MECHANICAL-PROPERTIES OF MOLDED SPECIMEN FROM POLYPROPYLENE FILM IRRADIATED WITH GAMMA-RAYS IN ACETYLENE GAS A ATMOSPHERE

Bulky materials reclaimed from waste plastics are not adequate to use as structual materials since mechanical properties of them are relativ ely low. In the present work polypropylene (PP) films, which are a pot ential main component of waste plastics in near future, were irradiate d with gamma rays in acetylene gas atmosphere and then were injection molded to PP test specimens to measure its mechanical properties. The flexural strength and modulus of elasticity in bending have been found to increase with irradiation dose. Those values reach the maximum at the irradiation dose of 40 similar to 80 kGy. In the case of the gas p ressure of 199 kPa and the irradiation of 57 kGy, the observed strengt h and modulus of elasticity of the PP specimen are 59 MPa and 2,050 MP a, respectively, which are 1.5 times and 1.7 times as large as those o f unirradiated PP. The tensile properties of the PP Specimen also are improved by 1.4 times of unirradiated PP. The acetylene gas pressure h as little influence to improve the properties in a range above 100 kPa . The injection molding after the irradiation is considered to be effe ctive to improve the mechanical properties of the PP specimen since th e heating and mixing of irradiated films enhance the crosslinks of ace tylence to PP structures and the network formation.