Papers by Author: Eiichi Sakai

Abstract: Multiwalled carbon nanotubes/Polycarbonate (MWCNTs/PC) nanocomposites were successfully prepared by melting mixing. With the injection speed and temperature changed, different MWCNTs contents MWCNTs/ PC composites were prepared. The electrical conductivity of nanocomposites was compared with different injection speeds and injection temperatures. It was found that the electrical conductivity of the MWCNTs/PC nanocomposites was decreased with MWNTs content increasing, and were both affected by the injection speed and temperature. Besides, at the vicinity of the surface of samples, the resistivity of MWCNTs/PC nanocomposites was the maximum; the closer to the samples inner, the resistivity was smaller and more stabilized. The microstructure and morphology of composites were analyzed by Scanning Electron Microscopy (SEM) techniques, and the MWCNTs’ dispersion in PC matrix and the interfacial interaction between MWCNTs and PC were analyzed.

Abstract: The melting mixing was applied in the preparation of Multiwalled carbon nanotubes/Polycarbonate (MWCNTs/PC) nanocomposites. MWCNTs/PC nanocomposites with different MWCNTs contents were prepared under different injection conditions. The mechanical property of nanocomposites was comparatively investigated. The results demonstrated that: the tensile property of the nanocomposites was slightly improved by MWCNTs content increasing; but as the MWCNTs contents went on to increase to 10wt%, the tensile strength and bending strength were obviously decreased about 35% and 47%, respectively, but the impact strength and hardness were increased. The center hardness of MWCNTs/PC nanocomposites was greater than the surface hardness. Besides, the changes on the mechanical properties of the nanocomposites were studies by changing the injection conditions. By Scanning Electron Microscopy (SEM) observation, the microstructure and morphology of nanocomposites were analyzed, revealing that the center of the nanocomposite distributed more MWNTs, and the injection conditions would affect the MWNTs’ dispersion in the matrix and the interfacial interaction between MWCNTs and PC.

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 biodegradable composites were prepared with the oyster shell particles (OSP) and poly(lactic acid)(PLA) by injection molding. The mechanical and thermal properties were investigated. The degradation temperature of the composites decreased by increasing the content of OSP compared with PLA. From the results of tensile test, the tensile strength and the fracture strain of the composites decreased because of exist of OSP. However, the Young’s moduli of the composites increased compared with PLA. The SEM observation of morphology confirmed that the interface between PLA and OSP had poor adhesion.

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.

Abstract: To consider the effective utilization of plastics and agricultural wastes, rice straw fibre was extracted from agricultural wastes, and then composited with polylactic acid(PLA). The thermal stability of straw/poly(lactic acid)(straw/PLA) composites decreased (Thermogravimetric Analysis, TGA). Tensile strength, fracture strain and sharply impact strength of straw/PLA were decreased with the increase of filler content and grain size of straw. Yong’s modulus were increased as the increasing of straw content.

Abstract: Graphene-poly(methyl methacrylate) (GNS-PMMA) composites were prepared by two methods. Graphite oxide nanosheet-poly(methyl methacrylate) (GO-PMMA) composites were prepared of methyl methacrylate monomer and the presence of graphite oxide (GO). Then the GO-PMMA composites were reduced to graphene nanosheet-poly(methyl methacrylate) by using hydrazine hydrate. The obtained composites were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). The composite exhibited conductivities in the 1.58×10^-9-4.21 S/cm range, depending on the amounts of graphite oxide and PMMA.