Thermal actuation shape memory of ultra-high-molecular-weight polyethylene (UHMWPE) with molecular orientation

• Preparation of shape memory UHMWPE/HDPE samples with molecular orientation. • Cyclic tensile shape memory property of UHMWPE/HDPE samples. • Movement and evolution of chain segments in shape-changing process. Conventional compression-molding method cannot illustrate the effect of molecular orientation on shape memory property. Herein, high-density polyethylene (HDPE) is incorporated into ultra-high-molecular-weight polyethylene (UHMWPE) to prepare samples with molecular orientation by the single screw extrusion and traction machine. Interestingly, the shape recovery rate (R r ) of samples with the same tensile direction as molecular orientation decreases from 66.13% to 60.71% with the traction rate, while the R r of samples with tensile direction perpendicular to molecular orientation exhibits an opposite tendency in cyclic tensile shape memory tests. Meanwhile, the shape fixation rate of these two samples does not change significantly. In addition, the possible mechanism of thermal actuation shape memory of samples with molecular orientation is interpreted.