Morphology development in thermoplastic vulcanizates (TPV): Dispersion mechanisms of a pre-crosslinked EPDM phase
Morphology development in thermoplastic vulcanizates (TPV): Dispersion mechanisms of a pre-crosslinked EPDM phase
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DOI：
10.1016/j.eurpolymj.2009.07.012
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发表时间：
2009-11-01
影响因子：
6
通讯作者：
Cassagnau, P.
中科院分区：
文献类型：
--
作者：
Martin, G.;Barres, C.;Cassagnau, P.
研究了几种预交联增塑的三元乙丙橡胶(EPDM)网络在熔融PP中的裂解和分散情况。因此，比较了未交联型、预交联型和动态交联型EPDMS组成相近的PP/EPDM共混物的形态和力学性能。结果首先强调了预交联型EPDM凝胶分数的重要性，以及热塑性基质比例对此类网络分散质量的影响。结果，在PP的存在下，凝胶分数低于g(EPDM)=0.7的预交联型三元乙丙橡胶可以被精细而均匀地碎裂和分散。由此可以认为三元乙丙橡胶微区的侵蚀机制是碰撞-合并-分离的。然而，与一些理论模型的预期相反，即使在非常高的交联密度下，也总是观察到化学网络的部分碎裂(g(EPDM)>；0.7)。最后，剪切交联型(动态交联型)共混物由于其细小均匀的形态和弹性体的完全交联性而表现出明显的力学性能协同效应。最后，这些结果为热塑性弹性体的形态稳定性及其相关力学性能提供了重要的信息。(C)2009爱思唯尔有限公司。保留所有权利。
The fragmentation and dispersion in molten polypropylene (PP) of several pre-crosslinked and plasticized ethylene-propylene-diene terpolymer (EPDM) networks was studied. Thus, the morphologies and mechanical properties of PP/EPDM blends having similar compositions but made from either un-crosslinked, pre-crosslinked or dynamic-crosslinked EPDMs were compared. The results first highlight the importance of the gel fraction of the pre-crosslinked EPDMs, as well as the impact of the thermoplastic matrix proportion on the quality of the dispersion of such networks. As a result, pre-crosslinked EPDM having a gel fraction below g(EPDM) = 0.7 can be finely and homogeneously fragmented and dispersed in presence of PP. It can be then admitted a collision-coalescence-separation type erosion mechanism of the EPDM domains. Nevertheless, contrarily to some theoretical model expectations, a partial fragmentation of the chemical networks was always observed even at very high crosslink density (g(EPDM) > 0.7). Finally, the blends crosslinked under shearing (dynamic-crosslinked) showed a clear mechanical property synergy due to their fine and homogeneous morphology coupled with the full crosslinking of the elastomer. in the end, these results brought significant information on TPV morphology stabilization and their related mechanical properties. (C) 2009 Elsevier Ltd. All rights reserved.