Scanning electron micrographs of solution casted NRL/PS and TWL/PS blends are shown in Figs. 3 and 4, respectively. Fig. 3 shows the rubber particles are round shape and PS are flake shape, the amount of rubber particles increases as the rubber proportion increased. Morphology for the 30/70 and 50/50 TWL/PS, the PS region formed a wall structure as shown in Figs. 4 (a) and (b). This is because TWL contains crosslinked molecules, which have high surface tension in their own network (Fukahori, 2010). It hardly entangles with other polymer chains and after mixing process the network molecule and other polymer which easily can be distinguish. Hence, the TWL and PS phases are clearly separated at composition of 30/70 and 50/50 TWL/PS, which causes poor interfacial interaction between the phases and gave much lower tensile and tear strengths compared to NRL/PS at similar composition. However, 70/30 TWL/PS showed better morphology without the phase separation. It may due to PS which dispersed in TWL at this composition. There is possible limit the dispersed amount of PS in TWL matrix, in case amount of PS is more then it would formed another region (PS wall in case of 30/70 and 50/50 TWL/PS). Moreover, 70/30 TWL/PS showed the smaller particle size compared to NRL/PS at any composition due to NRL particle size is not stable and possible to combine with other particle after mixing process due to uncrosslinking hence NRL show bigger particle size which contribute to higher tensile and tear strengths.
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Based from the results, the 70/30 TWL/PS blend shows better tensile, tear and morphological properties compared to other composition; thus, it was selected for further study.