Effect of ultraviolet stabilizers on rubber-based automotive sealing profiles

Abstract

The sealing profiles for many visible and invisible automotive applications such as doors, windows, hoods and trunks are made of synthetic ethylene propylene diene monomer (EPDM) rubber. This combination of ethylene, propylene and unsaturated diene molecules exhibits high mechanical properties and forms a water-proof structure. With the progress of time, color change, cracking and staining can be observed on the surface of the sealing profiles used on the visible regions exposed to the sun due to the effect of high-intensity ultraviolet (UV) radiation and sunlight. The aim of this study was to investigate the effect of the UV stabilizers widely used in the plastics industry on the UV resistance of EPDM rubber. UV stabilizers protect the polymers against to UV radiation by reacting with the free radicals that are formed when a high energy UV photon causes a chemical bond in the polymer to break or by absorbing potentially destructive UV radiation. Plates of EPDM rubber were prepared by adding different types of UV stabilizers at different rates to an available EPDM formula. The effects of the UV stabilizers on the EPDM plates were measured by mechanical tests and the internationally recognized Florida outdoor aging test with climate conditions of high-intensity sunlight, high-intensity UV, and high temperature and humidity levels.