半结晶聚合物控形控性微球化工艺及熔限拓宽机理研究

Semi-crystalline polymers with high sphericity, high spheroidization rate and specific crystal structure/crystallinity are promising raw materials for selective laser sintering (SLS) technology and vastly demanded in many application areas. However, such semi-crystalline polymers are difficult to produce with traditional preparation methods, which inhibit the application of SLS technology. Previous studies show that the major techniques to increase molding temperature window include widening the melting range, lowering the melting temperature, which also associated with crystallization temperature. In this project, we propose an ‘isostatic pressing’ technology to investigate the following issues about the semi-crystalline polymers: 1) Exploring the “isostatic pressing” process and its main technical parameters; 2) Clarifying the regular pattern during producing the spherical macro particles with specific crystal structure/crystallinity; 3) Confirming the relationship between the melting range and crystal structure/crystallinity. This project will provide new insight into the inner mechanisms for the interactions between the spherical macro particles and the laser, which offer new theoretical frameworks to understand the controllable production of the semi-crystalline spherical micro particles, and provide references for manufacturing complicate structures with the SLS technology.

高球形度、球化率、特定晶型和结晶度的半结晶聚合物粉体，是选择性激光烧结（SLS）制造出理化性能优异成形件的先决条件之一。但现有半结晶聚合物粉体制备工艺难以满足上述要求，成为制约SLS技术优势发挥的关键问题。针对上述问题与需求，本项目提出“仿温等静压法”制备该聚合物微球化粉体的工艺，探索相关问题解决途径。研究内容包括：（1）“仿温等静压法”粉体微球化控形控性制备工艺；（2）研究半结晶聚合物微球化粉体的熔限拓宽机理；（3）开展上述微球化粉体的SLS成形实验与性能表征。通过以上研究，确立半结晶聚合物粉体微球化的关键技术和工艺体系，揭示微球化粉体的晶型、结晶度等特性参数演变规律，及微球化过程中的控形控性工艺机理，阐明粉体晶型、结晶度与熔限拓宽的内在联系。本项目的实施，将深化对半结晶聚合物粉体微球化可控性制备及其SLS成形机理的认识，对促进该技术在聚合物复杂结构件成形制备方面的应用有重要意义。

本项目围绕选择性激光烧结（SLS）增材制造技术急需的半结晶聚合物微球化粉体开展研究。以不规则聚丙烯（PP）粉体为基础原料，发展了“高温诱导结晶微球化法”和“相反转乳化微球化法”，实现了PP粉体的高球形度、高球化率、特定晶型、特定结晶度的控形控性制备，研究了微球化PP粉体的“烧结窗口拓宽”机理，及与其SLS成形件的翘曲变形、成形尺寸精度的内在关联性。.主要研究内容与成果如下：.（1）研究PP粉体微球化的温度、分散介质、球化时间、剪切速率等工艺参数对粉体结晶特性（结晶度、晶型等）和形貌的调控规律，发展了PP粉体的控形控性微球化制备技术；.（2）研究PP粉体的熔融温度范围、晶型、结晶度的演变规律，阐明SLS“烧结窗口拓宽”机理；.（3）明晰了PP粉末的烧结窗口、结晶度与SLS成形件翘曲变形的内在关联。.本项目的研究成果，为半结晶聚合物粉体的控形控性微球化制备，及其SLS成形件的激光烧结提供理论依据与技术支撑，对促进聚合物SLS成形技术的应用具有重要意义。