비균질 나노복합재료의 열적특성 및 변형거동 연구

Abstract

탄소나노튜브(Cabon Nano Tube, CNT)는 높은 세장비와 뛰어난 기계적 성질, 열전달 및 전기적 특성 등으로 인해 기존 복합재의 한계를 극복할 수 있는 강화재 및 필러(filler)로써 각광받고 있다. 그러나 이와 같은 장점을 효과적으로 발현하기 위해서는 기지재료 내 CNT의 균질한 분산이 매우 중요한 요소이다. 본 논문은 CNT 분산도에 따른 CNT 기반 나노복합재료의 열적특성 및 변형거동에 관한 연구로서 첫째, 재료 비균질도 (Heterogeneity factor, HF)를 이용한 나노복합재료 내 CNT 분산도의 정량적 평가, 둘째, 기계적, 열적 물성과 HF간의 관계 규명 및 셋째, 재료의 비균질 미시구조에 따른 역학적 변형거동 고찰에 관한 것으로 구분할 수 있다. 공정변수 조절을 통해 CNT의 분산도가 서로 다른 비균질 나노복합재료를 제조하였으며, 미시구조 사진의 디지털 이미지 분석을 기반으로 CNT응집체의 분포함수를 도출하였고 이를 바탕으로 HF를 산출, 재료의 비균질성을 평가할 수 있었다. 또한 열전도율시험 및 인장시험을 통해 재료의 열적, 기계적 물성과 HF의 상관관계를 분석하였다. 아울러 미시구조분석을 통해 재료의 비균질성이 역학적 변형거동에 미치는 영향을 고찰하였다.| Carbon nanotube(CNT) has been highly favoured as the most promising material for reinforcement and/or filler of nanocomposites due to the significantly high aspect ratio, outstanding mechanical properties, together with excellent heat transfer and electrical characteristics. The uniform dispersion of CNT, however, is the very essential factor to exploit effectively its advantages. In this thesis, thermal characteristics and deformation behaviors of CNT nanocomposites in accordance with the degree of dispersion of CNT were studied. Herein, firstly, a quantitative evaluation of the degree of dispersion in CNT nanocomposites by using Heterogeneity factor(HF) was conducted. Secondly, the relationships between mechanical and thermal properties with HF were identified. Finally, the mechanical deformation behaviors according to the heterogeneous microstructure of CNT were investigated. Heterogeneous nanocomposites having a different degree of dispersion in CNT were developed by the change of process parameters, and hence the distribution functions of CNT agglomerates were deducted based on the digital image processing technique of the microstructures. Therefore, HF was determined for the assessment of heterogeneity of the CNT nanocomposites. In addition, the correlation between thermal and mechanical properties with HF was analysed through the thermal conductivity measurement test and the uniaxial tensile test of the materials. Furthermore, the influence of heterogeneity on mechanical deformation behavior of CNT nanocomposites was investigated by means of the analysis of microstructures.; Carbon nanotube(CNT) has been highly favoured as the most promising material for reinforcement and/or filler of nanocomposites due to the significantly high aspect ratio, outstanding mechanical properties, together with excellent heat transfer and electrical characteristics. The uniform dispersion of CNT, however, is the very essential factor to exploit effectively its advantages. In this thesis, thermal characteristics and deformation behaviors of CNT nanocomposites in accordance with the degree of dispersion of CNT were studied. Herein, firstly, a quantitative evaluation of the degree of dispersion in CNT nanocomposites by using Heterogeneity factor(HF) was conducted. Secondly, the relationships between mechanical and thermal properties with HF were identified. Finally, the mechanical deformation behaviors according to the heterogeneous microstructure of CNT were investigated. Heterogeneous nanocomposites having a different degree of dispersion in CNT were developed by the change of process parameters, and hence the distribution functions of CNT agglomerates were deducted based on the digital image processing technique of the microstructures. Therefore, HF was determined for the assessment of heterogeneity of the CNT nanocomposites. In addition, the correlation between thermal and mechanical properties with HF was analysed through the thermal conductivity measurement test and the uniaxial tensile test of the materials. Furthermore, the influence of heterogeneity on mechanical deformation behavior of CNT nanocomposites was investigated by means of the analysis of microstructures.