Preparation And Research On ABS Nanocomposite Specimens Fabricated By Fused Deposition Modeling Technology

With the progress of technology and individual needs,three-dimensional printing(3DP)has been widely used in many fields,including aerospace,medical,electronic,architectural,food,and automobile applications.3DP is divided into many categories,while fused deposition modeling(FDM)is one of the mostimportanttechnologies because of its low cost,easy operation,and short processing cycle.Even though,FDM still cannot completely meet practical demand because of the limited mechanical properties of its products compared with injection and compression molding because of the characteristics of layer upon layer forming.With good dimensional stability,rigidity,and thermostability,nanofillers at a very low weight can improve the integrated performance of polymers and have little effect on the melt fluidity.This subject chooses ABS as the matrix and different nanofillers are used to modify the resin.The mechanical strength,mechanical anisotropy,and thermal performances of different ABS-based nanocomposite specimens fabricated by FDM were evaluated systematically.Firstly,structure and performance of ABS samples fabricated by FDM,injection,and compressionmolding were investigated.Results show that sample made by FDM has the lowest mechanical properties and density,and the tensile strength is just up to 70% of the value obtained from the injection-molded specimens.Printing speed,layer thickness,grating angle,and building orientation were optimized by orthogonal experiment.Mechanical tests show that when the thickness was 0.1 mm,sample printed in horizontal has the best mechanical performance,while vertical-direction-built parts generally have the worst tensile strength and impact resistance.The mechanical anisotropy of the pure ABS samples was very evident when the building orientation was changed.Then ABS nanocomposite filaments with inorganic nanofillers(SiO2,MMT,MWCNTs,and CaCO3)for FDM were prepared by melting extrusion and printed via a commercial 3D printer.It turns out that the addition of nanofillers significantly reduced the mechanical anisotropy and improved the mechanical strength and thermostability of the ABS samples fabricated by FDM technology.The disparity between the mechanical strength of FDM and injection-molded specimens is also narrowed.With the introduction of MMT,the tensile and flexural strength of ABS samples increased by 25.7% and 17.1%,respectively.The addition of CaCO3 lowered the mechanical anisotropy of ABS from 42.1% to 23.9%.Asakind of environmentalfriendly biomacromolecular material,nanocrystalline cellulose(CNC)has relatively high aspect ratio,strength and modulus,which make it a new type of green reinforcing filler for polymer materials.CNC extracted from microcrystalline cellulose in acid solution conditions has typical type I structure in this paper.The length of CNC is about 300 nm,diameter is about 10 nm,and the crystallinity is up to 71.2%.Thermogravimetric analysis shows that CNC has poor thermal stability,which results it difficult to be used in melting process of thermoplastic polymer.To improve the thermal stability of CNC,the thesis used ethyl orthosilicate(TEOS)as silica source precursor to prepare new nanocellulose composite particle(Hybrid)by sol-gel method.Energy Dispersive Spectrometer(EDS)exhibits the percentage of Si atom in Hybrid is 2.99%.Thermal analysis shows that the initial decomposition temperature and the temperature of maximum weightlessness of Hybirid are respectively increased by 52? and 22? than CNC.Then the effect of mechanical properties on ABS filled with Hybrid,CNC,SiO2,and MCS(SiO2 powder blend with CNC directly)are investigated and the results show that the Hybrid has the best reinforcing effects than other fillers.Moreover,several interfacial modifier were used to increase the compatibility between Hybrid and ABS matrix.The results demonstrate that silane coupling agent KH570 and ABS-MAH have better effect on ABS/Hybrid composite and the increase of impact strength of composites is 43% and 26%,correspondingly.When the filling portion of organic Hybrid is 3wt%,the composite has the best tensile and flexural strength,respectively improved 7.1MPa and 6.5MPa compared to pure ABS samples manufactured by FDM.At the same time,introduction of Hybrid improves the vicat softening temperature,adhesive strength between layers,shrinking percentage,and warp degree of ABS specimens.