三元乙丙橡胶玻璃化转变温度以上的Sub-Rouse弛豫峰研究  

Sub-Rouse Mode Relaxation in Ethylene-propylene-diene Rubber above Glass Transition

作　　者：曹航[1,2] 顾振[3] 陈召[2] 李世源[2] 郑康[2] 秦勇[1] 田兴友[2] 张献[2] 

机构地区：[1]中国科学院固体物理研究所,合肥230031 [2]中国科学院合肥物质科学研究院应用技术研究所,合肥230088 [3]中国科学院理化技术研究所,北京100190

出　　处：《高分子学报》2016年第9期1206-1211,共6页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号51303182)资助项目

摘　　要：采用动态力学分析法(DMA)研究了三元乙丙橡胶(EPDM)的链段弛豫行为.结果表明随着温度的升高,EPDM样品依次出现了3个内耗弛豫峰,分别是玻璃化转变(α转变)、sub-Rouse模式转变(α'转变)和Rouse模式转变(α″转变).通过分析频率谱中弛豫时间、弛豫强度、耦合参数和形状因子分别随温度的变化,发现在温度为384 K处,sub-Rouse模式转变存在动态转折点TB.而且,转折点的弛豫时间τα'(TB)大约是0.11 s,这与文献报道的PS及PVAc/PEO共混物(10(-0.5±0.5)s)等材料的弛豫时间非常接近,表明该转折点是在特定的弛豫时间产生的.基于链段耦合模型,我们提出此转折点是由低于TB温度时分子间耦合增强引起的.The chain relaxation behavior of ethylene-propylene-diene rubber （EPDM） was investigated by dynamic mechanical analysis （DMA）. The results indicated that there were three tan8 peaks for EPDM at low frequencies,which were attributed to glass transition （c~ transition）, sub-Rouse mode （a＇ transition） and Rouse mode （a＂ transition） , respectively. In addition, compared with the glass transiton, sub-Rouse mode has a much stronger frequency-dependence, showing that the sub-Rouse mode moves to high temperature faster than the ct mode with the augment of frequency,which is sensible and consistent with the previous works as the local segmental motions are more intermolecularly coupled than the sub-Rouse mode relaxation in polymers,such as PS,PVAc and PMMA. After comprehensive analyses of frequency-domain spectra of EPDM via figuring out the temperature dependence of relaxation time, relaxation strength, coupling parameter and shape parameter, a dynamic crossover at TB -384 K was found in sub-Rouse （α） mode. What＇s more,the crossover relaxation time %, （ Ts ） is calculated as 0. 11 s, approximately, which is remarkably close to that of PS, PVAc and PVAc/ PEO blends （10（-0.5±5） s）, indicating that this crossover arises at a particular point of relaxation time. According to the coupling model, the crossover is suggested to be caused by the strong increase of intermolecular cooperativity below TB.

关 键 词：EPDM 弛豫时间 耦合模型 分子间协同性 

分 类 号：TQ333.4[化学工程—橡胶工业]