A study on chemical modifications, mechanical properties and surface photo-oxidation of films of polystyrene (PS) stabilised by hindered amines (HAS)

The degradation of unstabilised and HAS-stabilised polystyrene (PS) films is described. The films have been exposed to accelerated weathering in a Xenotest Alpha apparatus to mimic outdoor conditions (lambda > 300 nm). Fourier transform infrared spectroscopy (FT-IR) and gel permeation chromatography (GPC) have been used to investigate the changes of the chemical structure and X-ray-photoelectron spectroscopy (XPS) to study the surface photo-oxidation. Mechanical properties (i.e. stress at the breaking point (sigma(b)), strain at the breaking point (epsilon(b))) were found to be very sensitive to the degree of surface oxidation. The stabilising action of the HAS affected both the bulk and the surface. (C) 2004 Elsevier Ltd. All rights reserved.