文章摘要
Study on Medium Ageing Behavior and Mechanism of EPDM Seals in Simulated Tunnel Strata Environment
Received:November 15, 2018  Revised:November 15, 2018
DOI：10.12136/j.issn.1000-890X.2019.05.0323
Key Words: EPDM；seal；aging behavior；aging mechanism；simulated tunnel strata environment medium；water absorption rate
Author NameAffiliationE-mail
DING Yuqiao China Railway Eryuan Engineering Group Co. ，Ltd TrusmanLee@163.com 
LI Chengjie Sichuan University  
YANG Zheng China Railway Eryuan Engineering Group Co. ，Ltd  
YUAN Zun Sichuan University  
YE Lin* Sichuan University yelinwh@126.com 
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Abstract:
      The aging behavior and mechanism of EPDM seal in simulated tunnel strata environment medium with concentration of 1 mol·L-1（1M） ionic solution were investigated by comparing with distilled water.The results showed that the hardness and compressive strength of EPDM seals soaked in two kinds of media increased with aging time prolonging，the tensile strength decreased first and then increased，the elongation at break and compression permanent deformation were reduced，and the stress relaxation coefficient was improved.The reason was the permeation and diffusion of water molecules in the media in the EPDM matrix at the initial stage of aging，so that the reinforcing effect of reinforcing agent was weakened.The water absorption reached equilibrium in the middle and late aging period，and then crosslinking reaction occurred.The relative mass change rate and relative water absorption rate of EPDM seals increased first and then decreased，while storage modulus（E""） and glass transition temperature（Tg） showed a trend of first declining and then rising.The surface of EPDM seal gradually became rough during aging，and solid particles were separated.The aging rate of EPDM seal soaked in 1M ionic solution was slightly higher than that soaked in distilled water.The relative mass change rate and relative water absorption rate of EPDM seals soaked in distilled water were obviously higher than those soaked in 1M ionic solution，which was related to their high water absorption rate.At the same aging time，the E"" of EPDM seals soaked in 1M ionic solution was larger than those soaked in distilled water，while the Tg was lower.
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