Mineral filler influence on the photo-oxidation of high density polyethylene: I. Accelerated UV chamber exposure test

The photo-oxidation of high density polyethylene (HDPE) (unfilled and CaCO3 mineral filled), after accelerated irradiation in a UV-weathering chamber, was studied by using different analytical techniques. The FTIR, DSC and vi scometry results for irradiated unfilled HDPE, show that this material degr ades, in general terms, following a free-radical chain mechanism in three s tages. The presence of the CaCO3 mineral filler changes the photo-degradati on of the HDPE. The results showed that the mineral filler inhibits the for mation of the gamma-lactone group, and slows the carbonyl and hydroperoxide functional group formation during the UV irradiation of the filled HDPE, i .e. the mineral filler acts as a protective barrier for the UV light penetr ation in the HDPE. The scanning electron microscopy (SEM) microphotographs of degraded specimen surface reveal a significant difference in surface top ography of unfilled and mineral filled HDPE. (C) 1999 Elsevier Science Ltd. All rights reserved.