Research On Additive Manufacturing Mechanism Of Polyetheretherketone And Its Composites

Polyetheretherketone(PEEK)is a semi-crystalline thermoplastics polymer with high performance.With the development of science and technology,the application in mechanical manufacturing,biomedical,aerospace and other fields of special engineering plastics such as PEEK materials are limited by processing method.Additive manufacturing(AM)technology is an important means to accelerate the realization of intelligent manufacturing.Promising approaches to produce complex shapes,integrated processing of multi-scale structures and manufacturing without assembly final part are produced layer by layer.In this study,additive manufacturing of PEEK and its composites with high forming accuracy,controllable mechanical strength and high bioactivity has been carried out as follow: the development of additive manufacturing system,the preparation of PEEK and its composites,the exploration of printing parameters and the surface modification of HA/PEEK scaffold.These research are play an important role to promote the application of PEEK materials in various fields.The work can be divided into the following four parts:1.Designation and development of PEEK additive manufacturing system.The system mainly consists of motion system,temperature control system and extrusion system.The motion system realizes the movement of extrusion nozzle in three-dimensional space.The temperature control system controls the temperature of nozzle,building platform and other parts,keep the system at constant temperature,which reducing the thermal stress.And the extrusion system provides the feedstock material and extrude filament in printing process.The PEEK additive manufacturing system realizes the collaborative work through the software developed in LabVIEW environment.PEEK and its composites can be printed in any complex parts by the PEEK additive manufacturing system.2.The relationship between extrusion speed,printing speed,extrusion multiplier and the accuracy and strength of extruded filaments was studied under the process of extrusion PEEK materials.The maximum extrusion force,minimum extrusion force and melt chamber pressure were measured,and their effects on the surface morphology and the dimension of extruded filament were analyzed.Based on the analysis of the melt extrusion process of PEEK materials,the relationship between extrusion speed and the diameter of extruded filament was established.By means of adjusting printing speed and extrusion multiplier,the dimension of printing line and the distribution of filament in PEEK samples can be controlled.Choosing appropriate printing parameters is the main method to enhance the accuracy of PEEK additive manufacturing samples.3.The mechanical properties of the PEEK printing samples were affected by the mass of the melt extrusion filament and the printing pattern in the inner layer.The effects of the melt extrusion and filament alignment parameters on the tensile strength,impact strength,and fracture toughness of additive manufacturing PEEK samples under different printing directions were analyzed by definitive screening design method.Based on the analysis of fracture morphology of PEEK samples,the mechanism of the effect of different printing parameters on the mechanical properties of PEEK 3D printing samples was explored.The effect of printing parameters on the properties of PEEK samples is complex,this study provides a useful guide for the selection of appropriate printing parameters to realize a diverse range of mechanical properties for additive manufacturing PEEK samples.4.By modifying the surface of hydroxyapatite,10 wt.%-40 wt.% hydroxyapatite/PEEK additive manufacturing composites material was prepared.The effects of HA content,infill density,infill pattern and strain rate on the energy loss and maximum compression strength of the HA/PEEK scaffold in the cyclic compression process were analyzed.By sulfonating the HA/PEEK surface and modifying the HA surface,HA nucleation sites were introduced on the surface of the HA/PEEK scaffold to enhance the surface activity of the HA/PEEK scaffold.The additive manufacturing equipment,material,printing parameters and surface treatment method of PEEK and its composites were studied,realizing the high precision dimension,controllable mechanical strength,high biological activity of PEEK and its composites printing.The technology shows huge potential in the medical field,which laid the foundation for realizing additive manufacturing technology of high-performance PEEK materials.