Preparation and characterizations of thermoplastic elastomer based on maleated polyolefin elastomer (mPOE)/nylon11 blends and its nanocomposites with graphene

Abstract

Semicrystalline maleated polyolefin elastomer (mPOE) and nylon 11 were melt blended in an internal mixer at 200oC with proportions of 90/10, 80/20, 70/30, and 60/40 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 11 copolymer was formed during the mixing, and the blends showed that two melting transitions at 58~60oC and 181~185oC were attributed to mPOE and nylon 11, respectively, which are depending on the blend composition. The blends exhibited the typical thermoplastic elastomeric behavior and their tensile modulus and strength increased with increasing the nylon content. It was also observed that the blends formed a physically-crosslinked structure until the melting transition of nylon 11 occured. The blends exhibited an excellent thermally-triggered shape memory effect, i.e., almost 100% shape fixity rate and 100% shape recovery rate, and the recovery occurred in a few seconds when the temporarily fixed shaped sample was heated just above the Tm of mPOE phase in the blends. Small amount of thermally-reduced graphene oxide (TrGO) was incorporated into a mPOE/nylon 11(70/30) blend by a melt blending process. The TrGO is uniformly dispersed at nanometer scale in the matrix elasomter. Enhanced mechanical properties of the nanocomposites without accompanying any loss of elastic recoverability and elongation-at-break of the matrix elastomer were observed from tensile and dynamic mechanical testing. Oscillatory shear controlled rheology in the molten state of the nanocomposites showed a pseudo solid-like behavior as well as an enhanced shear thinning behavior. Furthermore, the nanocomposites showed IR triggered shape memory effect, i,e, the recovery for a nanocomposite with 1.0 wt% TrGO occurs within 10 min when the temporarily fixed shaped sample was exposed to near IR.