Change of Degradation Properties after Pelletizing of Soft Polyvinyl Chloride Dry Powder Blend by Melt Compounding
In current study, degradation properties of soft PVC dry powder blends were investigated before and after plasticating extrusion compounding by means of a torque rheometer as well as extent of discoloration. The powder blend was prepared thorough hot and cold mixing method. Before pelletizing by means of plasticating extrusion compounding, the PVC powder composite exhibited longer stability time. On the other hand, melt compounded pellets exhibited shorter stability and faster discoloration than that of powder blends. It was observed for the current PVC system that filling torque value is much higher for the granulated pellet samples than its dry blend form. The difference between discolorations increased as the heat duration increased during heat processing. The difference for the stability time obtained from the measured rheogram was 10.30 minutes for the processing temperature value of 180 °C between dry powder blend and corresponding compounded pellets. It is concluded from the current work that pelletizing by melt compounding the studied PVC dry blends causes degradation changes in the PVC composites as it facilitates the dehydrochlorination process of the polymer. However, the PVC dry blend form has longer stability during PVC heat processing.
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