DYNAMICALLY VULCANIZED THERMOPLASTIC ELASTOMERS BASED ON DIFFERENTLY STRUCTURED STYRENE-BUTADIENE-RUBBERS AND ON POLYPROPYLENE
Over the past few decades, the production and use of thermoplastic elastomers (TPEs) has been intensively developing worldwide. These materials have unique properties, since they combine the properties of thermoplastics and vulcanized rubbers and, unlike the traditional rubber processing technology, they are recyclable. There is little information in the literature about using styrene-butadiene rubbers (SBRs) in the composites of blended thermoplastic elastomers. And about thermoplastic vulcanizates (TPV), there is just little information on how they are prepared in the presence of bis-maleimides. We have previously investigated SBR- and HDPE-based TPVs and shown that, in the presence of sulfur-accelerating systems, composites with good properties are obtained with the ratio of elastomer to thermoplastic within 70:30-60:40. In this study, we have investigated the properties of dynamically vulcanized TPEs based on SBRs polymerized in an emulsion or a solution and on polypropylene, all in the presence of a vulcanizing system based on a combination of sulfur and sulphenamide accelerator. As an elastomeric phase, we investigated SBRs, such as SKMS-30 ARKM-15, VSL 2438, and VSL 5025 (LANXESS, Germany), having different microstructures and using different preparation methods. It is shown that, in using VSL 2438 and VSL 5025, TPEs with a higher tensile strength are obtained, as compared to SKMS-30 ARKM-15. However, for all the composites, sufficiently high values of residual elongations are observed. To improve this indicator, sulfur dosages were increased in obtaining the composites, which allowed us to increase by changing the rubber phase vulcanization degree to increase the strength properties, maintain the level of relative elongation, and reduce the residual elongation by 15-20%.