Preparation And Properties Of Modified Polylactic Acid Filaments For 3D Printing

Fused deposition molding(FDM)is a three-dimensional printing technology of extrusion molding for using thermoplastic monofilament through a hot nozzle,which has the advantages of the low cost,high reliability and simple operation.However,the printable filaments’material has been the main factor restricting the development of FDM technology.At present,polylactic acid(PLA)filaments are the most used FDM3D printing biodegradable material.However,the purely PLA has the problem of large brittleness and high shrinkage factor of its 3D printing products.As a result,PLA can not satisfied the requirements of practical application.Therefore,we prepared modified PLA filaments through PCL blending PLA.At the same time,acetyl tributyl citrate(ATBC)was used as two-phase compatibilizer to solve the compatibility problem between PLA and PCL.The impact of PCL and ATBC’s contentthe extrusion process of the preparation,the performance of filaments,and the impact of the printing process on the performance of printing product were emphatically studied.The detailed contents are as follow:(1)The filaments of PLA were prepared by desktop extruder.The effect of extruding temperature and screw speed on the filaments’diameter,density and ultimate tensile stress were systematically investigated.The printing performance of qualified PLA filaments was tested by FDM 3D printer.The influence of printing thickness,printing temperature and printing speed on the printing parts were systematically studied.It was found that qualified filaments could be obtained under conditions of extrusion temperature 190-195℃and screw speed 2-5 rpm.When build layer is 0.1mm,extruder temperature is 220℃and speed while extruding is 60mm/s,best printing effect with a relative dimensional error of 0.011±0.005,surface roughness of 5.2±0.6μm,density of 1.16±0.07 g/cm~3 and tensile strength of 51.7±1.1 MPa could be achieved.The printing parameters of the PLA filaments are the reference for the printed product parameters of the blends’filaments at the next step.(2)A novel biodegradable PLA/PCL blends’filaments of the 3D printing were prepared by using polylactic acid(PLA)and polycaprolactone(PCL)as raw materials.The blended filaments and samples were prepared by the desktop extruder and the FDM3D printer respectively.This article systematically investigated the effect of the PCL content on the diameter,density,surface roughness and ultimate tensile stress of the obtained bends’s filaments,and researched effects of PCL content on the morphology,water absorption,hydrophilicity,rheology and mechanical properties of the bends.The results indicated the diameter,density,ultimate tensile stress water absorption gradually reduce with the increase of PCL content,while the surface roughness and water contact angle gradually increase with the increase of PCL content.The complex viscosities,dynamic storage modulus and loss modulus of PLA/PCL bends show the trend of increase first and then decrease with the increase of PCL content,when the mass fraction of PCL is 30 wt%,the complex viscosity,dynamic storage modulus and loss modulus of the blend is reached maximum,in addition,the complex viscosities,dynamic storage modulus and loss modulus of pure PLA bigger than bigger the blends,and when the content of PCL is 40%,the elongation at break and the impact strength of the blended samples were raised by 478%and 197%respectively.(3)A novel biodegradable PLA/PCL/ATBC blends’filaments of the 3D printing were prepared by using tributyl acetyl citrate(ATBC)as the compatibilizer,and were prepared by the desktop extruder and the FDM 3D printer respectively.The effects of ATBC content on the filaments’diameter,surface roughness,ultimate tensile stress,compatibility,together with the water absorption and mechanical properties of the 3D printed parts,were systematically studied.The results show that the diameter,surface roughness and the tensile strength of the filaments of PLA/PCL blends gradually decreases with the increase of ATBC content,and the compatibility of the filaments was improved.The water absorption and tensile strength is reduced,but the impact performance is effectively improved with the addition of ATBC.The breaking elongation of the printed parts can reach 94.6%,and the impact strength reaches10.5KJ/m~2 when the amount of ATBC relative to PLA/PCL blends is 6%,the impact strength of the blended samples were raised by 61.5%.