Persson Anna-Maria Märta Ruth, Andreassen Erik
Dept. of Manufacturing and Civil Engineering, NTNU, P.O. Box 191, 2802 Gjøvik, Norway.
Polymer and Composite Materials Group, SINTEF Industry, P.O. Box 124 Blindern, 0314 Oslo, Norway.
Polymers (Basel). 2022 Mar 24;14(7):1316. doi: 10.3390/polym14071316.
Thermoplastic elastomer vulcanizate (TPV) and liquid silicone rubber (LSR) are replacement candidates for ethylene-propylene-diene rubbers (EPDM), as they offer the possibility for two-component injection moulding. In this study, these material types were compared side by side in cyclic compression tests. The materials were also characterized to provide details on the formulations. Compared to the rubbers, the TPV had higher compression set (after a given cycle) and hysteresis loss, and a stronger Mullins effect. This is due to the thermoplastic matrix in the TPV. The LSR had lower compression set (after a given cycle) than the EPDM, but stronger Mullins effect and higher relative hysteresis loss. These differences between the LSR and the EPDM are likely due to differences in polymer network structure and type of filler. Methods for quantifying the Mullins effect are proposed, and correlations between a Mullins index and parameters such as compression set are discussed. The EPDMs showed a distinct trend in compression set, relative hysteresis loss and relaxed stress fraction vs. strain amplitude; these entities were almost independent of strain amplitude in the range 15-35%, while they increased in this range for the TPV and the LSR. The difference between the compression set values of the LSR and the EPDM decreased with increasing strain amplitude and increasing strain recovery time.
热塑性弹性体硫化胶（TPV）和液态硅橡胶（LSR）是乙丙二烯橡胶（EPDM）的替代候选材料，因为它们提供了双组分注塑成型的可能性。在本研究中，这些材料类型在循环压缩试验中进行了并排比较。还对这些材料进行了表征，以提供配方细节。与橡胶相比，TPV具有更高的压缩永久变形（在给定循环后）和滞后损耗，以及更强的穆林斯效应。这是由于TPV中的热塑性基体。LSR的压缩永久变形（在给定循环后）比EPDM低，但穆林斯效应更强，相对滞后损耗更高。LSR和EPDM之间的这些差异可能是由于聚合物网络结构和填料类型的差异。提出了量化穆林斯效应的方法，并讨论了穆林斯指数与诸如压缩永久变形等参数之间的相关性。EPDM在压缩永久变形、相对滞后损耗和松弛应力分数与应变幅度方面呈现出明显的趋势；在15 - 35%的范围内，这些量几乎与应变幅度无关，而对于TPV和LSR来说，它们在这个范围内会增加。LSR和EPDM的压缩永久变形值之间的差异随着应变幅度的增加和应变恢复时间的增加而减小。
