Investigations on the electrical and structural properties of electron-beam irradiated polyurethane

The effect of electron-beam (eb) irradiation on the electrical, optical, thermal and structural properties of polyurethane-elastomer (Pu) sheets of thickness 0.076mm was investigated. The samples were exposed to eb at ascending dose levels in the range 90-300 kGy. Optical properties and structural studies using Fourier transform infrared measurements and x-ray diffraction technique were performed on un-irradiated and irradiated samples. Dc-conductivity measurements were carried out in the temperature range 306-413 K. It was found that the electrical conductivity of polyurethane-elastomer increased due to eb irradiation via degradation mechanisms. Furthermore, the activation energy was calculated, as a function of the eb doses. Also, at the eb irradiation doses, in the range 200-300 kGy, radiation causes branching that reduces crystallinity and induces further lattice defects that may act as scattering centres and energy barriers for the flow of electric current. Thermal gravimetric analysis study indicates the degradation of Pu due to eb irradiation, which causes the samples to start decomposition later than un-irradiated ones. The differential thermal analysis measurements exhibit a significant change in their melting behaviour.