article

Abstract

The viscosity and processability of two olefinic thermoplastic elastomer blends are studied by capillary rheometry. The first blend type consists of PP, SEBS and paraffinic oil. These blends show co-continuous morphologies. The blend viscosity can be approached by the logarithmic addition of the viscosities of the two phases. The strands show smooth surfaces and low extrudate swell, indicating that flow instabilities are absent or suppressed. The second blend type, the thermoplastic vulcanisates (TPV), consists of cured EPDM particles dispersed in a PP matrix. These blends also contain paraffinic oil. The Herschel-Bulkley expression has been used to include yield behaviour in the flow profile in the capillary. The strands of the TPVs with high elastic behaviour (low PP or oil content) show melt fracture. The extrudate swell is low, but larger than the PP/SEBS blends, and it increases with increasing PP content.

polymer 46(17), 6391-6401, 2005

Distribution of oil in olefinic thermoplastic elastomer blends