Mechanical and flammability properties of ABS/PVC blends

Abstract

Blending of polymers is often used as a means to develop new materials with the desired properties. The main objective of this research is to study the effect of different PVC molecular weight (K-58 and K-66) and acrylic grafted PVC on different grades of ABS in terms of mechanical and flammability properties. Morphological, thermal and rheological properties of the blends were also investigated. Three grades of ABS were used; high rigidity, medium impact and super high impact. Using a single screw extruder, blends of ABSIPVC in various compositions ranging from 100 - 80% ABS were prepared and injection moulded. Interestingly, a synergist effect is observed whereby the impact strength of the ABSPVC blends is higher than the pure polymer. With increasing PVC content, the impact strength of the blends increased. The impact strength was also found to be dependant upon PVC molecular weight, with the higher K-value, the higher the impact strength. Acrylic grafted PVC is more effective in increasing the impact strength than the non grafted PVC. The impact strength enhancement increases with increasing rubber content in the ABS. The result also shows that the highest impact strength occurs when acrylic grafted PVC was added into super high impact ABS. However, it was observed that when PVC is incorporated in ABS, there is a marginal decrease in flexural modulus. The flexural modulus of the blends was also found to be dependant upon PVC molecular weight, with the lower K-value, the higher the flexural modulus. With increasing PVC content, the flexural modulus of the blends decreased. The highest flexural modulus among the blends is high rigidity ABSI PVC K-58. The DMA study confirmed that the SAN component of ABS is highly miscible with PVC. The miscibility between SAN component of ABS has improved the interfacial adhesion between PVC and ABS. The flammability of the blends determined by the LO1 test shows that the flammability of the blends decreased with increasing PVC content. The most optimum formulation in terms of cost and mechanical properties is 80 super high impact ABS/20 PVC K-66.