THERMOPLASTIC-GUAYULE RUBBER BLENDS - RHEOLOGICAL PROPERTIES

In the reported experiments, an experimental study of the flow characteristics of blends of natural Guayule rubber with high-density polyethylene was carried out, and the effect of crosslinking and carbon black loading of the rubber phase was examined. It was observed that (1) an increase in shear rate decreases the viscosity and increases the extrudate swell of the blends; (2) an increase in temperature decreases the viscosity of the blends; (3) the viscosity and extrudate swell of the blends appear to be nonadditive functions of the viscosity and extrudate swell of the homopolymers and are lower than predicted by simple additivity; (4) the viscosity increases with increasing degree of crosslinking of the rubber phase; (5) the viscosity increases with increasing carbon content in the rubber phase, the increase being more pronounced when the rubber-black compound is the continuous phase; (6) when crosslinking was effected, extrudate swell varied in a very peculiar manner, which requires further study.