A NEW TECHNIQUE TO QUANTIFY OXYGEN DIFFUSION IN POLYMER-FILMS

Diffusion coefficients for oxygen in polymer films are quickly and accurately obtained by using a near-infrared luminescence spectrometer. The spectroscopic technique described herein uses the 1270-nm phosphorescence of singlet molecular oxygen (1-DELTA(g)O2 --> 3-SIGMA(g)O2) to directly monitor oxygen sorption into polymer films (15-80-mu-m thick) of small area (approximately 1 cm x 1 cm). The approach is illustrated by using films of polystyrene for which a 25-degrees-C diffusion coefficient of (2.3 +/- 0.3) X 10(-7) cm2/s is obtained.