Study On Preparation And Properties Of Halogen-Free Flame Retardant And Toughening Polylactic Acid 3d Printing Composite

Polylactic acid(PLA),as a thermoplastic biodegradable aliphatic polyester material,has attracted much attention in recent years,because of its excellent biocompatibility,high transparency,high modulus and high strength.With the development of 3D printing technology,as a friendly environmental-friendly material,PLA has a broad application prospect in the field of 3D printing.However,as a 3D printing consumables requires material has good fluidity and toughness,which can prevent it from blocking the nozzle and broken wires in the printing process.It's low toughness,poor fluxility and flammability and other shortcomings limiting the application in the field of 3D printing.Firstly,this paper systematically reviewed study on flame retardant,the toughening modification and 3D printing.Secondly,in order to modify the brittleness and flame retardant properties of PLA,the composites were prepared using poly(lactic acid)(PLA using polyethylene glycol(PEG),poly(butylene succinate)(PBS),ethylene vinyl acetate(EVA),ammonium polyphosphate(APP)and liquid crystal polymer(LCP).The composites was evaluated by limiting oxygen index(LOI),UL-94 vertical burning,thermogravimetric analysis(TGA),differential scanning calorimetry(DSC),the tensile tests,scanning electron microscopy(SEM)and melt flow rate(MFR).The main research work is as follows:(1)The PLA/PEG/APP/LCP flame retardant and toughening composite were prepared by melt blending.Results showed that PLA composite with only 15wt% APP exhibited excellent flame retardancy performance(LOI=33% and UL-94 V-0 rating).The TGA showed the addition of LCP reduced the temperature of the maximum decomposition rate.The tensile strength of the composites was improved from 4.1% to 75.2% by adding 15% PEG,and the elongation at break of the composites increased with the increase of the LCP,when the 1.0%LCP was added,the elongation at break decreased from 57.1% to 19.38%.The SEM test of the fracture surface after tensile tests shows that PEG has better compatibility with PLA,which shows toughness fracture and phase separation of APP and PLA.It was found that the addition of LCP could improve the processing fluidity of the composites,and the MFR increased from7.01 g / 10 min to 14.09 g / 10 min.(2)The PLA/PBS/APP flame retardant and toughening system were prepared by melt blending.PLA composites with 20% APP showed a LOI value of 31.5 and V-0 rating in UL-94 tests.The TGA showed the initial decomposition temperature of the composites was increased by 10 ?,and the residual carbon increased from 0.2% to 16.8% with the increase of APP.The tensile test show that the impact strength and elongation at break of the composites increased significantly with the addition of PBS,and the tensile strength and elongation at break of the composites decrease with the increase of APP content.The SEM test of the fracture surface after tensile tests shows that PLA and PBS are not compatible fully,the APP and PLA has phase separation phenomenon.The MFR of the composites first increased and then decreased with the increase of APP,and reached the maximum value of 27.41g/10 min when the APP content was 15%.(3)The PLA/EVA/APP flame retardant and toughening system were prepared by melt blending.The LOI and vertical burning results showed that composite with 20wt% APP exhibited excellent flame retardancy(LOI=28.3% and UL-94 V-0 rating).The TGA showed the initial decomposition temperature of the composites was increased by 10 ?,and the residual carbon increased from 1.34% to 20.26% with the increase of APP.The tensile test show that the impact strength and elongation at break of the composites increased significantly with the addition of PBS,and the tensile strength and elongation at break of the composites decrease with the increase of APP content.The SEM test of the fracture surface after tensile tests shows that the compatibility of PLA and EVA is poor,the APP and PLA has phase separation phenomenon.The MFR of the composites first increased and then decreased with the increase of content of APP,and reached the maximum value of 22.51g/10 min when the APP content was 10%.