Compatibilization Modification Of PLLA/PBAT With Cellulose Nanocrystals Powder And Its 3D Printing Application

Compared to traditional manufacturing techniques,3D printing has become a hot topic due to its efficiency,simplicity,and flexible design.The combination of 3D printing technology with shape memory polymers in 4D printing has resulted in a new breakthrough.Poly L-lactic acid(PLLA)is a biodegradable polymer with excellent properties such as high strength,high modulus,and biocompatibility,as well as good shape memory performance.However,its drawbacks such as brittleness,poor toughness,and low melt strength limit its applications.Poly butylene adipate-co-terephthalate(PBAT)is a complementary biodegradable material to PLLA with high elongation and melt strength,but lower strength and modulus.Blending PLLA and PBAT can achieve complementary advantages,reduce costs,and improve overall performance.However,their inherent immiscibility limits further enhancement of their performance.The combination of biopolymer blends and biobased nanofillers is an effective strategy to achieve high-performance polymer alloys with a multi-level structure,while maintaining their full biobased and biodegradable properties.However,achieving good dispersion of hydrophilic nanocellulose materials in hydrophobic polymer matrices using traditional processing methods such as melt blending and melt extrusion remains a challenge.In this study,a simple melt extrusion process successfully achieved uniform dispersion of cellulose nanocrystals modified with polyvinyl acetate(CNCs-PVAc)powder synthesized by a one-pot method in PLLA/PBAT blends,producing environmentally friendly nanocomposites with full biodegradability,biocompatibility,high melt strength,and excellent shape memory properties.The PLLA/PBAT/CNCsPVAc nanocomposite was further processed by melt extrusion to produce filaments for3 D printing,and its printability characteristics,surface roughness,rheological properties,thermodynamic properties,mechanical properties,phase morphology,biodegradability,biocompatibility,and shape memory performance were investigated.The relationship between the composition of CNCs-PVAc,the content of CNCsPVAc,the method of melt processing,and thermodynamic and kinetic factors and the structure of the nanocomposite,dispersion of the nanoparticles,and mechanical and shape memory properties of the composite was systematically studied,and the mechanism of CNCs-PVAc reinforcement and compatibilization of PLLA/PBAT blends was explored.The study showed that during the Fused Deposition Modeling(FDM)process of 3D printing,the synergistic effect of CNCs-PVAc and strong shear force field led to the formation of highly oriented PBAT nanofiber structures in the PLLA/PBAT/CNCs-PVAc nanocomposite,which helped achieve a strong-tough balance in 3D printed parts.Combined with the excellent biodegradability,biocompatibility,mechanical,and shape memory properties of the nanocomposite,medical vascular clips and strong-tough load-bearing structures were designed and printed.This work further revealed the structure-property-application relationship during FDM-3D printing and provided an effective method for preparing high-performance,green,biobased nanocomposites for FDM-3D applications.