단섬유강화 폴리프로필렌 복합재의 환경온도변화에 따른 파괴강도특성에 관한 연구

A Study on Environmental Strength Properties Fracture of Short Fiber Reinforced Polypropylene

In this paper, the fracture mechanism and the properties of microscopic structure of glass fiber reinforced plastics produced by shouting machine was investigated by universal testing instrument and SEM in varied environment temperature. 1) The tensile strength decreased with an increase of environment temperature. The above trend was more dominant in the parent specimen than in the weld specimen. 2) When environment temperature changing, the changing of tensile strength in parent is higher than that of weld part, because it is much influenced by fiber compared to matrix. The strength decrease in welding point is much influenced by fiber direction than composition condition as V-notch in weld line. 3) The fracture surface observation by SEM at low temperature(-30℃) showed fiber breaks in the matrix. But at high temperature(80℃), some of fibers were ruptured but some were delaminate with plastic deformation in the matrix. The tensile strength was higher at low temperature than at high temperature, which was believed to be due to the difference in binding force between matrix and fiber.