Aging in EPDM used for outdoor insulation

The effect of accelerated weather aging an ethylene-propylene-diene monomer (EPDM) rubber used for outdoor insulation was studied by surface roughness measurement and X-ray photoelectron spectroscopy(xps). The surface roughnes s of EPDM rubber changed with aging time. The surface oxygen and aluminum c ontent were found to increase and that of carbon, silicon and nitrogen to d ecrease with time. The detailed XPS analysis indicated that the concentrati on of carbon in C-C decreased and that of highly oxidized carbons in C-O, C =O and O=C-O increased with time, which was due to the oxidation of EPDM ru bber polymer. The appearance of O=C-O on the surface of EPDM rubber was a s ignal that EPDM rubber became aged. The aging speed decreased with time. Th e aging mechanism is discussed also.