Study On 3D Printer And Process For Fully-biomass Composites

3D printing technology,also known as additive manufacturing,has been a hot spot in recent decades,which has been involved in many fields of application.Environmental protection,green manufacturing,the pursuit of sustainable economic development and the search for alternatives to nonrenewable resources have always been hot issues of global concern.Renewable biomass materials with a wide range of sources will become the most potential substitute for petroleum-based resources.The combination of fully-biomass composites and 3D printing can accurately design and manufacture biomass composites according to needs.Polyhydroxyalkanoate and wood flour(PHA/WF)melt blending and fused deposition 3D printing are combined to broaden the application of fully-biomass materials in the field of additive manufacturing,however,WF/PHA composites are used in filaments extrusion 3D printing have difficulties in filament preparation,discontinuous feeding,nozzle clogging and printed parts warping.Therefore,there is an urgent need to develop 3D printing equipment suitable for the characteristics of fully-biomass composites.The main research work is as follows:(1)In order to solve the problem that it is difficult to form the fully-biomass composites by fused deposition modeling technology,a micro-screw 3D printer for fully-biomass composites with different characteristics was invented.The micro-screw runs through the hopper and is forced to feed as the driver to achieve higher feeding efficiency;the heating module is designed and installed on the outside of the barrel with a melting cavity to improve the melt plasticization and printing efficiency of the composite;the matching of the micro-screw extruder and the conventional fused deposition modeling system is realized;(2)The thermal stress coupled numerical simulation of printing process was carried out by the method of birth and death element.Combined with the shape evolution of biomass composites in the process of micro-screw extrusion deposition printing,the mechanism of the blending composite on the longitudinal and horizontal anisotropy and warping deformation improvement of 3D printing products was explored by melt homogenization and pressure construction of micro-screw;(3)Based on the analysis and study on mechanical,thermal and microstructure of the 3D printing product,this paper puts forward a method to control the performance of 3D printing products by adjusting the printing process parameters by extrusion flow rate,which provides guidance for 3D printing of fully-biomass composites.The relationship of the structural parameters of micro-screw extrusion 3D printer,material characteristic parameters and product performance was further clarified.Based on the above,the enhancement methods of 3D printing products of fully-biomass composites were studied.The modification of the composites by dopamine modified wood flour and the microfibrillated cellulose with a larger aspect ratio was studied,respectively.The optimum device and process parameters were adapted to realize the high-performance material manufacturing of the fully-biomass composites.