Mechanical properties of poly(vinyl chloride) of defined gelation degree

The effect of processing temperature (140-205 °C) on gelation degree (G) of unplasticized PVC of K value = 61, containing 8 wt. % of ethylene/vinyl acetate copolymer, has been studied using three various measuring tools: weight plastometer, capillary rheometer and screw capillary rheometer. It was found that independently on the method used all of measuring points lay on the one curve. The dependence of G value on the composition of the mixture of non-gelated (A) and fully gelated (B) PVC granulated products in the whole range of their compositions has been determined using the methods mentioned above. The following properties of the extrudates were tested: impact strength, tensile strength and relative elongation at break. There was found the possibility of determination of mechanical properties of an extrudate via proper selection of processing temperature and the composition of PVC granulated products, showing various gelation degrees.