Suppression of radiation-induced oxidation of polymers by sputtered silicon oxide coating

Abstract

Oxygen barrier coating on polymers was attempted to obtain polymeric composite materials with improved radiation resistance. Silicon oxide (SiO1.6) films ranging from 120 to 240 nm thick were formed on polypropylene (PP) and polyethylene (PE) by radio frequency (RF) magnetron sputtering. Oxygen permeability after SiO1.6 deposition was reduced significantly in all samples studied, indicating that silicon oxide is a useful gas barrier. The oxygen permeability coefficient of deposited films for PP was 1.7-2.2 × 10-14cm3-cm/cm2/s/cmHg and that for PE was 2.8-4.8 × 10-13 cm3-cm/cm2/ s/cmHg. We studied the effect of such films on the radiation resistance of polymers in the presence of oxygen by microscopic infrared (IR) absorption spectroscopy. Silicon oxide films 180 nm thick were deposited on the surfaces of PP and PE, and the formation of carbonyl groups after irradiation in air was measured as a function of depth from the surface. Results compared with those for uncoated PE and PP showed that the radiation-induced polymer oxidation is dramatically suppressed by silicon oxide coating. © 2002 John Wiley & Sons, Inc. J. Appl. Polym. Sci.