Investigation of effect of ultraviole (UV) stabilizers on rubber based sealings used in automotive sector

Airtight bands called sealing profiles are used in the automotive sector on many visible and concealed areas of vehicles including doors, windows, hoods (bonnets) and trunks (boots). They reduce driving noise in the vehicle, block entry of water, air, external noise and dust and enable motion of the doors, windows, etc. with minimal friction. Ethylene-Propylene-Diene Monomer (EPDM) is a type of rubber obtained by the addition of a diene monomer during the copolymerization of ethylene and propylene. Due to its easy workability and superior physico-mechanical properties, it is extensively used, especially in sealing profiles as well in the production of rubber hose and cables. However, as is the case with all polymeric materials, due to the effects of ultraviolet (UV) rays, subject to time, color changes and staining are observed in materials produced from EPDM. UV stabilizers and UV absorbers are widely-used to increase the UV resistance of thermoplastics. This study investigated the possibility of using these UV stabilizers and UV absorbers on the EPDM rubber currently used in sealing profiles. The effects of UV stabilizers and UV absorbers added in different amounts were investigated rheologically, mechanically and via the Florida artificial weathering test. Surfaces of samples before and after aging were analyzed via scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis and Fourier transform infrared spectroscopy (FTIR). The results showed that addition of Tinuvin-123 HALS (hindered amine light stabilizer) and Tinuvin-213 UV absorber together to EPDM rubber in the amount of 1.0 phr enhanced the UV resistance of the sealing profiles, and that Flamestab NOR 116 could be used as a UV stabilizer when added to EPDM rubber at 1.25–2.0 phr.