Influence of epoxide content and blend ratios on strength and damping properties of thermoplastic vulcanizates based on epoxidized natural rubber and poly(ether-block-amide) copolymer blends
Azizon Kaesaman, Rawviyanee Romin, Charoen Nakason
Vol. 17., No.10., Pages 1056-1069, 2023
DOI: 10.3144/expresspolymlett.2023.79
DOI: 10.3144/expresspolymlett.2023.79
Corresponding author: Charoen Nakason 
GRAPHICAL ABSTRACT
ABSTRACT
Epoxidized natural rubber (ENR) with varying levels of epoxide groups ranging from 10 to 50 mol% was prepared and dynamically phenolic vulcanized by blending it with poly(ether-block-amide) copolymer (PEBA). The results indicate that the thermoplastic vulcanizates (TPVs) of ENR/PEBA blends display a sea-island morphology and enhance a number of properties. Specifically, increasing the epoxide content and PEBA proportion enhances strength properties, including higher Young’s modulus (stiffness), toughness, tensile properties, and hardness, along with smaller vulcanized ENR domains dispersed in the PEBA matrix. Moreover, the decrease in tension set values indicates an improvement in the elastic properties. The attributed cause of this is the interaction between the polar groups present in the phenolic-cured ENR domains and the PEBA molecules. As a result, interfacial adhesion between the ENR domains and PEBA interfaces improved, contributing to the observed enhancements in the strength and elastic properties of the TPVs with smaller ENR domains. Furthermore, an increase in the epoxide content was found to be correlated with a decrease in tanδ and tension set, which further supported the observed improvements in strength and elasticity. Additionally, the ENR/PEBA blends showed a single glass transition temperature (Tg), while pure PEBA exhibited two Tgs. The presence of a single Tg in the ENR/PEBA blend is attributed to the overlapping of the Tg of the ENR and PEBA immiscible blend components.
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