ELECTRON SPIN RESONANCE INVESTIGATION ON NEUTRON IRRADIATED POLYPROPYLENE

Abstract

Investigation on neutron irradiated isotactic polynropylene was done by electron spin resonance experiments to study the effect of the ionizing radiation on radical formation, cross linking, and formation of the chemical bond. The samples of polypropylene were pile irradiated at neutron dosages of 5.4 x10/sup 17/, 6.8 xl0/sup 17/ 5.7 x10/sup 18/ and 140 x l0/sup 18/ nvt. As the irradiation dose increases, the line becomes more sharp. There is a marked decrease in half-width with increase in irradiation dose. There was evidence of the presence of some methyl groups in the irradiated speci-men, though some of the methyl groups are destroyed by irradiation. It is more likely that color formation could be due to a conjugated double bond stmcture than to a long life radical. Narrowing of the line width, in this case, is not due to exchange interaction of the unpaired electrons but is due to an increase in the conjugated region of the double bond structure with the stable radical formed by neutron irradiation. The increase in the conjugated region lowers the neighbor interaction, on account of which there is a narrowing of the line width with increase in dose at high neutron dosages. (auth)