Shape memory thermoplastic elastomer from maleated polyolefin elastomer and nylon 12 blends

Abstract

Semicrystalline maleated polyolefin elastomer (mPOE) and nylon 12 were melt blended in an internal mixer at 200 A degrees C with proportions of 90/10, 80/20, and 70/30 wt/wt, respectively. Molau test, melt viscosity measurement, differential scanning calorimetry, dynamic mechanical analysis and tensile testing were conducted to characterize the structure and properties of the blends. The results revealed that POE-graft-nylon 12 copolymer was formed during the mixing, and the blends show two melting transitions at 57-60 and 174-178 A degrees C attributed to mPOE and nylon 12, respectively, which are dependent on the blend composition. The blends exhibit typical thermoplastic elastomeric behavior and their tensile modulus, strength and hardness increase with increasing nylon content. It was also observed that the blends form a physically crosslinked structure until the melting transition of nylon 12. The blends exhibit excellent thermally triggered shape memory effect, i.e., almost 100 % shape fixity rate and 100 % shape recovery rate, and the recovery occurs in a few seconds when the temporarily fixed shaped sample is heated just above the T (m) of mPOE phase in the blends.