanical behavior of the nanocomposites 129
• 3.4. Tensile properties of the nanocomposites 130
• 4. Conclusions 145
• 5. References 146
• Ⅶ. Summary (Korean) 148
• List of Publication 150