Heat Degradation of AS Resin upon Heat-process Cycles

Abstract

In order to investigate the heat-degradation of AS resin upon heat-process cycling, several kinds of heat-treated AS samples were prepared by using a hot-pressing or a single-screw extruder, and then, their chemical and/or physical properties were examined. From the results of FT-IR spectrum, it was found that the absorption of C = O group were measured and its intensity increased with heat-process cycles. Such an absorption peak, however, cannot be observed on the samples treated in N₂. The molecular weight of the samples decreased with annealing time, and their decline ratios were increased by rising the heat-process temperature. At the same temperature, the molecular weight decline ratios depended only on the heat-process cycle numbers, and not change in spite of the screw speed of the extruder. In N₂ atmosphere, however, the molecular weight decline ratios were suppressed about 50% to be compared with that in the air. Although Young’s modulus (E) obtained by stress-strain curves for the heat-process cycled AS samples with their molecular weight (Mw) more than 10,000 were almost the same, the values of E for the heat-recycled AS samples with Mw less than 10,000 decreased with its molecular weight.