EFFECT OF BLENDING SEQUENCE ON THE MODULUS, TOUGHNESS, AND STRUCTURE OF PC/PBT/TALC TERNARY COMPOSITES

摘要

Ternary blends based on polycarbonate (PC), poly[butylene terephthalate] (PBT), and talc are typically mixed in one step having a talc composition in the range of 6-12% by weight. This gives rise to flexural properties in the range of 3 GPa and lower thermal expansion which is advantageous for the production of exterior body panels but the high talc loading levels also significantly reduce the impact strength (toughness) and add to the overall weight of the composite. In an effort to increase the toughness while maintaining flexural properties, three different blending sequences of the above ternary composite were prepared: (1) melt blend PBT with talc first and then dry blend the PC with the PBT/talc, (2) melt blend the PC, PBT, and talc in one step, and (3) melt blend PC with talc first and then dry blend PBT. It was found that the blending sequence of the ternary PC/PBT/talc composites significantly influenced the toughness while maintaining a flexural modulus of around 3.0 GPa. The ternary composites generated by blending sequence (1) showed about a 20% increase in toughness compared to blending sequences (2) and (3). The higher toughness that was observed for blending sequence (1) was attributed to keeping the talc particles primarily in the PBT phase of the composite, better dispersion of the PC and PBT phases, and less degradation of the PBT.