短繊維強化ポリエチレンテレフタレートの微視構造ならびに破壊機構に対する繊維径の効果

抄録

Uniaxial tensile deformation and fracture behavior of injection-molded, short-glass-fiberreinforced poly (ethylene terephthalate) were investigated with special attention to the effects of fiber diameters (d=6, 10, 16, 23.μm). Influence of fiber surface treatment was also studied. Fiber aspect ratio and fiber number density were measured. Those values exhibited a decrease in average with an increase of fiber diameter. Sizing and silane treatment of fibers resulted in a slight increase of average aspect ratio when compared with a case of etching treatment. A microscopic failure morphology observation during loading to the maximum stress level showed shear banding around fiber ends, debonding and voiding at fiber ends and fiber breakage. Values of the minimum fiber length lmin were presented for fibers of different diameters. Below lmin, failure was hardly observed. In a process of load increase, failure sites joined together in a few local regions to generate catastrophic fracture. The failure processes were similar in specimens with fibers of different d, irrespective of the fiber treatment. Furthermore, critical aspect ratio was measured with average length of broken fibers to estimate the fibermatrix interfacial shear strength.