Investigation of mechanical behavior of epoxy shape memory polymers

Abstract

Shape memory polymer (SMP) is a new class of smart material which attracts great interest in recent years. In this paper, in addition to the synthesizing of three types of epoxy SMPs with various linear epoxy monomer contents, their mechanical properties are focused on. Structure characteristic, dynamic mechanical property and quasi-static tension property and shape memory behavior of the epoxy SMPs are presented. Results indicate that glass transition temperature determined by dynamic mechanical analysis (loss modulus) varies from 69 to 113 °C for the epoxy SMPs. And it should be noted that the linear monomer has no effect on storage modulus in glass state but decrease the storage modulus in rubber state for the polymers. From tensile test, it is found that the content of linear monomer has significant effect on the tensile deformation behavior which varies from a brittle response to elastomeric response at room temperature. And the strength varies from 15 to 62MPa with the corresponding elastic modulus ranging from 2.5 to 1.7GPa for the epoxy system. Characterization of the shape memory effect in epoxy SMP suggests a high (above 99%) shape recovery ratio at 100 °C, besides, the epoxy SMP with higher linear monomer content shows a quicker shape recovery speed. Moreover, effect of linear monomer content on glass transition temperature and thermo-mechanical property is also investigated. Results indicate that, epoxy SMP fabricated in this study possess not only unique shape memory effect but also excellent mechanical properties, which will be the leading candidate for applications in engineering fields.