Preparation of thermo-responsive shape memory copolyester thermoplastic elastomer (COPE) and poly(ethylene-co-vinyl acetate) polymer blends

Abstract

 Preparation of COPE/EVA blend through melt mixing  Determination of shape memory properties  Effect of composition on morphologyShape memory polymers (SHP) are smart materials that can change their shape when stimulated with an external stimulus such as heat, humidity, magnetic field and electric field. Thermo-responsive shape memory polymers have the ability to change their temporary shape with their permanent shape when they are exposed to an external heat stimuli and this ability gives them great potential for sensor, actuator, medical and packaging applications. Thermally sensitive shape memory polymers need at least two functional components. One of them is the switch component and it is responsible for fixing the temporary shape. The other component is the elastomeric component and it provides required driving force to recover the permanent shape. In this study, thermo-responsive shape memory copolyester thermoplastic elastomer (COPE) and poly (ethylene-co-vinyl acetate) (EVA) polymer blends were prepared and their shape memory characteristics were investigated. Figure A.Thermo-mechanical graph of the 50C-50E blend and photographs of shape memory behavior.Purpose: The aim of this study is preparation of novel thermally responsive shape memory COPE/EVA polymers blends and report their characteristics.Theory and Methods: COPE/EVA polymer blends were prepared through melt mixing of switch component EVA and elastic component COPE. Morphological, thermal, mechanical and shape memory properties of the prepared blends were investigated. Results:Scanning Electron microscopy (SEM) analysis showed that the polymer blend containing 50 wt% COPE and 50 wt% EVA showed co-continuous morphology, while other compositions were found to exhibit droplet morphologies. Among the blends, the 30C-70E exhibited 94.88% shape fixing ratio and 89.20% shape recovery ratio. On the other hand, 50C-50E blend with relatively higher deformability, showed the optimum shape fixing and recovery ratios.The shape memory analysis of the 50C-50E polymer blend in hot water showed that after the material was deformed and cooled, it retained its temporary shape, and when it was reheated, it quickly returned to its permanent shape. Conclusion:Novel thermally responsive shape memory COPE/EVA polymer blends were produced via melt mixing method. According to the thermo-responsive shape memory property analyses, the shape fixing (Rf) and shape recovery (Rr) ratios were increased when the amount of EVA increase in the polymer blend.