Physical properties of electron beam irradiated poly(vinyl butyral) composites with carbamate, imidazole, and tetrazolium dye

Abstract

Films of poly(vinyl butyral) composites with triphenyl tetrazolium chloride dye (TTC) and the antioxidant nickel dibutyl dithiocarbamate (NEC) or 2-mercapto-benzimidazole (MBI) were prepared by the solution casting method using butyl alcohol as a solvent. The effect of various doses of electron beam irradiation (50-200 kGy) on color response, thermal, and mechanical properties were investigated. The color measurements showed that the films of the different composites possessed a high sensitivity to electron beam irradiation, in which the nearly colorless films were changed to deep red color, which can be easily detected by visual observations. In addition, the change in color depends on irradiation dose and the contents of the TTC dye. Moreover, the presence of the antioxidants NEC or MBI has no effect on the development of color. However, PVB/TTC and PVB/TTC/MBI composites showed high regular change in color as a function of irradiation dose. The thermogravimet rie analysis used to study the thermal stability indicated that PVB/TTC composites either before or after electron beam irradiation are thermally more stable than neat PVB polymer. The presence of the antioxidants NEC or MBI offered protection to PVB/TTC composites against decomposition or oxidative degradation resulted from irradiation. Blending unirradiated PVB with TTC dye, mixture of TTC and NEC, and mixture of TTC and MBI reduced the tensile strength by 4, 20, and 17% upon blending, respectively. However, the reduction in tensile strength of the entire composite films (∼7% based on the initial value) upon exposure to a dose of 50 kGy is acceptable for practical applications. © 2006 Wiley Periodicals, Inc.