Polymer Testing, ARLANXEO Deutschland GmbH, Kaiser-Wilhelm-Allee 40, 51369 Leverkusen, Germany.
Soft Matter. 2017 Jun 14;13(23):4241-4251. doi: 10.1039/c7sm00264e.
The fatigue properties of cross-linked blends of ethylene propylene diene rubber (EPDM) with low natural rubber (NR) content and reinforced with carbon black (CB) are studied. It is found that such EPDM/NR compounds have superior crack growth resistance and fatigue lifetime. For low NR contents, transmission electron microscopy reveals that the NR phase forms small droplets of 20-50 nm. Remarkably, these droplets are even smaller than the primary CB particles. Atomic force microscopy shows that the the NR phase droplets have a higher loss factor and a smaller elastic modulus than the surrounding EPDM matrix. Rheometer measurements are used to study the effect of the phase morphology on the rubber mechanical properties. These rheological data are compared with the prediction of the Eshelby model describing the effect of elastic inclusions on solids. A complex interplay between the rubber phase morphology and the solubility of both the sulfur cross-linking system and CB is observed, which cannot be predicted theoretically. It is proposed that the soft NR droplets effectively inhibit the crack propagation in the EPDM matrix.
交联共混物的疲劳性能研究了低天然橡胶（NR）含量的三元乙丙橡胶（EPDM）与炭黑（CB）增强的共混物。研究发现，这种 EPDM/NR 化合物具有优异的抗裂纹扩展能力和疲劳寿命。对于低 NR 含量，透射电子显微镜显示 NR 相形成 20-50nm 的小液滴。值得注意的是，这些液滴甚至比初级 CB 颗粒还要小。原子力显微镜显示，与周围的 EPDM 基体相比，NR 相液滴具有更高的损耗因子和更小的弹性模量。流变仪测量用于研究相形态对橡胶力学性能的影响。将这些流变数据与描述弹性夹杂对固体影响的 Eshelby 模型的预测进行了比较。观察到橡胶相形态和硫磺交联体系以及 CB 的溶解度之间存在复杂的相互作用，这是无法从理论上预测的。提出软 NR 液滴有效地抑制了 EPDM 基体中的裂纹扩展。
