THERMAL AGING OF AND BISPHENOL-A POLYCARBONATE ACRYLONITRILE-BUTADIENE-STYRENE BLENDS

Thermal aging of immiscible bisphenol-A polycarbonate/acrylonitrile-bu tadiene-styrene (PC/ABS) blends containing 25, 60, and 75% PC and the PC and ABS blend components have been studied. Changes in Izod impact properties and dynamic mechanical spectra are reported following aging at 90, 110, and 130 degrees C for times up to 1500 h. PC/ABS blends c ontaining 60 and 75% PC were found to retain high impact performance f ollowing aging at elevated temperatures, compared to the PC blend comp onent. Dynamic mechanical spectroscopy is an effective probe for inves tigating the structure-property changes occurring and the mechanisms o f aging. For PC and ABS, the changes were mainly due to physical aging of the amorphous polymers when aged below the glass-transition temper ature. For the PC/ABS blends, oxidative degradation additionally contr ibutes to loss of toughness. Although structure-property changes are r elated to the behavior of the blend components, additional factors of potential importance for multiphase polymer-polymer systems have been identified, including a redistribution of stabilizers during the blend manufacture. (C) 1995 John Wiley & Sons, Inc.