门尼粘度及支化程度对三元乙丙橡胶性能的影响

通过无转子硫化仪、橡胶加工分析仪、核磁交联密度仪等分析手段研究三元乙丙橡胶(EPDM)的门尼粘度、长链支化程度对过氧化物硫化EPDM的硫化特性及其硫化胶性能的影响。结果表明,门尼粘度的增加,有助于交联密度和硫化速率的提高,横向弛豫时间不断减小。高支化程度对EPDM胶料硫化速度不利。EPDM门尼粘度越高,初始储能模量G′0越大,储能模量迅速下降的临界应变值越小;不同长链支化度的EPDM硫化胶的储能模量大致相等,但长支化链的损耗因子值相对较高。门尼粘度对EPDM硫化胶拉伸强度变化影响较小;而长链支化程度的提高,使硫化胶拉伸强度和断裂伸长率略微降低。

Effect of Mooney viscosity and branching degree on the properties of ethylene propylene-diene rubber

In this paper,the influence of structural parameters such as Mooney viscosity,branching degree of ethylene-propylene rubber（EPDM） chains on the cure characteristics and the properties of EPDM vulcanizates was discussed by the moving die rheometer（MDR）,rubber processing analyzer （RPA）,nuclear magnetic resonance（NMR） spectroscopy and other analytical methods.The results showed that the increase of Mooney viscosity was beneficial for the improvement of the crosslinking density and curing rate,which also made the transverse relaxation time of EPDM vulcanizates decrease.The EPDM with higher branching degree of long chain showed a slower curing rate.Furthermore,the higher the Mooney viscosity,the more the original storage modulus G＇0,the less the critical strain where the storage modulus decreased quickly.The EPDM vulcanizates with different branching degree nearlyshowed the equal G＇,but the vulcanizate with a long branching chain had a high loss factor.Moreover,the Mooney viscosity of EPDM showed little influence on the tensile strength,while the tensile strength and the elongation at break of EPDM vulcanizates decreased slightly when the branching degree of long chain improved.