Impact of cryogenic treatment on mechanical and electro active actuation properties of soft polymers

Abstract

The goal of this study is to investigate the change in stretchability property of soft polymers before and after cryogenic treatment. To achieve this, the influences of cryogenic treatment on the rate dependent tensile properties, hysteresis behavior, and stress‐relaxation of soft polymers are extensively analyzed. Results indicated that the effects of cryogenic treatment for both VHB and Ecoflex samples on mechanical responses were more prominent at low strain rate. It was also observed that VHB polymer could exhibit more strain rate sensitivity than Ecoflex sample after cryogenic treatment. For stress relaxation test, both cryo‐treated polymer samples were found to yield less overall stress and takes longer time to reach equilibrium stress in comparison to untreated polymer. Extensive experimental findings showed that the amount of energy dissipated while cooling below glass transition temperature (Tg), causes stress softening with lowering of viscoelastic property. On the other hand, there is a good enhancement of the electro‐active actuation strain for the cryo‐treated VHB 4910 and Ecoflex specimens. The results of this work could be used as a helpful guide for applying cryogenic treatment to improve electro‐mechanical properties of soft polymers, as the theory underlying this treatment has not been well explored