Degradation Characterization of Ethylene-Propylene-Diene Monomer (EPDM) Rubber in Artificial Weathering Environment
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TECHNICAL ARTICLE—PEER-REVIEWED
Degradation Characterization of Ethylene-Propylene-Diene Monomer (EPDM) Rubber in Artificial Weathering Environment Quanlin Zhao • Xiaogang Li • Jianwen Hu Zhengfang Ye
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Submitted: 2 March 2010 / in revised form: 7 March 2010 / Published online: 19 March 2010 Ó ASM International 2010
Abstract Ethylene-propylene-diene monomer containing 5-ethylidene-2-norbornene as diene was exposed to artificial weathering environment produced by a xenon lamp light exposure and weathering equipment for different periods of time. The changes of surface color and mechanical properties were monitored by spectrophotometer, computer-controlled tensile testing and hardness measurements. Crosslink density of ethylene-propylenediene monomer specimens was measured by the solvent swell method. The results showed that the surface of ethylene-propylene-diene monomer became yellower due to the form of carbonyl group. The degradation process proceeded predominantly via cross-linking. With increase in crosslink density, the tensile strength increased and the elongation at fracture decreased. Keywords Degradation Ethylenepropylene-diene monomer Artificial weathering Crosslink density Mechanical properties
Q. Zhao (&) Z. Ye Department of Environmental Engineering, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Peking University, Beijing 100871, People’s Republic of China e-mail: [email protected] X. Li School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, People’s Republic of China J. Hu Materials Science and Engineering School, Hebei University of Science and Technology, Shijiazhuang 050054, People’s Republic of China
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Introduction Ethylene-propylene-diene monomer (EPDM) rubber is a kind of polymer material, which is composed of ethylene, propylene and unsaturated diene. It can be widely used in many fields [1–7] because its backbone is almost saturated. During outdoor applications, it is degraded by heat [8–10], radiation [11–13], chemical environment [14–17] and ozone [18, 19], which can cause the loss of bulk properties such as tensile strength and elongation at fracture and result in the reduction of the service life. It is therefore desirable to understand its degradation behavior in such conditions. In the laboratory, an artificial weathering test is often adopted to simulate a natural weathering test in order to evaluate the weather resisting properties of a material in a short time. Three kinds of lamps, xenon lamp, ultraviolet fluorescent lamp and carbon-arc lamp, are commonly used as light sources to simulate the ultraviolet radiation from sunshine and water is periodically sprayed on the material surface to simulate raining. Snijders et al. [20] studied the influence of the type and amount of diene on the stability of uncompounded EPDM in an artificial weathering device, in which a xenon lamp was used as light source. Aimura and Wada [21] investigated the aging behavior of EPDM in an artificial weathering
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