Preparation And Pilot Production Of PLA-based 3D Printing Wire

It is clear that biodegradable polymer Poly(lactic acid)(PLA)and Acrylonitrile Butadiene Styrene terpolymer(ABS)are the chief two materials employed as 3D printing-supplies for the Fused Deposition Molding technology(FDM).Compared to ABS,PLA is a fully biodegradable wire with better molding property and lower printing temperature and produces lower odors in the printing process.Unfortunately,the poor surface quality and low mechanical properties of the PLA 3D printing wire seriously hinder the further application of PLA on 3D printing technology.It is necessary to develop a modified PLA 3D printing wire with higher toughness for FDM 3D printing industry in the domestic.In this paper,a blending system with 20 wt%Poly(butylene succinate)(PBS)and 80 wt%PLA was prepared employing BPM520 as an impact modifier.BPM520 possesses a"shell-core" structure and can give PBS an association toughening effect with PBS.The influence of BPM520 dosage on the mechanical properties,crystallization properties,rheological properties and the phase morphology of the PLA/PBS(80/20)system was studied.It is clear that PLA/PBS(80/20)system with 7 phr BPM520 gives the optimal performance.Accordingly,FDM 3D printing wire was prepared using 7 phr BPM520 toughened PLA/PBS(80/20)system as a raw material.The 3D printing spline and the traditional injection molding spline were both prepared for investigating the mechanical properties of the prepared PLA 3D printing wire with a comparison to those of commercial one.The main experimental and results are given as follows.Firstly,by means of melt blending technology,PLA was toughening modified with PBS and BPM520.The using rotational rheometer,differential scanning calorimetry(DSC),scanning electron microscopy(SEM)and dynamic thermal mechanical analyzer(DMA)were used to study the influence of BPM520 dosage on the systematically rheological behavior,crystallization property,phase morphology as well as the mechanical properties of the PLA/PBS/BPM520 system.DSC analysis shows that,increasing the dosage of BPM520 causes to the increment of PLA,PBS and BPM520 molecular chain entanglement degree and decreasing the movement of the molecular chains,and finally leads to the imperfect of crystallization of blends.The results of rheological behavior,SEM and DMA analyses indicate that the compatibility of between PLA and PBS is poor,the presence of BPM520 not only toughens PLA/PBS system,but also improves the compatibility in PLA and PBS.The PLA/PBS(80/20)system toughened with 7 phr gives the highest notch impact strength of 16.27 kJ/m2,which is four times that of pure PLA,indicating that the best compatibility occurs among PLA,PBS and BPM520 in the system at the experimental conditions.Secondly,PLA/PBS/BPM520(80/20/7)system was selected to prepare the PLA 3D printing wire via melt blending-extruding method.The influence of printing conditions such as printer nozzle temperature,printing speed and printing plate temperature on the printing performance(printing fluency)and thermal-stability(yellowing)of the blend were investigated.The printing parameters were optimized for the prepared PLA/PBS/BPM520(80/20/7)system DSC,rotational rheometer and SEM were employed to study the difference of resultant PLA and commercial PLA between the traditional injection molding process and FDM 3D printing molding process.The results indicate that,the sample prepared by FDM 3D printing process gives better mechanical properties than that by injection molding.The sample obtained at the conditions of printing temperature of 210℃ and plate temperature of 95℃,possesses a tensile strength of 45.3 Mpa and a Flexural strength of 63.1 Mpa.The spline obtained at the printing temperature of 210℃ and the plate temperature of 85℃,gives a notched impact strength of 17.3 kJ/m2,which is higher than 16.27 kJ/m2 for the injection spline,The results of SEM analysis,DSC analysis and rheological behavior indicate that some part of PLA molecules orientate and crystallize during the printing process.As a result,the mechanical properties of the spline increase.Finally,owing to the high price and difficult to purchase of BPM520,a cheaper compound with "shell-core" structure,methyl methacrylate-butadiene-styrene copolymer(MBS)was employed to replace BPM520.The printing parameters for PLA/PBS/MBS 3D printing wire were also optimized.It is clear that the quality of this modified PLA materials meet the demand as a commercial PLA wire and the pilot production of the wire could be achieved.