Detection of radiation deformation in crystalline polymers using the speckle photography technique

Abstract

In order to measure the resulting deformation due to gamma irradiation of polymers, a new optical technique, namely speckle-photography, was established and used. Thin films of tetrafluroethene, with constant thickness were irradiated by different doses of gamma rays and the diffraction patterns of a laser beam passing through these films were recorded using the speckle photography technique. This technique has been applied to detect the radiation deformation in (Teflon) TFE, which is a crystalline polymer. A diffraction pattern due to the TFE thin layer is obtained and superimposed on the interference pattern displaying the speckle pattern pairs recorded on the same emulsion. The intensity of the obtained diffraction pattern was found to decrease by increasing the radiation dose from 5 to 12 Mrad from a Cobalt-60 source, and it vanishes at 12 Mrad dose. This may be attributed to the decrease in the degree of crystallinity of the TFE polymer with increasing radiation dose.