Enhancement of mechanical properties and thermal stability of recycled polyethylene, polypropylene and their blends via incorporation of elastomer

This study is conducted to look at the enhancement of the mechanical properties and thermal stability of recycled polyethylene (RPE), polypropylene (RPP) and their blends with the addition of styrene butadiene rubber (SBR). Mechanical properties include Shore hardness and impact strength, as well as thermal properties such as thermal stability, were all evaluated. The addition of SBR increased the impact strength of RPP (by 17%) and all RPP/RPE blends (by 34% to 123%). With adding SBR, the impact strength properties of the PP-rich blend were considerably improved in comparison to RPP, RPE, and other blends. With blends, the improvement in impact strength decreased as the RPP component was decreased. On the other hand, the addition of SBR resulted in a decrease in the impact strength of RPE (by 21%). Additionally, the hardness properties were not apparent affected by the addition of SBR in all cases. In line with the impact strength findings, RPP and all RPP/PE blends showed a slightly increased hardness (by 1%–3%) after the addition of SBR, whereas RPE exhibited decreased hardness (by 2%). In contrast to the impact strength results, the hardness increased as the content of RPE in blend composition increased. The thermal stability of RPP and all blends was clearly improved with the addition of SBR. Conversely, there was no improvement in RPE’s thermal stability with the addition of SBR. Overall, this study demonstrates that adding an elastomer, such SBR, could potentially enhance the mechanical properties and thermal stability of RPP and RPP/RPE blends.