아민 기능화 다중벽 탄소나노튜브가 포함된 에폭시 나노복합재의 경화 거동 및 특성 = Curing Behavior and Properties of Epoxy Nanocomposites with Amine Functionalized Multi-Wall Carbon Nanotubes

다국어 초록 (Multilingual Abstract)

To take full advantage of carbon nanotubes (CNTs) as reinforcing materials, homogeneous dispersion and strong interfacial bonding are essential. Therefore, in this study, amine functionalization of multi-wall carbon nanotubes (MWNTs) was performed via treating pristine MWNTs with 4-aminobenzoic acid in polyphosphoric acid. The functionalization was confirmed by Fourier transform infrared spectrophotometer (FTIR) and thermo-gravimetric analyzer (TGA). Using the functionalized MWNTs, epoxy/MWNT nanocomposites were prepared, and their curing behavior and physical properties were investigated. Differential scanning calorimeter (DSC) was used to obtain experimental kinetic data for curing kinetic analysis. The functionalized MWNTs accelerated the curing rate of the nanocomposite system. An autocatalytic reaction mechanism could describe adequately the curing kinetics of the epoxy/MWNT nanocomposite system. The kinetic parameters were determined by fitting the DSC conversion data to the kinetic equation using the Marquardt's multivariable nonlinear regression and Runge-Kutta integration techniques. The functionalization induced strong interfacial bonding between the epoxy matrix and the MWNTs, and resulted in considerable improvements in the properties of the nanocomposites. Fracture surfaces of the nanocomposites were investigated by scanning electron microscopy (SEM).

국문 초록 (Abstract)

탄소나노튜브가 갖는 낮은 분산 안정성과 결합력의 한계를 극복하기 위하여 탄소나노튜브를 표면개질 시키고 FT-IR과 TGA, SEM을 이용하여 이를 확인하였다. 표면개질된 탄소나노튜브를 이용하여 나노복합재료를 제조하고 경화거동 및 특성을 조사하였다. 경화거동은 DSC를 이용하여 조사하였고, 표면개질된 탄소나노튜브의 함량이 증가할수록 반응 속도는 증가하였다. 반응속도식의 parameters들은 DSC 전환율 데이터로부터 multivariable nonlinear regression과 intergration techniques을 이용하여 결정하였다. UTM을 이용하여 나노복합재료의 굴곡강도를 측정하고, 파괴단면을 SEM으로 조사하였다. TMA를 이용하여 나노복합재료의 열팽창계수 및 유리전이온도를 측정하였고, DMA를 이용하여 물리적 성질을 측정하였다. 이와 같은 열적, 물리적 특성의 측정을 통하여 개질된 탄소나노튜브 표면의 amine group이 수지와의 결합력 및 분산 안정성을 높여 물성 향상에 기여하는 것을 확인할 수 있었다.

목차 (Table of Contents)

• Ⅰ. INTRODUCTION 1
• Ⅱ. EXPERIMENTAL 8
• 2.1 Materials 8
• 2.2 Functionalization of MWNTs 8
• 2.3 Preparation of Epoxy/MWNT Nanocomposites 10
• 2.4 Measurements 10
• 2.4.1 Fourier Transfer Infrared Spectrophotometer (FT-IR)
• 2.4.2 Differential Scanning Calorimeter (DSC)
• 2.4.3 Thermo-gravimetric Analyzer (TGA)
• 2.4.4 Dynamic Mechanical Analyzer (DMA)
• 2.4.5 Thermal Mechanical Analyzer (TMA)
• 2.4.6 Field Emission Scanning Electronic Microscope (FE-SEM)
• 2.4.7 Universal Testing Machine (UTM)
• Ⅲ. RESULTS AND DISCUSSION 14
• 3.1 Characterization of Functionalized MWNTs 14
• 3.2 Reaction Kinetics 16
• 3.3 Thermal and Mechanical Properties 25
• 3.4 Structure and Morphology 35
• Ⅳ. CONCLUSIONS 38
• REFERENCES 39