The Structure of Thermoplastic Vulcanisates Based on Rubbers of Different Polarity and Polypropylene

Abstract

To expand the range of properties and the range of types of thermoplastic elastomer (TPE), materials based on ternary blends of polypropylene and polar and non-polar rubbers were produced and investigated. To obtain blended and dynamically vulcanised materials, one- and two-stage methods were tested. It was established that the best properties are possessed by composites produced using master batches (rubber mixes) based on a thermoplastic vulcanisate (TPV) rubber phase, and to improve the combination of polymers of different polarity, functionalised additives modifying the polypropylene are necessary. Optical microscopy was used to study the influence of compounding factors (the ratio of components of the polymer phase, the presence or absence of compatibilisers) and technological factors (the production method) on the structure and properties both of blended and of dynamically vulcanised TPEs. A study of the morphology of blended and vulcanised TPEs showed that, in all cases, in the polypropylene, which is the dispersion medium, there are areas rich in rubber to different degrees. Here, fragments of polar rubber are found both in the polypropylene and in zones rich in non-polar rubber, and the range of particle sizes of the disperse phase depends on the production method. The introduction of a compatibiliser leads to a considerable increase in the homogeneity of distribution of the components throughout the material, and to a reduction in the size range of the disperse phase and in the thickness of the polypropylene-rich surface layer of the extrudate (strand). In the surface layer of the strands, anisotropy of the polypropylene fibrils is observed in the direction of extrusion.