Effect of fraction and type of compatibilizer on morphology of polymer blends PS/PC

Effect of compatibilizer on morphology in ternary component polymer blends was studied. Samples of polystyrene (PS), polycarbonate (PC) with the third polymer a) polymethylmetacrylate (PMMA) and b) random copolymer polystyrene-co-polymethylmetacrylate (PS-co-PMMA) were prepared in micro extruder. Fraction of each component in studded blends is denoted by index, and has been given in Experimental part. In samples of series i) the fraction of compatibilizer PMMA was maintained constant and the fractions of two main polymers in blends were changed. In series ii) and iii) the ratio of two main components were maintain constant and the fraction of compatibilizers were changed. The morphology was studied by transmission electron microscope (TEM) and by scanning electron microscope (SEM). In this work the effect of type of compatibilizer and effect of their concentration on morphology and on the size of dispersed domains in ternary polymer blends were studied. From literature15,16 it is known that fraction of polymers in blend has strong influence on type of morphology. That can be observed on micrographs a), b) and c) of Fig. 1. Continuous phase usually form polymer in higher fraction and that is PS on Fig. 1a) and PC/PMMA on Fig. 1c). As the ratio of two main polymers PC and PS increase to one the phases coarse and form cocontinuous phase, Fig. 1b). These types of morphology can be expected when two polymers are miscible or compatible. It is possible to achieve such type of morphology when the third component that act as compatibilizer is added in blends when immiscible polymers are considered. The effect of fraction of the third polymer PMMA in studded blends on morphology is noticed on micrographs a), b), c) of Fig. 2, where PS make one phase, black and PMMA with PC form another phase, grave. By variation of the concentration of PMMA the ratio of PS to PC/PMMA in blend is changed and different morphology is observed. In samples in Fig. 2a) PS is dispersed in matrix of PC/PMMA and form discontinuous phase, on the other hand when ratio of PS to PC/PMMA is 1:1 PS form matrix because PS is less viscous than PC/PMMA, Fig 2c). While the cocontinuous phases are observed in Fig. 2b) when PC/PMMA are in slightly higher fraction then PS, and it can be concluded that the cocontinuous morphology is stable in narrow range of fraction. On the micrographs of Fig. 3a), b) and c) morphology of blends when the third polymer is random copolymer with the same monomeric units as one of the homopolymer can be seen. The effect of fraction of random copolymer on morphology and effect on the dimension of dispersed domains is obvious. On the same micrographs it can be observed the third polymer that encapsulate the minor dispersed phase that is noticed as white border of phases on micrographs of Fig 3a) and c). On SEM Micrographs Fig 4a) b) c) and Fig 5a) b) c) it can be also noticed different morphology by changing the concentration of polymers in ternary component blends. From the results can be concluded that the third polymer used as compatibilizer can enhance miscibility of two immiscible polymers by making a new interphase. Fraction of compatibilizer has shown an influence on type of morphology in blend as well.