Electron beam irradiation cross-linked PP/LDPE blends with triple-shape memory capabilities

Abstract

Recently, thermoplastic materials with triple-shape memory capabilities have attracted increasing interest due to their promising applications. In this study, we introduce a facile and novel method of post-electron beam irradiation cross-linking to fabricate semi-crystalline, T_m-type triple-shape memory polymeric materials of polypropylene (PP)/low-density polyethylene (LDPE) blends. Gel fraction analysis, differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), tensile testing, rheological measurements, field emission scanning electron microscopy (SEM) and dynamic mechanical thermal analysis (DMTA) were systematically conducted to investigate the correlation between the structure and properties. The results suggest that significant triple-shape memory effects can be observed in the 100 kGy irradiated PP/LDPE (50/50) blends with co-continuous architectures, demonstrating relatively high values of shape fixity ratio (76.7% and 89.5%) and shape recovery ratio (94.5% and 81.8%). Finally, we propose an enhanced 3D shape memory polymer (SMP) architecture model to provide a comprehensive understanding of the molecular mechanisms underlying the triple-shape memory capacity.