Heat Degradation of Poly(styrene) in Extruding Cycles 2
Effects of Molecular Weight

Abstract

Poly(styrene) samples (MW1C and G100C) were reprocessed in multiple cycles by a single-screw extruder. The reprocessed heat degraded samples were characterized by dynamic viscoelasticity and stress-strain measurement.
When the temperatures of heat degradation and the volume velocity of extrusion were particularly selected, the molecular weight (M_η) for the heat degradation samples was expressed by the time (t) required in extrusion without depending on original molecular weight. In blend system, the decrease in M_η was expressed by similar relationship for homo-system, suggesting that the synergy effect of blend on the heat degradation was neglected. Young's modulus (E) obtained from stress-strain curves did not change for both the virgin and the heat degraded samples. It is important to reprocess at temperature (T) as low as possible in order to increase the cycles number (n)