GOALI: Experimental and Computational Approaches to Tailor Properties of Additively Manufactured Semi-Crystalline Polymers

材料挤出是一种聚合物添加剂制造形式，将细丝逐层挤出到床上，可以制造出远远超过传统制造方法的几何复杂性的部件。分层构建零件可以实现很大的几何自由度，但也限制了打印零件的机械完整性。印刷层之间的粘合质量产生的零件机械强度低于传统成型方法制造的零件。GOALI(GOALI)研究项目旨在了解聚合物性能和加工条件是如何相互作用的，以及如何在材料挤压添加剂制造中利用它们来增强层间结合。所获得的知识将被用于为添加剂制造过程量身定做聚合物特性，以及打印具有适合功能应用的机械特性的部件。该产品的成功将极大地提高美国添加剂制造基地的竞争力，为生产具有成本效益的功能性聚合物部件提供了一条途径。该奖项还将促进未来劳动力的培训；研究生和本科生都将参与研究活动，并将获得先进制造和聚合物科学方面的经验。由于这是一个与汉高集团合作的产学研合作项目，参与的学生还将了解行业挑战和驱动因素。计划中的聚合物添加剂制造研讨会将向在该制造领域寻找新机会的行业传播知识。这项研究将检验以下假设：层间扩散是挤出温度和玻璃化转变温度之间的差的函数，焊接强度取决于玻璃化转变温度和熔体温度之间的差异以及与温度有关的润湿。这需要了解材料的热特性和添加剂制造工艺，以及它们如何影响印刷结构的物理和机械性能。为了实现这一目标，将开展三项主要研究工作：1.确定玻璃化转变温度和熔体温度之间的差异对印刷半结晶聚合物的焊接强度和残余应力的作用；2.了解结晶动力学对附加制造结构中形成的结晶形态的影响；3.了解玻璃增强如何影响结晶、热传递和机械性能。通过了解组装条件对所产生的物理和机械性能的影响，这项工作将导致对结构功能至关重要的改进和可定制的物理和机械聚合物性能。这项研究还将为如何根据热和物理特性配制用于添加剂制造的聚合物提供指导。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Material extrusion, a form of polymer additive manufacturing in which a filament is extruded layer-by-layer onto a bed, can manufacture components with geometric complexity far beyond that possible with conventional manufacturing methods. Building the part in layers, which enables great geometric freedom, also limits the mechanical integrity of the printed part. The bonding quality between printed layers yields parts with lower mechanical strength than if they were manufactured by traditional molding methods. This Grant Opportunity for Academic Liaison with Industry (GOALI) research project seeks to understand how polymer properties and processing conditions interact, and how they can both be manipulated to enhance interlayer bonding in material extrusion additive manufacturing. The knowledge gained will be leveraged to both tailor polymer properties for additive manufacturing processes, and to print components with mechanical properties appropriate for functional applications. Success will greatly enhance the competitiveness of the US additive manufacturing base by providing a pathway towards the manufacture of cost effective, functional polymeric components. This award will also facilitate training of the future workforce; both graduate and undergraduate students will be involved in the research activities and will gain experience in advanced manufacturing and polymer science. As this is an industry-university collaborative project with Henkel Corporation, the students involved will also gain an understanding of industrial challenges and drivers. Planned workshops on polymer additive manufacturing will disseminate the knowledge to industries seeking new opportunities in this manufacturing arena.This research will test the hypotheses that interlayer diffusion is a function of the difference between extrusion temperature and glass transition temperature, and that weld strength is dependent on the difference between the glass transition temperature and melt temperature as well as temperature-dependent wetting. This necessitates an understanding of the thermal characteristics of the material and the additive manufacturing process, and how they affect physical and mechanical properties of a printed structure. Towards this goal, three major research tasks will be undertaken: 1. Determine the role of the difference between the glass transition and melt temperatures in weld strength and residual stress of printed semi-crystalline polymers; 2. Understand the impact of crystallization kinetics on the crystalline morphology formed in additively manufactured structures; 3. Understand how glass reinforcement affects crystallization, heat transfer, and mechanical properties. By understanding the role of assembly conditions on resulting physical and mechanical properties, the work will lead to improved and tailorable physical and mechanical polymer properties essential to structure functionality. This research will also provide guidance in how to formulate polymers for additive manufacturing, based on thermal and physical properties.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.