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Entanglement Locking in the Unique Elasticity of Polydimethylsiloxane Rubbers
Macromolecular Chemistry and Physics ( IF 2.5 ) Pub Date : 2020-04-13 , DOI: 10.1002/macp.201900497
Vincenzo Villani 1 , Vito Lavallata 1
Affiliation  

The viscoelasticity behavior of the polydimethylsiloxane (PDMS) rubber blends of high molecular weight polymers modified by low molecular weight agents is studied in compression mode by stress–strain curves, the creep and step‐strain, and dynamic‐mechanical experiments. The strain spectra highlight the dynamics of active chains at high frequencies and of dangling ends in the low frequencies field. At low deformation, the blending agent enhances the elastic properties by increasing the density of the active chains in the rubber network, in agreement with the classical theories of elasticity. At high deformation, in analogy with the rheological studies on similar liquid blends, the Entanglement Locking model is proposed: the short chains of the blending agent are adsorbed on entanglement sites of long dangling chains, giving effective crosslinks via high entropy dynamics. In this way, the long‐term entanglement locking enhances the density of active chains and elastic behavior. At high deformation, the entanglement locking model enriches the rubber elasticity theories according to the tube network model and Mooney–Rivlin equation. The models herein and the possibility they offer for improving rubber viscoelasticity are valuable for the development of polymer physics and technology.

中文翻译:

纠缠锁定在聚二甲基硅氧烷橡胶的独特弹性中

通过应力-应变曲线,蠕变和阶跃应变以及动态力学实验,以压缩模式研究了由低分子量剂改性的高分子量聚合物的聚二甲基硅氧烷(PDMS)橡胶共混物的粘弹性行为。应变谱突出了高频处的活动链和低频场中悬空末端的动力学。在低变形下,与经典的弹性理论相一致,共混剂通过增加橡胶网络中活性链的密度来增强弹性。在高变形下,类似于对类似液体混合物的流变学研究,提出了缠结锁定模型:混合剂的短链吸附在长悬链的缠结点上,通过高熵动力学提供有效的交联。通过这种方式,长期的纠缠锁定可以提高活动链的密度和弹性。在高变形下,缠结锁定模型根据管网模型和Mooney-Rivlin方程丰富了橡胶弹性理论。本文中的模型及其为改善橡胶粘弹性提供的可能性对于聚合物物理和技术的发展具有宝贵的价值。
更新日期:2020-04-13
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