Shear flow behavior and oil distribution between phases in thermoplastic vulcanizates

Abstract

ABSTRACT:The high rate shear flow behavior and the morphology of five different oil-extended polypropylene (PP)/ethylene-propylene-diene monomer (EPDM) thermoplastic vulcanizate blends were investigated with the melt flow rate (MFR) of the PP varying from 0.7 to 20. The ratio of rubber to PP is 70 : 30 in three of the thermoplastic vulcanizates (TPVs) and 50 : 50 in the other two TPVs. The distribution of the high-temperature oil between the PP melt and the rubber is a key parameter because this will affect the viscosity of the PP/oil medium. The object of this study was to estimate the matrix composition in each of the TPVs at processing temperatures and to compare the shear viscosity of the effective matrix with that of the TPV. To this end, several PP/oil mixtures were prepared and their viscosity curves were correlated with the neat PP melt viscosity curves by means of shift factors varying with oil concentration. The oil distribution between the PP and rubber phases was estimated from TEM micrographs of the TPV blends. The results show that the PPs are mixed with oil to different proportions in the different TPVs and the viscosity curves of these mixtures exhibit the same trends in magnitude as the corresponding TPV viscosity curves. Hence, the shear flow of TPVs can be understood more readily in terms of the effective PP/oil medium flow behavior than in terms of the neat PP melt flow.

Rheological, mechanical and morphological properties of thermoplastic vulcanizates based on high impact polystyrene and styrene‐butadiene rubber

“…Although TPVs have been extensively used in industry, few papers have been published to address their rheological behavior. The first investigation on the rheological properties of TPVs was performed by Goettler et al15 In recent years, the melt flow behavior of TPEs produced by the dynamic vulcanization of rubber/plastic blends has received much attention, and the rheological behavior of the TPVs has been studied using plate–plate and capillary rheometers 16–20. Usually, TPVs exhibit non‐Newtonian viscosity and the molten TPVs behave like the particle filled polymer melts.…”

Polypropylene/natural rubber thermoplastic elastomer: Effect of phenolic resin as a vulcanizing agent on mechanical properties and morphology

“…Natural rubber (NR) has been used to blend with polyethylene to prepare TPEs 10–12. Although PP/EPDM TPV is already commercialized, namely Santoprene (TPV prepared from PP and EPDM still has been extensively studied 13–24. Development in morphology and mechanical properties of PP/EPDM TPV were reported in many articles 13, 15–17, 19, 20.…”

Polypropylene/Ethylene–Propylene–Diene Terpolymer Blends

“…The Ellul group reported the shear flow behavior and oil distribution between phases in TPVs (55). The distribution of the high temperature oil between the PP melt and the EPDM was a key parameter because this affected the viscosity of the PP/oil medium.…”