Fused deposition modeling(FDM)is a widely used rapid prototyping process,but the produced thermoplastic prototypes have poor mechanical properties.By combining gas-assisted extrusion with FDM technology,high-temperature and high-pressure gas is used to instantly heat and pressurize the extruded filament and the deposited surface,thereby improving the mechanical strength of the parts.A 3D printing material of polylactic acid(PLA)modified by blending thermoplastic polyurethane(TPU)and glass fiber(GF)was prepared,the rheological properties of PLA before and af-ter modification were compared.The influences of different gas auxiliary parameters,such as gas temperature,gas flow and gas pressure on tensile properties and impact strength were studied.The results show that PLA modified with GF and TPU has stronger non-Newtonian properties than pure PLA,and its rheological properties have been improved,which is beneficial for 3D printing.The interlayer strength of the printed parts formed by gas-assisted FDM 3D printing is higher than that without gas assistance,and the interlayer strength can be increased by 116.1％.Different gas parameters have different effects on mechanical properties of FDM printed parts,and the effect of gas flow rate is more remarkable than others.While,the gas temperature,flow rate and pressure are set at 250℃,0.8 L/min and 0.4 MPa respectively,the printed parts have best performance.
维普
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