Pirityi Dávid Zoltán, Pölöskei Kornél
Department of Polymer Engineering, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, Műegyetem Rakpart 3., H-1111 Budapest, Hungary.
Polymers (Basel). 2021 Apr 1;13(7):1116. doi: 10.3390/polym13071116.
Rubber waste remains a challenge for material science because its covalently cross-linked structure hinders the establishment of the circular economy of rubber. Devulcanisation may provide a solution, as it converts rubber vulcanisates back into their original, uncured state. Devulcanised rubber may be revulcanised or incorporated into virgin rubber, thus waste is utilized and the use of primary resources is reduced at the same time. In this paper, we treated sulphur-cured EPDM (ethylene propylene diene monomer) rubber on a two-roll mill at various temperatures and frictions. We determined the effectiveness of devulcanisation via Horikx's analysis, which suggested that low devulcanisation temperatures would result in a 50% decrease in cross-link density with minimal polymer degradation. The devulcanisate was recycled via two methods: (a) revulcanisation with extra curing agents, and (b) mixing it with various amounts of the original rubber mixture, preparing rubber samples with 25, 50, 75, and 100 wt% recycled content. Tensile tests revealed that the samples' elastic properties were severely compromised at 75 and 100 wt% devulcanisate contents. However, tensile strength decreased only by 15% and 20% for revulcanisates containing 25% and 50% recycled rubber, respectively.
橡胶废料仍然是材料科学面临的一个挑战，因为其共价交联结构阻碍了橡胶循环经济的建立。脱硫可能提供一种解决方案，因为它能将橡胶硫化物转化回其原始的未硫化状态。脱硫橡胶可以再次硫化或掺入原生橡胶中，从而实现废料的利用，同时减少原生资源的使用。在本文中，我们在双辊炼胶机上于不同温度和摩擦力下对硫磺硫化的三元乙丙橡胶（EPDM）进行了处理。我们通过霍里克分析确定了脱硫的有效性，该分析表明，较低的脱硫温度会使交联密度降低50%，同时聚合物降解最小。脱硫产物通过两种方法进行回收：（a）用额外的硫化剂再次硫化，以及（b）将其与不同量的原始橡胶混合物混合，制备回收含量为25%、50%、75%和100%的橡胶样品。拉伸试验表明，在脱硫产物含量为75%和100%时，样品的弹性性能严重受损。然而，对于含有25%和50%再生橡胶的再次硫化产物，拉伸强度仅分别降低了15%和20%。
