Measuring the depth of fluorine incorporation in high and low density polyethylene by Rutherford backscattering spectrometry

Abstract

We report on our efforts to apply Rutherford backscattering spectrometry (RBS) for measuring the permeation of fluorine into low (LDPE) and high density polyethylene (HDPE) that have been exposed to gas atmospheres containing fluorine. To address the issue of sample damage during RBS analysis, experimental conditions were chosen using polytetrafluoroethylene as a standard. Our studies of LDPE and HDPE containers exposed to 1% fluorine in nitrogen atmospheres show the depth of fluorine penetration to be approximately 400 Å. Though the depths of treatment for both materials are quite similar, we find that the amount of fluorine uptake per unit volume is significantly higher for LDPE. The information yielded by RBS (depth of treatment and uptake per unit volume) shows it to be a powerful method for evaluating surface and near surface treatments of polymeric materials.