Effect of Rubber Nanoparticle Agglomeration on Properties of Thermoplastic Vulcanizates during Dynamic Vulcanization.

Hanguang Wu,Ming Tian,Nanying Ning,Hongchi Tian,Liqun Zhang,Guo-Hua Hu,Youping Wu

doi:10.3390/polym8040127

Abstract

We previously reported that the dispersed rubber microparticles in ethylene-propylene-diene monomer (EPDM)/polypropylene (PP) thermoplastic vulcanizates (TPVs) are actually agglomerates of rubber nanoparticles. In this study, based on this new understanding of the microstructure of TPV, we further revealed the microstructure-properties relationship of EPDM/PP TPV during dynamic vulcanization, especially the effect of the size of rubber nanoparticle agglomerates (dn), the thicknesses of PP ligaments (IDpoly) and the rubber network on the properties of EPDM/PP TPV. We were able to simultaneously obtain a high tensile strength, elongation at break, elastic modulus, and elasticity for the EPDM/PP TPV by the achievement of a smaller dn, a thinner IDpoly and a denser rubber network. Interestingly, the effect of dn and IDpoly on the elastic modulus of EPDM/PP TPV composed of rubber nanoparticle agglomerates is different from that of EPDM/PP TPVs composed of rubber microparticles reported previously. The deformation behavior of the TPVs during stretching was studied to understand the mechanism for the achievement of good mechanical properties. Interestingly, the rubber nanoparticle agglomerates are oriented along the tensile direction during stretching. The TPV samples with smaller and more numerous rubber nanoparticle agglomerates can slow down the development of voids and cracks more effectively, thus leading to increase in tensile strength and elongation at break of the EPDM/PP TPV.

Highlights

Thermoplastic vulcanizates (TPVs) are a group of high performance thermoplastic elastomers with a high content of crosslinked rubber as the dispersed phase and a low content of thermoplastics as the continuous phase [1]
thermoplastic vulcanizates (TPVs) are produced by dynamic vulcanization (DV), a complicated reactive blending process consisting of the breakup and crosslinking of the rubber phase and the phase inversion of the rubber and the thermoplastic, dominating the formation of phase structure including the rubber particle size, the rubber network, and the thicknesses of the matrix ligaments [1]
With the new understanding of the morphological evolution of TPV, we further studied the effect of rubber nanoparticle agglomerates (RNAs) on the properties of TPV during DV and the microstructure-properties relationship of ethylene-propylenediene monomer (EPDM)/PP TPV during DV, especially the effect of the size of RNAs, the thicknesses of PP ligaments (IDpoly ), and the density of the rubber network on the properties

Summary

Introduction

Thermoplastic vulcanizates (TPVs) are a group of high performance thermoplastic elastomers with a high content of crosslinked rubber as the dispersed phase and a low content of thermoplastics as the continuous phase [1]. TPVs combine the high elasticity of conventional vulcanized elastomers and the high processability and recyclability of thermoplastics. TPVs are some of the fastest growing elastomers because of the requirement of environmental protection and resource savings [2]. TPVs are produced by dynamic vulcanization (DV), a complicated reactive blending process consisting of the breakup and crosslinking of the rubber phase and the phase inversion of the rubber and the thermoplastic, dominating the formation of phase structure including the rubber particle size, the rubber network, and the thicknesses of the matrix ligaments [1].

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