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

摘要

The photo-oxidation of high density polyethylene (HDPE) (unfilled and CaCO_3 mineral filled), after accelerated irradiation in a UV-weathering chamber, was studied by using different analytical techniques. The FTIR, DSC and viscometry results for irradiated unfilled HDPE, show that this material degrades, in general terms, following a free-radical chain mechanism in three stages. The presence of the CaCO_3 mineral filler changes the photo-degradation of the HDPE. The results showed that the mineral filler inhibits the formation of the γ-lactone group, and slows the carbonyl and hydroperoxide functional group formation during the UV irra- diation of the filled HDPE, i.e. the mineral filler acts as a protective barrier for the UV light penetration in the HDPE. The scanning electron microscopy (SEM) microphotographs of degraded specimen surface reveal a significant difference in surface topography of unfilled and mineral filled HDPE.