Effect of gamma irradiation on optical properties of Kapton

Study of optical properties of gamma irradiated Kapton foil is presented. These foils are irradiated for doses ranging from 10 to 500 kGy. The irradiated (10-50 kGy) Kapton shows a uniform increase in visible absorption from 500 to 800 nm, which decreases for further irradiation up to 500 kGy. Similar increase and decrease in IR absorption peaks are also noted along with absorption of water moisture in the irradiated Kapton at lower dose (∼10 kGy). Results indicate that chain scissioning creates various types of defects and radicals at low doses whereas reorganization/cross linking of bonds is taking place at higher doses (> 50 kGy). The presence of moisture absorbed at low doses of irradiation play an important role in reorganization of bonds as well as in cross linking process at comparatively higher doses of irradiation (> 50 kGy).