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 .

Supramolecular thermoplastic elastomer with thermally scratch repairable effect from 3‐amino‐1,2,4‐triazole crosslinked maleated polyethylene‐octene elastomer/nylon 12 blends

“…Figure shows FTIR spectra of the neat ATA‐POE, neat nylon 12, and ATA‐POE/nylon 12 (80/20) blend. In the FTIR spectrum of neat ATA‐POE, transmittance band at 1644 and 1526 cm −1 corresponds to amide and 1552 cm −1 corresponds to asymmetric stretching vibration of carboxylate group (COO − ), can be seen . The FTIR spectrum of ATA‐POE/nylon 12 (80/20) blend shows that carbonyl group of amide is shifted from 1644 to 1640 cm −1 and carboxylate group peak at 1552 cm −1 submerged into strong peak of amide NH stretching (1558 cm −1 ) of nylon 12, in the blend because of hydrogen bonding interactions between ATA‐POE and nylon 12.…”

“…Figure shows second heating thermograms of neat ATA‐POE, neat nylon 12, and ATA‐POE/nylon 12 blends. Neat ATA‐POE shows two endothermic peaks; one at around 60°C ( T m ) related to melting transition of POE crystals and second at around 156°C ( T h ) corresponds to melting temperature of free ATA, whereas mPOE has melting temperature of 63.7°C . All the blends show another endothermic peak at around 163°C ( T n ) due to the melting transition of nylon 12.…”

“…ATA‐POE was prepared first by melt blending of mPOE with 10 phr of ATA at 180°C for 5 min in an internal mixer, as reported in our previous article . Then, nylon 12 was melted for 2 min and ATA‐POE was added.…”

“…In our previous article, we observed that crosslinking of maleated polyethylene–octene elastomer (mPOE) having small amount of crystallinity with 3‐amino‐1,2,4‐triazole (ATA) can produce supramolecular TPE with thermally triggered scratch repairing ability as well as shape memory effect. It was thought that the scratch repairability of this TPE is attributed to both supramolecular hydrogen bonding interactions between the elastomer chains and shape memory effect.…”

A modified phase‐based constitutive model for shape memory polymers

“…Shape memory polymers (SMPs) are a type of smart materials that are able to fix a temporary shape and then return to their permanent shape by an external stimulus such as temperature, light, electricity and humidity . Compared to shape memory ceramics and shape memory alloys, SMPs have many special advantages, e.g.…”