ポリスチレンの破壊におよぼす温度およびひずみ速度の影響

抄録

Effects of temperature and strain speed on the fracture formation of polystyrene have been studied in terms of the fracture surface morphology and the mechanical property. Elongation of polystyrene indicates the minimum point at 40_??_70°C. That point is in accord with the temperature at which fracture surface indicates all mirror region. Below the minimum temperature, rising temperature is almost the same as lowering the molecular weights in terms of the mechanical property and mechanism of occurrence of the craze and fracture surface morphology.
Brittle region indicates the fracture with the unstable crack propagation and mirror region indicates the fracture with the stable crack propagation or craze propagation.
Ductile region indicates the fracture with the incorporation and growth of defects. Degree of fluidity is able to put a quantitative definition with the change of area of each region on fracture surface.
It is concluded that the reason for decrease of elongation of polystyrene is formation of the craze, the elongation decreases with increase of mirror region area on the fracture surface, and all fracture surfaces become mirror region at the temperature of minimum point of elongation.