High-Strength Triple Shape Memory Elastomers from Radiation-Vulcanized Polyolefin Elastomer/Polypropylene Blends

Abstract

High-strength and high-temperature triple shape memory elastomers from multiphase polyolefin elastomer (POE)/polypropylene (PP) blends are prepared via radiation-induced vulcanization. Irradiation generates cross-linking mainly in the amorphous sequences of POE chains, long chain branches in the amorphous regions of PP crystals, and grafting between PP and POE chains at the interface of the POE and PP phases. The discoid-like PP phase with an average size of 1.6 × 11 μm2, dispersed in the POE matrix, is aligned parallel to the plane of the recompressed films. The PP lamellar crystals is partially orientated, and the PP lamellar crystals with (040)α and (110)α planes are arranged parallel and perpendicular to the surface of the highly cross-linked films, respectively. The integration of heterogeneous macromolecular structure, partially orientated crystals, and separated multiphase morphology contributes to excellent triple shape memory effects and high tensile strength up to 38 MPa. Consequently, two temporary shapes with fixity ratios of 82 and 97% are programmed by the reversible aggregation and solidification of the segregated PP lamellar crystals and POE bundle-like crystals. Under thermal triggering at the switching temperatures of 90 and 180 °C, the entropy-driven elasticity of the discrete PP and POE switching segments provides a good shape recovery of 88 and 94% to the memorized complex permanent shape. These results indicate that designing and tailoring the unconventional macromolecular architecture and condensed-state structure provide a novel strategy for developing low cost, high performance, and flexible intelligent polyolefins.

Controlling the mechanoadaptive properties of hydrogenated nitrile rubber by the incorporation of cementious based industrial waste for downhole application

“…The 28‐day SAXS data also shows more scattering, which in turn reflects the interaction between the filler and the matrix. [ 47 ] The cyclic loading and unloading at 100% strain of the samples were done at 500 mm/min for six cycles, and the stress difference between the first and sixth (last) cycle was plotted in Figure 6D.…”

Smart TPE Materials Based on Recycled Rubber Shred

“…Currently, the structural design of SMPs can be achieved by grafting [ 31 ], copolymerization [ 14 , 32 ], formation of interpenetrating polymer networks (IPNs) [ 33 , 34 ], or blending of polymers and rubbers [ 35 , 36 , 37 , 38 , 39 ]. They all aim to obtain a multiphase material exhibiting at least two different transition temperatures.…”

“…EPDM/PP blends with an interface modified by the addition of magnesium acrylate showed the shape fixity ~90% and shape recovery ~92.5% [ 38 ]. Thermoplastic polymers such as polyethylene [ 36 ] or polypropylene [ 37 ] were directly mixed with thermoplastic elastomers to obtain shape memory materials. Moreover, polyethylene/polycyclooctene blends crosslinked by electron irradiation showed excellent shape memory performance with strain fixity and strain recovery ratio of 95–99% [ 36 ].…”

A Facile Approach toward Thermoplastic Triple‐Shape Memory Polymers

“…Such a high value is comparable to that of the crosslinked shape memory PU and POE. [ 27,28 ] Therefore, the incorporation of crystalline PCL and LA together into the elastomer in this work endowed the material with not only a triple‐SME, but also a high level of toughness. This will be a plus for practical applications.…”