Photoluminescent properties of flexible PVC compounds and their interpretation for performance analysis of automotive exterior parts

Study of fluorescence emission from flexible WC-based formulations, colored by exposure to road asphalt or degraded thermally or by W aging, shows that fluores- cent species are formed during the interaction of PVC with road asphalt. For the conditions found in exterior automotive applications, n o other known degradation causes development of fluorescence. Flexible PVC-based formulations discolored by asphalt staining or degraded thermally a t moderate temperatures bleach completely under conditions of natural or artificial weathering. A simple technique, using visu- ally observed photoluminescence and photobleaching, c a n thus identify photoactive groups formed during the interaction of PVC with road asphalt. Application of this test method will allow selective improvement of failed asphalt resistance without treating the "overall" stability of a compound.