THERMAL-EXPANSION OF IRRADIATED POLYPROPYLENE FROM 10-340-K

The coefficient of thermal expansion of gamma-irradiated polypropylene (PP) has been measured from 1 0-340 K by using the three-terminal capacitance technique. The samples were irradiated to 500 Mrad in air at room temperature with gamma rays from a Co-60 source at a dose rate of 0.26 Mrad h-1. The crystallinity of the sample was measured by X-ray diffraction technique. The crystallinity was found to decrease with radiation dose from 55% at 0 Mrad to 44.7% at 500 Mrad. The thermal expansion coefficient was found to be almost constant with radiation dose from 10-125 K and decreases with radiation dose from 125-340 K.