Study On Preparation And Properties Of Thermoplastic Polyurethane Toughened Polylactic Acid 3D Printing Materials

Polylactic acid?PLA?/Thermoplastic polyurethane?TPU?/composites with biocompatibility were prepared by melt blending.The results of scanning electron microscope?SEM?and differential scanning calorimetry?DSC?analysis showed that PLA and TPU are partially compatible.Separation between PLA and TPU results in extrusion expansion of PLA/TPU blends during extrusion.T Research of PLA/TPU composites cold crystallization found that TPU can play a nucleating agent in declining the cold crystallization activation energy??E?and semi-crystallization time(t_1/2)of PLA,raising the crystallinity?Xc?of PLA.The results of mechanical properties test showed that TPU can toughen PLA,but the toughening effect is related to the content of TPU in PLA composites.In order to improve the weak compatibility between PLA and TPU,PLA-g-GMA graft copolymer and PLA-g-TPU graft copolymer was synthesized successively.PLA/TPU/PLA-g-TPU composites were prepared by blending PLA-g-TPU graft copolymer,PLA and TPU.The compatibilization effct of PLA-g-TPU graft copolymer to PLA/TPU composites was investigated.The results of ¹H NMR test shown that GMA added into PLA is successfully grafted onto PLA,and the grafting rate can reach 9.86%when 20wt%GMA is added.FTIR measurement showed that TPU was successfully grafted onto PLA-g-GMA graft copolymer.DSC test results show that PLA-g-TPU graft copolymer can reduce the glass transition temperature?Tg?of PLA/TPU.The glass transition temperature of PLA/TPU composites can be reduced from 58.9 to 47.2 when 10wt%PLA-g-TPU was added.The addition of PLA-g-TPU graft copolymer can effectively reduce the extrusion expansion of PLA/TPU blends and improve the thermal stability of PLA/TPU blends.The mechanical test results shown that PLA-g-TPU graftcopolymer can improve the notched impact strength and elongation at break of PLA/TPU,and also can effectively improve the tensile strength of PLA/TPU.When adding 6 wt%PLA-g-TPU,the tensile strength of PLA/TPU can reach 53.4 MPa.Thermoplastic cassava starch?TPS?was prepared by mixing cassava starch with glycerol as plasticizer.PLA/TPU/PLA-g-TPU/TPS composites were prepared by melt blending TPS with PLA/TPU/PLA-g-TPU.The study of PLA/TPU/PLA-g-TPU/TPS composites shown that the represent viscosity of the composites increases gradually after adding 5-20 copies TPS,while the thermal stability and tensile strength decrease slightly.After adding 20 copeies TPS,the elongation at break and notch impacted strength of the composites are still greater than those of pure PLA.PLA/TPU,PLA/TPU/PGU?PLA-g-TPU graft copolymer?and PLA/TPU/PGU/TPS FDM 3D printing consumables were prepared.It is found that the PLA matrix composites with the above components can be used as printing consumables and successfully print out3D models.The PLA/TPU/PGU components have the best printing performance.The thermal properties of 3D printed samples were studied.It was found that 3D printing was more conducive to the crystallization of samples than injection moulding technology.The tensile strength of 3D printed samples with different filling degree was studied.It was found that the increase of filling degree was beneficial to the increase of tensile strength of samples.