Research On Additive Manufacturing Of Thermotropic Liquid Crystal Polymer/Polyetherimide Composites

Fused deposition modeling additive manufacturing technology can realize the rapid manufacturing of complex-shaped products of polymer materials,and has become one of the most popular additive manufacturing technologies.The fabrication of hightstrength,corrosion-resistant and lightweight special engineering polymer parts satisfies the customized demands of modern manufacturing for lightweight and multifunctional products,and is gradually replacing metal and ceramic materials.Polyetherimide(PEI)has excellent materialproperties and good application prospects in high-end manufacturing industries such as defense and military,aerospace and automotive electronics,but its poor processability and difficulty in forming complex structures greatly limit the engineering applications of PEI.Therefore,it is crucial to develop high mechanical performance and multifunctional PEI composite 3D prnitng consumables and fused deposition modeling additive manufacturing crafts.The aim of this research is to achieve in-situ compounding of PEI with thermotropic liquid crystal polymer(TLCP),and to use TLCP as a carrier to carry multi-walled carbon nanotubes(MWCNTs)to build a double-percolation continuous structure in MWCNTs/TLCP/PEI composites.In this research,the influences of forming parameters on the mechanical performance are investigated.The polyetherimide ternary composites with high strength,multi-functionality,and excellent processing properties through in-situ composite of thermotropic liquid crystal polymers and polyetherimide with the introduction of multi-walled carbon nanotube conductive fillers are prepared and used for additive manufacturing research.In this paper,the influence laws of forming parameters on the mechanical properties of polyetherimide 3D printed samples are studied.The 3D printing filaments of PEI are prepared and the process parameters of filament extrusion are summarized.The effects of core process parameters of printing nozzle temperature,layer thickness and printing speed on the tensile and bending properties of PEI samples are studied.The mechanical properties of PEI samples are improved by optimizing the forming parameters to ameliorate the warpage and layer bonding quality of the samples.The selection of proper forming parameters can help improve the interlayer bonding state of the samples,and thus improve the mechanical properties of the samples.The in-situ composites performance study of thermotropic liquid crystal polymer and polyetherimide is carried out,and the enhancement mechanism of thermotropic liquid crystal polymer microfibers on the performance of polyetherimide matrix is analyzed.The process parameters for the preparation of TLCP/PEI in-situ composite filaments are clarified.The effects of the thermotropic liquid crystal polymer on the thermal properties,water absorption properties,tensile properties and surface wetting properties of the in-situ composites are investigated.The thermotropic liquid crystal polymers can increase the chain segment motion activity of the composites,raise the glass transition temperature,substantially enhance the tensile mechanical properties and improve the hydrophobicity of TLCP/PEI.Based on thermotropic liquid crystal polymer/polyetherimide in-situ composites,MWCNTs/TLCP/PEI ternary composite 3D printing filaments with different multiwalled carbon nanotube contents are prepared.The effects of multi-walled carbon nanotubes on the thermal properties of the composites are investigated.The mechanical properties and electrical conductivity of the ternary composites are tested and the formation of electrical conductivity pathways in the printed samples is verified.The surface roughness,contact angle and friction wear properties of the samples are tested to analyze the influences of multi-walled carbon nanotubes on the surface properties and friction wear properties of the composites.The multi-walled carbon nanotubes can increase the glass transition temperature of the composites,and MWCNTs/TLCP/PEI obtains better electrical conductivity at the cost of loss of mechanical properties,and the over-permeability threshold is about 2 wt%.The multi-walled carbon nanotubes can enhance the smoothness of the sample during the friction process and reduce the variation of the friction coefficient.In this paper,we research the additive manufacturing of polyetherimide and its composites.The influences of forming parameters on the mechanical properties of polyetherimide are explored.The in-situ composite of thermotropic liquid crystal polymer and polyetherimide is realized.The multi-walled carbon nanotubes are introduced to build a double percolation conductive structure.The additive manufacturing of MWCNTs/TLCP/PEI with high strength and multifunctionality is realized,which has a great prospect in mechanical manufacturing,electrical and electronic fields.