PET fiber reinforced PE thermoplastic composites were molded by using industrial wastes of PET/PE core/sheath non-woven fabrics. The waste fabrics were fed directly into the injection molding machine without prior pelletizing to simplify the molding process. The composition of the fabrics used was 50% PET and 50% PE. By controlling the molding temperature, the PE portion of the fabric could be melted while keeping the PET fibers intact during the injection molding process. At a molding temperature of 200°C, the tensile, bending and impact behavior of the molded composites were much higher than those of the neat PE matrix. Reasonably high Izod impact values were also obtained for the molded composites. However, both the strength and modulus decreased with increasing molding temperature because of the thermal damage to the PET fibers at higher temperatures. The molding system discussed in this paper shows promise for contributing toward the material recycle of core/sheath fiber wastes as a raw material of thermoplastic composites.

抄録全体を表示

In this study, the effects of glass fiber orientation on mechanical properties of compression molded sheet molding compounds (SMC) were examined. The charge pattern is an important factor affecting the glass fiber orientation and distribution in the final molded part. Three different charge patterns were adopted for the purpose of examining the influence of the glass fiber orientation on mechanical properties of molded SMC. Soft X-ray photography was used for examining the glass fiber orientation. Bending modulus and coefficient of thermal expansion at various locations of the SMC molding were also evaluated.
The glass fiber orientation and distribution caused anisotropies in the mechanical properties of the SMC. The use of a smaller charge pattern increased the variation in the bending modulus and coefficient of thermal expansion across the sample because of greater induced fiber distribution and orientation effects.

抄録全体を表示

Although V-notches at weldlines in injection moldings are regarded as the causes of the reduction of mechanical properties and visual defects, few researchers have investigated the role of V-notches in the fracture behavior of weldlines. The fracture behavior of an adjacent flow weldline occurring behind an obstructive pin in injection-molded polystyrene plates was investigated by a fracture test which followed the technique of the double torsion test. The behavior of crack propagation was quite different between the upstream side and the downstream side of the weldline. There was a distinct boundary point between the sides. We defined the length of the upstream side as weldline length of fracture, L_wf. The crack propagated first in the sub-layer below the V-notch along the weldline and second inwardly from the sub-layer within L_wf. On the other hand, the crack at the sub-layer and that at the inward part propagated simultaneously in the area beyond L_wf similar to non-weld specimens. The fracture behavior had a close relationship to the V-notch shape. The V-notch depth showed little change within L_wf, while the depth decreased drastically in the area beyond L_wf. This relationship suggested that the difference of the fracture behavior was caused by the degree of molecular entanglement at the sub-layer below the V-notch.

抄録全体を表示