Weatherability of coated EPDM rubber compound by controlled UV irradiation

Polymeric composites for automotive window seal applications are generally exposed to complex service environment conditions. The fundamental physico- chemical processes that control the durability of such composite systems on a micro and macroscopic level were evaluated in the present case using the rmal analysis (TA), elemental mapping and microscopy. Five different EPDM r ubber compounds (control, three bulk modified and one surface modified), co ated with polyurethane coating were exposed to controlled UV irradiation. T he higher the adhesion, the less the extent of UV penetration through the i nterface. The photo-oxidation mainly takes place from the surface, as the e nergy gets consumed and the intensity of the UV decreases on its passage th rough the strongly adhered layers to the rubber compound. The coating layer being on the surface, is more affected and photodegraded by UV irradiation than the rubber compound. The sample P-1cc,P- being multiphasic in nature and with a strong interface, can scatter the UV strongly and hence shows be st weatherability among all the systems. (C) 2000 Elsevier Science Ltd. All rights reserved.