用于选择性激光烧结技术的尼龙6/SiO2纳米复合微球制备与性能研究

At present, nylon 12 based powders are almost the only polymer material used for selective laser sintering (SLS) technology. The high cost and less variety of raw materials has greatly restricted the application of SLS technology. In order to make the material cheaper and more diverse, nylon 6 is the most preferable material. However, because of the poor technique for high quality microsphere preparation and the high water absorption, which will lead to a low thermal stability and dimensional stability during sintering process, the application of nylon 6 in SLS technology has not been success. In this project, a new kind of nylon 6/SiO2 composites microsphere structure is designed and constructed by in situ generating nano SiO2 in a nylon 6 porous microsphere framework, thus achieve well dispersion of large number of nano SiO2 in nylon 6 matrix. The in-situ preparation technology and the effect of the structure on properties are investigated to get controllable preparation of the composites microsphere. Water absorption, thermal stability, crystallization and the mechanical strength of the nylon 6 composites microsphere are improved through introduction of hydrophobic SiO2 and improve crystallinity and surface rough degree of nylon 6 matrix. The smooth implementation of the project will provide a new way for preparation of functional polymer composites, and lay a foundation for the research and development of low cost, high performance powder materials for use in in SLS technique.

目前选择性激光烧结（SLS）技术几乎都以尼龙12基粉末为耗材，原料成本高、种类少极大限制了SLS技术的应用。尼龙6是SLS技术耗材廉价化、多样化的首选材料。本项目针对目前SLS用高性能尼龙6微球制备技术不成熟、材料吸水率高，易导致烧结过程热稳定性和尺寸稳定性差的缺点，设计一种新型SLS用尼龙6/SiO2复合微球结构。创造性地在尼龙6多孔微球中原位生长纳米SiO2，实现大量纳米SiO2在尼龙6基体内部和表面高度分散。重点研究复合体系主客体原位生长技术及结构对性能的影响和控制规律，实现SLS用尼龙6复合微球的可控制备。通过疏水性SiO2引入、尼龙6基体结晶度及表面粗糙度的提高，协同解决尼龙6材料吸水率问题，同时有效提高尼龙6复合粉体的热稳定性、结晶性能及力学强度。项目的顺利实施能为功能化高分子复合材料制备提供新的方案，同时为低成本、高性能SLS技术用高分子粉末新材料制备奠定基础。

本项目通过调研目前几种主流3D打印技术及其所用材料，提出作为最具工业应用前景的选择性激光烧结技术（SLS）用材料其技术不成熟、材料单一、成本高、吸水率高、热稳定性和尺寸稳定性差的问题。针对性的以廉价的工程塑料尼龙6为原料，首先合成具有较大孔隙率和比表面积的尼龙6多孔微球，并优选20-80微米粒径的多孔尼龙6球为模板，采用原位聚合法，在尼龙6多孔微球中原位生长纳米SiO2，实现大量纳米SiO2在尼龙6基体内部和表面高度分散，得到了一种新型SLS用尼龙6/SiO2复合微球结构。分析了溶剂比例，PVP含量等实验参数对于微球尺寸和形貌的影响，通过研究纳米SiO2与尼龙6多分子间作用力及其对于复合微球形成的作用机理，以及不同水解过程对复合微球中纳米SiO2分散性、水解产率、复合材料表面微结构的影响，总结了复合体系主客体原位生长技术及结构对性能的影响和控制规律，实现SLS用尼龙6复合微球的可控制备。研究发现通过疏水性SiO2引入、尼龙6基体结晶度及表面粗糙度的提高，能够协同解决尼龙6材料吸水率问题，同时有效提高尼龙6复合粉体的热稳定性、结晶性能及力学强度。项目的顺利实施为低成本、高性能SLS技术用高分子粉末新材料制备提供了依据。