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

材料挤压是聚合物增材制造的一种形式，在这种制造中，长丝被一层一层地挤压到床上，可以制造出比传统制造方法更复杂的几何部件。分层构建部件，这使得几何自由度很大，但也限制了打印部件的机械完整性。打印层之间的粘合质量产生的零件的机械强度低于传统成型方法制造的零件。这个学术联络与工业（GOALI）研究项目的资助机会旨在了解聚合物特性和加工条件如何相互作用，以及如何操纵它们来增强材料挤压增材制造中的层间粘合。所获得的知识将用于为增材制造工艺定制聚合物性能，并用于打印具有适合功能应用的机械性能的组件。成功将大大提高美国增材制造基地的竞争力，为制造具有成本效益的功能性聚合物组件提供了一条途径。该奖项亦有助培训未来的工作人员；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的经验。由于这是一个与汉高公司的产学研合作项目，参与其中的学生也将了解工业挑战和驱动因素。计划中的聚合物增材制造研讨会将向在这一制造领域寻求新机会的行业传播知识。本研究将检验以下假设：层间扩散是挤压温度和玻璃化转变温度之差的函数，焊接强度取决于玻璃化转变温度和熔体温度之差以及温度相关的润湿。这就需要了解材料的热特性和增材制造工艺，以及它们如何影响打印结构的物理和机械性能。为了实现这一目标，将承担三大研究任务：1。确定了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影响；2. 了解结晶动力学对增材制造结构中形成的晶体形态的影响；3. 了解玻璃增强如何影响结晶，传热和机械性能。通过了解装配条件对产生的物理和机械性能的作用，这项工作将导致改进和定制对结构功能至关重要的物理和机械聚合物性能。这项研究还将为如何根据热学和物理性质制定用于增材制造的聚合物提供指导。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.