Rheological properties of dynamically vulcanized poly(vinyl chloride)/epoxidized natural rubber thermoplastic elastomers: effect of processing variables

The melt rheological behavior of poly(vinyl chloride)/epoxidized natural ru bber (PVC/ENR) thermoplastic elastomers (TPEs) was studied with a special r eference to the effect of dynamic vulcanization, apparent shear rate and te mperature using a twin screw capillary rheometer. PVC/ENR TPEs were compoun ded with a HAAKE twin screw extruder (WCT100). At a particular temperature it was found that the apparent viscosity decreased with increased in appare nt shear rate following a pseudoplastic behavior, thus indicating that the dynamically vulcanized TPEs are processible as thermoplastics. The elastic phenomena was investigated by calculating the die swell which was found to be affected by the apparent shear rate and processing temperature. The extr udate surfaces at different apparent shear rates were studied by means of o ptical microscopy. It was observed that as apparent shear rate increases th e extrudate surface exhibits a higher degree of deformation, the extent of which is also dependent on the sulfur concentration. (C) 1999 Elsevier Scie nce Ltd. All rights reserved.