Effect of blend ratio on thermal, mechanical, and shape memory properties of poly (lactic acid)/thermoplastic polyurethane bio-blends

The increase in surgical interventions and the need for rapid patient recovery have sped up biomaterials research. Materials for sutures that feature shape memory properties prevent the opening of surgical stitches and accelerate wound healing and patient recovery. Shape memory polymers (SMP) are stimuli-responsive materials that can recover to their original shape, for example, non-strained, after some external stimulus, as the temperature can be used for thermo-responsive SMP. Poly (lactic acid) (PLA)/thermoplastic polyurethane (TPU) bio-blends have shape memory properties and can be an excellent choice of biomaterial for use in this area. In this work, PLA/TPU bio-blends with different blend mass ratios (100/0, 90/10, 80/20, 70/30, 60/40, 50/50, 40/60, 30/70, 20/80, 10/90, and 0/100) were prepared using a twin-screw extruder and the effect of blend ratio on the mechanical (tensile tests and Izod impact strength), thermal, morphological, rheological and shape memory properties of PLA/TPU bio-blends were evaluated. PLA/TPU bio-blends presented a dispersed phase morphology of the lower content component. A decrease in the degree of crystallinity of the PLA phase was observed for the PLA/TPU blends with the increase of the TPU phase. PLA/TPU bio-blends with higher TPU contents showed better shape recovery, highly prized property in SMP, and increased recovery temperature positively and directly affected this property. PLA/TPU (30/70) presented the best results for the use in sutures lines and passed the self-tightening knot test, with an elongation at break of 80% and a shape recovery ratio of 40%.