THE PHYSICO-MECHANICAL AND MORPHOLOGICAL PROPERTIES OF -CELLULOSE-FILLED POLYSTYRENE (PS) AND POLYVINYL ACETATE (PVAc) BLENDS

Studies of physico-mechanical and morphological properties of pure and -cellulose reinforced blends of polystyrene (PS) and poly (vinyl acetate) (PVAc) are reported in this work. The compression moulded articles of the blends of different compositions (10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20 and 90:10, PS/PVAc) were tested for mechanical performance, absorption behaviour, void activity and morphological arrangements. Comparison of mechanical properties such as tensile strength, modulus of elasticity and elongation at break revealed apparent compatibility domains for 20:80 and 10:90, PS/PVAc for both pure and reinforced blends. However, the - cellulose filled blends have enhanced tensile strength for all the compositions. From the values of the breaking load (in kilonewtonsKN) Vs composition of the blends, there was considerable strength improvement with -cellulose filler content. The equilibrium sorption in four different solvents, showed a declining order in accordance to acid > water > base > acetone. However, solvent absorption increased with filler content in all the solvents, because the filler increased the gelation level, hence the sorption rise except in acetone which showed a sharp reduction in % absorption in the presence of -cellulose filler. The acetone seems to dissolve the crystalline portion of the blends and cannot be used to detect the differences between the polymer blends xvi and their molecular structure. The void activity in the blend were estimated by density measurements, and they showed a definite pattern except that the filler increases the densities of the blends 30/70, 20/80, and 10/90, PS/ PVAc having the highest values than other compositions. Also, photo micrographs of the certain blends showed a two phase system appearing bright (PVAc phase) and the other appearing opaque (PS phase) in virtually all the micrographs, even though the heterogeneity due to phase inversions (phase changes) was relevant for some compositions. For other compositions, a domain distribution showed considerable miscibility within the range of compositions.