EFFECTS OF $gamma$-RAY IRRADIATION ON POLYMERS. III. EFFECTS OF $gamma$- RAY ON MECHANICAL PROPERTIES OF FILAMENTS OF HIGH DENSITY POLYETHYLENE

For compiirison with low density polyethylene, the effects of irradiation on the mechanical properties of high density poivethylene filaments were studied. With the vacuum-irradiation, the tensile strength decreased with dose for the unelongated and slightly elongated samples; it was practically constant for highly eiongated samples. On the other hand, the tensile strength of the air-irradiated samples decreased considerably with dose. Young's modulus and degree of elasticity at 65% RH and 20 deg C were insensitive to dose, just as those of the low density polyethylene. The per-cent shrinkage of the irradiated filaments decreiised with dose, and the flow point rose in vacuum irradiation but fell in air-irradiation. (auth)