PET container wastes in Japan are rapidly increasing since the establishment of the container waste recycling law. Although most of PET container waste recycling in Japan uses the melt-recycling method, new feedstock recycling methods are expected because the supply of melt-recycled resin will be much greater than the demand of plastic goods made from melt-recycled resin. New physical recycling methods by material compounding will be more important because they will bring new added value. We evaluated these methods from an economics viewpoint by determining the break even point using a profit and loss model. In this model, the amount of PET bottles recycled in ten years is estimated to be about 30∼37kt per year. This model predicts that methods leading to an added value of 40 yen per kg will bring 12 billion yen social benefit per year.

抄録全体を表示

Recently, the utilization of plastic composites containing natural products which are more environmentally friendly is gaining popularity. These composites can drastically reduce raw material costs while recycling natural waste products such as flocks. In this study, composites of biodegradable resins with natural products such as waste cotton fiber, recycled paper, jute fiber and granulated starch were examined experimentally for their mechanical properties.
The biodegradable resins, PCL and PBS, were grafted with maleic anhydride in order to increase the in compatibility with natural products. The kneading of these biodegradable resins with natural product additives was carried out using a segmental twin screw extruder.
Tensile, three-point bending and Izod impact tests were carried out. There was an improvement in the material strength characteristics in the tensile and three-point bending response to an addition of natural products in all the composites tested.
The tensile and bending strength greatly dependent on the aspect ratio of the additives. Waste cotton fiber, with the highest aspect ratio showed the largest values. The Izod impact value of all composites tested however decreased.
For the tensile modulus for the composites, it was shown that the complex rule of Kerner could be applied for the composites with aspect ratio under 40. In addition, it was clarified that the heat-resistance of the waste cotton composite was the greatest of all the tested composites.

抄録全体を表示

This paper presents a study on injection molded protein fiber reinforced biodegradable composites. Raw silk fiber and polybutylene succinate (PBS) were used as reinforcement and matrix material respectively. The mechanical properties of theses silk/PBS composites and the flow patterns of silk fibers in the molded composites were investigated. Tensile, flexural and Izod impact tests were carried out and the fracture surfaces were observed using SEM. In order to observe the flow patterns of silk fibers in the molded composite, an etching treatment was performed on the surface of the silk/PBS composites using chloroform. The tensile, flexural and Izod impact properties increased with increasing silk fiber volume fraction. The short silk fibers were tangled throughout most of the composite except in the skin layer. In addition, good adhesion was seen in the interface between silk fiber and PBS resin. It is concluded here that the silk fiber can be effectively used as a reinforcement for biodegradable composites.

抄録全体を表示

GPC and rheological measurements under shear and uniaxial flow for Poly (L-lactic acid) modified by dicumyl peroxide were carried out. The description of experimental GPC resulted that some amounts of added dicumyl peroxide caused an increase of cross-linked regions in the polymer. The viscoelastic properties of poly (L-lactic acid) modified by dicumyl peroxide under the shear flow were investigated. It was found that the rheological properties of the poly (L-lactic acid) were distinctly different from those of a neat poly (L-lactic acid). The elastic response at low frequencies was significantly enhanced in comparison with the neat poly (L-lactic acid). Uniaxial elongation behavior was also measured. In short time region, the elongational viscosity of Poly (L-lactic acid) modified by dicumyl peroxide were three times larger than the shear viscosity. This result meant that Trouton's rule is applicable to the results. Beyond a certain critical strain, the uniaxial elongational viscosity showed rapid increase, which was referred to as strain hardening. Die-swell ratio increased with dicumyl peroxide contents. Furthermore poly (L-lactic acid) modified by dicumyl peroxide was molded by direct-blow. The thickness distribution could be homogeneous by modified peroxide.

抄録全体を表示

Recently, plastic mass disposal is taken up as large environmental problem, and the utilization of biodegradable plastic is noticed as one of the problem solution. However, the material properties of biodegradable plastic are inferior to general commodity plastics and its unit price is high, and there are many problems to be solved on the utilization extension. In this report, the clay composite of biodegradable resin, in which organic montmorillonite clay (OMTS) was filled, was experimentally produced. The material property modification of the clay nanocomposite of biodegradable resin was examined. PCL and PBS biodegradable resins were grafted using the maleic anhydride in order to increase the compatibility with the clay. For the material strength test, tensile test, three-point bending test and Izod impact test were carried out. There was an improvement of material strength for the composite in tensile test and three-point bending test. For Izod impact test, however, the material strength of the composite depended on the resin tested and clay concentration. For PBS clay composite, the impact strength increased with OMTS addition. From wide angle X-ray diffraction measurement on the composite, it was found that the crystallization of the composite increased with the addition of OMTS. On thermal decomposition test of the composite, it was shown that the thermal stability of the composite was increased. In addition, the clay nanocomposite foams were produced from the viewpoint of the material cost reduction and it was shown that the bending stress of the composite foams was increased.

抄録全体を表示