Supramolecular semicrystalline polyolefin elastomer blends with triple-shape memory effects

Abstract

Supramolecular polyolefin elastomer blends possessing triple-shape memory effects were prepared by melt blending of two semicrystalline maleated elastomers (maleated ethylene-propylene-diene rubber (mEPDM) and maleated polyethylene-octene elastomer (mPOE)) in the presence of a small amount of 3-amino-1,2,4-triazole (ATA). The amino group of ATA reacted with the maleic anhydride groups of both elastomers during melt blending to form supramolecular hydrogen-bonded networks. Dynamic mechanical analysis of the blends showed drops in the storage modulus at two different transition temperatures (T-trans) belonging to the crystalline melting temperatures of each phase as well as a plateau above these two T-trans. This is an essential property for triple-shape memory behavior. Dual-shape memory properties of the blends were determined using one-step programming under three different temperature ranges. When an individual crystalline phase is used for the fixing process, the switching temperature (T-sw) relates to the melting temperature of a particular phase during the recovery process. However, if both crystalline phases are used simultaneously for the fixing process, then the T-sw relates to the higher melting temperature. Cyclic two-step programming revealed that two different shapes can be fixed, one by EPDM crystallization and the other by POE crystallization, and both programmed shapes can be recovered upon heating above a specific T-sw. (c) 2016 Society of Chemical Industry