냉각속도가 유리섬유 강화 열가소성 복합재의 기계적 물성에 끼치는 영향

Abstract

폴리머 기반의 복합재를 생산함에 있어서 복합재의 생산성 및 효율 향상을 위해서 가장 중요한 것은 공정 조건 확립이다. 기존의 열경화성 수지 기반의 복합의 경우 공정 조건 연구가 활발히 이루어진 반면에 열가소성 복합재의 경우 공정조건 중 온도가 복합재의 물성에 미치는 영향에 대해서는 충분한 연구가 이루어지지 않았다. 따라서 본 연구에서는 유리섬유/ 폴리프로필렌 (GF/PP) 복합재에 인장, 파괴인성, 층간전단강도, 충격시험을 실시하여 공정 조건 중 중요한 요소인 냉각속도가 복합재의 기계적 물성에 끼치는 영향을 확인하였다. X선 회절 분석 (XRD)과 시차주사열량측정법(DSC) 은 폴리프로 필렌의 냉각속도의 변화에 따른 결정화도를 측정하기 위하여 실시하였다. 실험 결과를 통하여 폴리프로필렌의 낮은 결정화도가 유리섬유와 폴리프로 필렌 사이의 계면강도를 증가시켜 약 15%의 인장강도를 향상시키는 것을 확인할 수 있었고, 반면에 폴리프로필렌의 높은 결정화도가 폴리프로필렌 결정 간의 접합력을 증가시켜 2배 이상의 파괴인성, 20% 이상의 층간전단강도, 그리고 20% 이상의 충격특성을 향상시킨다는 것을 확인할 수 있었다.|For the production of polymer-based composite materials, in depth understanding of appropriate manufacturing processes is important to improve productivity and the fabrication process. However, the effect of the temperature profile on the mechanical properties of thermoplastic composite materials is still not well understood although manufacturing systems for thermosetting composite materials have been developed in many ways. In this study, the effect of the cooling rate on the mechanical properties of glass fiber (GF)/polypropylene (PP) composite was investigated including the tensile, interlaminar shear strength, fracture toughness and also the impact properties. The X-ray diffraction (XRD) and the differential scanning calorimetry (DSC) analysis were used to observe the crystallinity of the matrix. Based on these results, it was achieved that low crystallinity of PP enhances 15% of the tensile strength of GF/PP due to the sufficient interfacial strength between GF and PP. On the other hand, high crystallinity of PP improves about more than 2 times of fracture toughness in all mode mixtures, 20% of interlaminar shear strength and 20% of impact properties due to the increased adhesive strength between PP spherulite.; For the production of polymer-based composite materials, in depth understanding of appropriate manufacturing processes is important to improve productivity and the fabrication process. However, the effect of the temperature profile on the mechanical properties of thermoplastic composite materials is still not well understood although manufacturing systems for thermosetting composite materials have been developed in many ways. In this study, the effect of the cooling rate on the mechanical properties of glass fiber (GF)/polypropylene (PP) composite was investigated including the tensile, interlaminar shear strength, fracture toughness and also the impact properties. The X-ray diffraction (XRD) and the differential scanning calorimetry (DSC) analysis were used to observe the crystallinity of the matrix. Based on these results, it was achieved that low crystallinity of PP enhances 15% of the tensile strength of GF/PP due to the sufficient interfacial strength between GF and PP. On the other hand, high crystallinity of PP improves about more than 2 times of fracture toughness in all mode mixtures, 20% of interlaminar shear strength and 20% of impact properties due to the increased adhesive strength between PP spherulite.