Papers by Author: Takuya Murata

Abstract: In this work, the spring back, dimensional change, internal structure and morphology of extruded polypropylene were investigated in order to consider the rolling characteristic. It was found that the internal structure, molecular orientation and crystallinity were changed a little by high spring back under low reduction in thickness. Crystal structure was extended along the rolling direction with high reduction in thickness due to the increase of plastic deformation. As a result, molecular orientation increased and crystallinity decreased at over 30% of reduction in thickness. Crystalline structure of surface was similar to the center part in cross-section at 70% reduction in thickness, and molecular orientation was constant.

Abstract: The present work investigated the variation of internal structure, molecular orientation, crystallinity and mechanical characteristics of polypropylene(PP) after rolling process. The materials plate became narrow when rolled from entrance to exit, and the internal crystalline gradually deformed and at last destroyed. Plastic deformation was discovered along the rolling direction. In this direction, the crystallinity and vickers hardness were decreased, and molecular orientation was increased. Moreover, molecular orientation had a sharp increase at the second half part of rolling sample. The tensile stress of rolled samples increased by 80% parallel to rolling direction and decreased by 22% perpendicular to rolling direction.

Abstract: To consider the effective utilization of agricultural wastes, rice straw/Poly (lactic acid) (PLA) composites were prepared by the mechanically compounding and injection molding. The water contents were increased with increasing the rice straw content. After natural weathering or burial in soil, more microcracks were observed on the surface of the PLA composites rather than the pure PLA. Moreover the tensile strength and the fracture strain of PLA composites were obviously decreased with increasing the weathering and burial testing term.