Thermally Stimulated Shape Memory Character of Radiation Crosslinked Polyolefinic Blends

Abstract

Shape memory property of polymeric materials is defined as a property that enables the polymeric materials to remember their permanent shape, when it is deformed to a temporary shape in presence of an external stimulus, such as light, chemicals, electric or magnetic field, pH of the medium, heat. In this chapter, thermally stimulated shape memory character of various polyolefinic blends mostly ethylene octene copolymer (EOC) and ethylene propylene diene terpolymer rubber (EPDM)-based blends has been demonstrated by the authors. A comparative study of the shape memory behavior of EOC-EPDM blends, both in the un-crosslinked state and radiation crosslinked state, has been focused. Compared to the un-crosslinked blend, the shape fixity behavior of the crosslinked blends becomes inferior due to the destruction of the crystalline structure of the polyolefinic backbone. On the other hand, the shape recovery behavior of the electron beam crosslinked blends becomes better due to the formation of the crosslinked network structure. Atomic force microscopic study and percentage gel content value support the formation of crosslinked network structure in presence of electron beam treatment whereas the X-ray diffraction analysis and differential scanning calorimetry study suggest the destruction of the crystalline structure of the polyolefinic backbone after the electron beam irradiation.