Mechanical, thermal, and rheological properties of dynamically vulcanized natural rubber-toughened polystyrene

Dynamically vulcanized blends of 85/15 polystyrene (PS)/natural rubber (NR) were prepared by melt mixing in an internal mixer at I70 degrees C using dicumyl peroxide (DCP). The concentration of DCP was varied from 0 to 4.2 milliequivalents (meq). It was found that dynamic vulcanization of the blend with 2.8 meq DCP significantly enhanced the Young's modulus, flexural modulus, and impact strength, with a marginal improvement in tensile and flexural strengths. The SEM studies revealed that the morphology of the blends changed drastically on dynamic vulcanization. The dynamic mechanical studies showed that the storage modulus and the loss modulus were better for dynamically vulcanized blends with 2.8 meq DCP in comparison to other blends. The rheology studies reveal that the damping of the blend was reduced at the melt processing conditions at a DCP content of 2.8 meq and the blend was pseudoplastic in nature. The thermal stability of the dynamically vulcanized blend improved on dynamic vulcanization. Thus, dynamic vulcanization can be employed as a means of technological compatibili-zation technique for 85/15 PS/NR blend for overall improvement in properties.