RHEOLOGICAL AND MECHANICAL-PROPERTIES OF ANTIPLASTICIZED AND RUBBER-TOUGHENED BISPHENOL-A POLYCARBONATE

The addition of a high-T-g aromatic diluent to bisphenol A polycarbona te (PC) reduced T-g and melt viscosity while raising elastic modulus a nd yield stress substantially. Ultimate tensile elongation and impact toughness were badly affected. However, the addition to these antiplas ticized blends of a small amount of a rubber modifier restored impact toughness and elongation but left the blend with increased melt fluidi ty and ambient stiffness re: neat PC. The key to this rebalancing of t he properties of PC was found to be the disappearance of the plane str ain crack instability that is a hallmark of the neat resin. The deform ation mechanism in all the rubber-containing blends in all failure tes ts, regardless of geometric constraint and strain rate was found to be shear flow alone. The large plastic zone seen at the plane strain cra ck tip appears to involve rubber particle cavitation as well. (C) 1995 John Wiley & Sons, Inc.