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采用固相剪切碾磨(S3M)技术并结合冷冻粉碎制备了适于选择性激光烧结(SLS)的尼龙12(PA12)/多壁碳纳米管(CNTs)复合粉体及相应的烧结制品.采用激光粒度分析仪、扫描电镜、透射电镜、动态力学分析、傅里叶变换红外光谱分析、差示扫描量热仪等对所得PA12/CNTs复合粉体和相应SLS制品的结构与性能进行了表征.结果表明,固相剪切碾磨-冷冻粉碎制备的复合粉体颗粒以椭球形为主,平均粒径75 μm,SLS加工窗口为10℃左右,满足SLS对被烧结材料的性能要求,通过加入质量分数为0.1％的流动助剂纳米SiO2能进一步改善复合粉体的SLS加工性能.磨盘碾磨通过其强大的三维剪切力场实现了CNTs的切割及在PA12基体中的良好分散以及CNTs与PA12大分子链的接枝,显著改善了二者之间的界面相容性.此外,通过优化SLS加工参数,成功制备了表面平整、结构复杂、性能良好的PA12/CNTs烧结制品.所得PA12/CNTs烧结样品具有优良的力学性能,拉伸强度达到44.2MPa,缺口冲击强度达到8.12 M/m2.

Solid state shear milling (S3M) technology in combination with cryogenic pulverization was used to prepare the co-powders of nylon 12 (PA12) with carbon nanotubes (CNTs) suitable for the selective laser sintering (SIS) and the corresponding sintered products.The laser scattering particle analyzer,scanning electronic microscope (SEM),transmission electronic microscope (TEM),dynamic mechanical analyzer (DMA),Fourier transform infrared spectrometer (FT-IR) and differential scanning calorimeter (DSC) were used to characterize the structure and performance of the obtained PA12/CNTs co-powders and the corresponding SLS samples.The results show that the PA12/CNTs co-powders prepared through S3M technology and cryogenic pulverization mostly have the ellipsoid shape,average particle size of 75μm and SLS processing window of about 10 C,which satisfies the requirements of SLS process for the performance of the sintered material.The addition of 0.1％ flow additive nano silica further improves the SLS processability of the prepared co-powders.Pan-milling realizes the cutting of CNTs,the better dispersion of CNTs in PA12 matrix and the grafting of CNTs onto PA12 macromolecular chains under its very strong three dimensional shear force field,remarkably enhancing the interfacial compatibility between both phases.In addition,the.PA12/CNTs sintered products with smooth surface,complex structure and good property were successfully fabricated through optimizing the SLS processing parameters.The obtained PA12/CNTs SLS samples show the good mechanical performance,achieving tensile strength of 44.2 MPa and notched impact strength of 8.12 kJ/m2.