Comparison of the Different Vulcanization Techniques of Styrene Modified Natural Rubber (SNR) as an Impact Modifier of Natural Rubber-Based High Impact Polystyrene (NRHIPS)

Styrene modified natural rubber (SNR) is a modified rubber that can work as an impact modifier and compatibilizer for polystyrene (PS) matrix. The effect of different vulcanization techniques based on the sulfur vulcanization system has been investigated to produce SNR vulcanizates for natural rubber-based (NR) impact modifier for polystyrene. SNR is produced through emulsion polymerization of styrene monomer and deproteinized natural rubber (DPNR) latex. The styrene to DPNR ratio is 25:75 (wt/wt). SNR is vulcanized using sulfur vulcanization system with 1.5phr sulfur loading for each blend. Each PS/SNR blend contains 20% rubber. Three different vulcanization techniques are proposed to produce SNR vulcanizates: mixed system (in situ mixing together with physical mixing using two roll mills), in situ vulcanization, and physical mixing using two roll mills. PS/SNR blends show the in situ vulcanization process produce SNR vulcanizate, which gives the blends with better tensile properties and impact strength compared with the mixed system and physical mixing. The morphology in PS/SNR blends of PS/R1, PS/R2 and PS/R3 have further prove that SNR has better interaction with PS matrix compared with PS/*DPNR. PS/R3, which because they have in situ vulcanization SNR vulcanizate prepared by latex-based formulation, successfully produce SNR vulcanizates that can contribute as a natural rubber-based impact modifier.