Morphology Evolutions and Mechanical Properties of In Situ Fibrillar Polylactic Acid/Thermoplastic Polyurethane Blends Fabricated by Fused Deposition Modeling

Abstract

There are many studies devoted to conquer the strength–ductility trade‐off dilemma of polylactic acid (PLA) by flexible elastomer blending, like thermoplastic polyurethane (TPU), but little is known about the effects of the fused deposition modeling (FDM) process on the in situ morphology evolution of the elastomers. In this work, the effects of the three successive drawing processes in FDM on the morphology evolution of the dispersed TPU in the PLA matrix, and the toughening behavior of FDM‐printed PLA/microfibrillar‐TPU blends, are systematically studied. The results manifest that the average length of the TPU microfibrils can be turned precisely from 67.24 to 103.72 µm. The in situ microfibrillation process can remarkably improve the PLA crystallization capability and interfacial interaction. More interestingly, the inevitable decrease of impact strength of FDM‐printed part induced by the voids is compensated by the network‐like TPU microfibrils formed during the layer‐by‐layer printing. These inspiring findings suggest that the in situ fibrillation process can conquer the inherent weaknesses of both FDM process and PLA materials, providing facile and efficient method for fabricating high toughness PLA parts.

Effect of TPU hard segment content on the rheological and mechanical properties of PLA/TPU blends

“…[43] Qian et al [44] also reported that the strength and stiffness, as well as the impact strength of PLA/TPU blends, could noticeably be improved with the incorporation of 20 wt% short carbon fibers. Recently, with in situ fibrillation of TPU in PLA/TPU blends, improvements in the toughness of printed structures were reported due to the generation of TPU fibrils, enhanced PLA crystallization around the fibrillated structures, and hence improved interfacial interactions [45] Considering the long-term behavior of PLA/TPU blends, it has been reported that weathering could cause drastic losses in the strength and toughness of the blends. [46] It is still not very clear in the literature how changes in the TPU molecular structure such as variations in HS content or in the molecular weight of SS could influence the final properties of PLA/TPU blend systems.…”

Super toughened and highly ductile PLA/TPU blend systems by in situ reactive interfacial compatibilization using multifunctional epoxy‐based chain extender

“…Several studies have investigated the morphological and mechanical properties of PLA/TPU blends with and without using a compatibilizer 43–61 . Although some studies have reported that PLA and TPU are not compatible, 43–45 a few studies have shown that the ductility and impact strength of the PLA/TPU blends could be improved to some extent without the use of a compatibilizer while the strength and modulus were also decreased 44–49 .…”

Topological Structure Design and Fabrication of Biocompatible PLA/TPU/ADM Mesh with Appropriate Elasticity for Hernia Repair

“…PLA has been authorized by the Food and Drug Administration (FDA) for many clinical applications and is considered as an ideal choice for biomedical material. [ 9–12 ] However, the wide application of PLA is limited by its brittleness. [ 9,13 ] Absorbable thermoplastic polyurethane (TPU) is an ideal elastomer with mechanical properties.…”