Surface degradation of ethylene–propylene–diene monomer (EPDM) containing 5-ethylidene-2-norbornene (ENB) as diene in artificial weathering environment

Abstract

Ethylene–propylene–diene monomer (EPDM) containing 5-ethylidene-2-norbornene (ENB) as diene was exposed to an artificial weathering environment produced by a xenon lamp light exposure and weathering equipment for different time periods. The surface chemical changes were detected by Specular Reflection Fourier Transform Infrared (SR-FTIR) spectroscopy, Raman spectroscopy and X-ray Photoelectron Spectroscopy (XPS). The change in surface color, contact angle and morphology was monitored by spectrophotometer, optical contact angle measuring device and Scanning Electron Microscope (SEM). Furthermore, surface energy was calculated through contact angles of water and formamide. The results showed that hydroxyl, carbonyl and ester groups were formed during exposure to this artificial weathering environment. EPDM surface became redder, yellower and lighter in the first stage of aging and then remained almost unchanged. The contact angles of water and formamide decreased to a minimum and then increased slowly. The surface degradation is a zero order reaction. In addition, the plausible degradation mechanism was proposed.