Preparation Of PLA/PBAT/WF Composite Material And Research On Its Fused Deposition Molding Performance

Polylactic acid(PLA)is a biodegradable thermoplastic polymer.The production raw materials are derived from renewable plant resources.At the same time,polylactic acid is one of the most widely used consumables for fused deposition modeling(FDM).However,the high strength and high modulus of pure PLA make the material poor in impact resistance,so its application range is greatly restricted.In this paper,biodegradable polyadipate/butylene terephthalate(PBAT)is used to toughen and modify PLA,and poplar powder(WF)fiber is added as a filler to improve PLA mechanical properties.PLA/PBAT is prepared/WF composite material.The characteristics of PLA and PBAT blending and the effect of WF fiber on the performance of PLA/WF composite materials were studied respectively;the fused deposition molding and performance effects of PLA/PBAT/WF composite materials modified by coupling agent were studied.(1)Melt blending with a mixer to prepare PLA/PBAT blends,using FDM technology to prepare standard experimental samples,through scanning electron microscope observation,mechanical experiments,rotational rheological testing and differential scanning calorimetry,studied The effect of different content of PBAT on the mechanical properties,rheological properties,compatibility and crystallization properties of the blend.The experiment shows that as the mass fraction of PBAT increases,the tensile strength of the blend continuously decreases,while the elongation at break shows a tendency to increase first and then decrease.When the PBAT mass fraction is 30%,the elongation at break of the blend reaches a maximum of 21.43%,and it has high tensile strength and impact strength.The addition of PBAT lowers the PLA crystallization temperature,inhibits its crystallization ability,and the crystallinity becomes smaller,thereby reducing brittleness and enhancing toughness.The greater the PBAT mass fraction in the PLA/PBAT blend,the more obvious the two-phase separation,and the greater the melt strength of the PLA/PBAT blend.(2)PLA/WF composite materials with different contents and mesh WF fibers were prepared respectively.When the WF fiber content is 10%,the maximum tensile strength of the PLA/WF composite material reaches 19.81 MPa,which is 31%higher than the pure PL A material.The WF fiber 200 mesh has the best mechanical properties.Increasing the WF fiber mass fraction will reduce the PLA crystallization temperature.WF fiber mesh has little effect on the temperature of PLA at all stages.With the increase of WF fiber content and mesh number,the melt viscosity of PLA/WF composites also gradually increased.With the increase of fiber content and mesh number,the void defects at the cross section of the composite material will increase,so the water absorption rate of the PLA/WF composite material will increase accordingly.In summary,when the WF fiber content is 10%and the mesh number is 200 mesh,the comprehensive performance of the PLA/WF composite material is the best.(3)Study the effects of different levels of silane coupling agent KH550 on the compatibility,rheological properties and mechanical properties between PLA/PBAT blends and WF and PLA/PBAT matrix.Experiments show that when the amount of coupling agent is 3wt%,the tensile strength is increased by 136%.Coupling agent KH550 is covalently coupled with PLA and PBAT to form a graft polymer,and the compatibility of the two is improved.At the same time,the polycondensation reaction between the coupling agent and the hydroxyl group on the surface of WF effectively improved its compatibility with PLA/PBAT matrix,and the mechanical properties of PLA/PBAT/WF composite FDM parts were greatly improved.The viscosity of the composite material decreases with the increase of the content of the coupling agent.When the content is 3wt%,the comprehensive printing performance of the wire and the quality of the product are the best.