Abstract: The effects of thermoplastic polyurethane(TPU)powder on the performance of gypsum-based 3D printing specimens and the printing process were studied. The results show that the compressive and tensile strength as well as water resistance of the 3D printing specimens increases with the content of TPU powder,but when there is too many TPU powders,the dimension error would become greater and the printed specimens would be damaged more easily and show wrong layer during 3D printing. Through synthetical considerations of the surface features,dimensional accuracy,water resistance and mechanical properties of the printed specimens and the smoothness of the printing process,the optimal mass ratio of TPU powder and gypsum powder is in the range of 40:50 to 50:40. The minimum dimensional deviation of the printing specimen was achieved when the content of TPU powder is 50%(in mass),and the compressive strength and tensile strength are increased by 38.5% and 117.4% respectively,compared with the pure gypsum-based 3D printing specimens. The formation of ribbon plastic structure inside the 3D printing specimens after thermal post-processing is responsible for the improvements of compressive and tensile strength,density and water resistance.

Key words: polymer processing, powders, composites, TPU/gypsum composited powder, three dimensional printing

摘要： 研究了热塑性聚氨酯（TPU）粉末对石膏基三维打印的成型过程和3D打印成品性能的影响规律，研究结果表明随着TPU粉末含量的增加，打印成品的机械强度和耐水性能变好；但TPU粉末含量过高时，打印成品的尺寸偏差较大，易破损且打印时出现错层。综合考虑打印成品的表面特征、尺寸精度、耐水性、机械强度以及打印过程的流畅性，TPU粉末和石膏粉末较佳的质量配比为（40∶50）～（50∶40）。当TPU粉末质量分数为50%时，打印成品的尺寸偏差最小，此时其抗压强度和拉伸强度比纯石膏3D打印成品分别提高了38.5%和117.4%。打印成品内部热塑性聚氨酯粉末经热熔融/常温冷却固化后处理形成的带状塑性结构是改善打印成品抗压和拉伸强度以及增加其致密性和耐水性的主要原因。

关键词: 聚合物加工, 粉体, 复合材料, 聚氨酯/硫酸钙复合粉末, 三维打印