Preparation Of Modified PETG 3D Printing Filament And Its FDM Process Optimization

In this dissertation,polyethylene terephthalate-1.4 cyclohexane-dimethylol ester(PETG)was used as the research basic material.The enhancement and toughening modification was studied by using the melt blending principle to prepare 3D filament of PETG with high performance and low cost.The orthogonal test was used to screen FDM molding process and determine the optimal process parameters.First,PETG was enhanced by blending with the polycarbonate(PC)to prepare the PETG/PC 3D printing filament.The mechanical properties,microstructures,rheological properties and forming properties of the materials were studied by universal mechanical testing machine,SEM,FI-IR,TG,rotational rheometer and DSC respectively.The results show that the FDM tensile strength and flexural strength of PETG/PC systems were gradually increased with increasing of PC content.And when PETG/PC=80/20,the tensile strength of the system is 7.41 MPa which is higher than that of pure PETQ and this system has a better molding.SEM's results show that the compatibility of the PETG/PC systems were increased first and then decreased with increasing of PC content.The PETG/PC=80/20 system has better compatibility.The transesterification inhibitor(NaH2POa)makes the phase morphology of the system clearer,indicating that the compatibility of PETG/PC is worse.The rheological properties show that the storage modulus(G'),the loss modulus(G")and complex viscosity(?*)were increased with increasing of PC content.The system changes from liquid to solid with increasing of the angular frequency.The Cole-cole plot shows that the compatibility of the PETG/PC system is poor,and the relaxation spectrum shows that the interface relaxation also moves to a zone of longtime.Above these indicate that the entanglement of molecular chain is increased and the movement becomes difficult.Second,PETG/PC was toughened with MBS to prepare the PETG/PC/MBS 3D printing filament.The notched impact strength of PETG/PC/MBS can be increased with the introduction of MBS.For example,the notched impact strength was increased significantly from 1.75 kJ/m2(PPM-10)to 17.55 kJ/m2(PP-82)but the tensile strength and flexural strength were decreased.SEM's results show that MBS not only can be used as flexibilizer of PETG/PC,but also can be used as compatibilizer.The rheological properties showed that with increasing of MBS content,G' and G" of blends were rose,and ?*was rose in the low-frequency area,but falled in high-frequency area.In addition,Cole-cole and DMA figures indicate that compatibility of blends was increased.Compared with FDM products,it was found that the molding performance of PETG/PC/MBS filement was better and the molding temperature was lower.Finally,for PPM-10 system,a three-factor,three-level(L9(33))and a four-factor,four-level(L16(44))were set up for an orthonormal experiment.The notched impact strength,the suspended structure deformation(h)and the surface roughness(Ra)of the FDM under different technological parameters were studied by range and variance analysis.The experimental results show that in(L16(44)),the thickness of the printing layer has the most significant impact on the notched impact strength,with a significant value of 0.037(<0.05,that is,95%is related to the thickness of the layer).The best process parameter is A1B2C4D1from the variance analysis,and the notched impact strength is 13.9 kJ/m2.In(L9(33)),the printing temperature and the printing layer thickness has significant effects on h and Ra,respectively.The significant values are 0.015 and 0.004,respectively.The variance analysis showed that the best process parameters were A1B3C3 and A3B3C1 respectively.And h=2.01 mm,Ra=10.6 ?m were obtained.