Collaborative Research: High-Strain-Rate Dynamics of Copolymer Microparticles for Advanced Additive Manufacturing

在冷颗粒气体喷涂制造技术中，亚或超音速喷涂原料粉末或微尺寸聚合物颗粒可以实现独特的添加剂加工，而无需使用挥发性有机化合物，因为微粒在与基材碰撞过程中会发生极端变形。当固结发生在微粒的熔化温度以下时，由碰撞引起的变形产生的非凡纳米结构可以保留下来，并有助于最终产品的性能。因此，可以设想具有纳米级沉积材料工程能力的先进增材制造。多相共聚物在冷粒子气体喷涂工艺中表现出良好的固有材料性能，是一种很有前途的材料平台。该项目旨在利用综合实验-计算方法，提供在这种工艺下产生的共聚物的纳米级形貌的全面和基本知识。预计对多相聚合物高应变率行为的深入了解不仅将促进冷颗粒气体喷涂制造技术的发展，还将推进国防应用极端环境下材料使用的知识，从而促进科学的进步；促进国民健康、繁荣和福利；确保国防安全。该项目的教育和推广计划包括：课程更新，基于学生主导的小组项目和录像的新教学模式的开发，以及通过当地学校的专门课程为高中生介绍科学和工程。这项工作的目的是确定多相嵌段共聚物的高应变速率动态特性，这些共聚物由机械上独特的（硬/玻璃状和软/橡胶状）聚合物块组成，最终应用于冷颗粒气体喷涂制造。为了实现这一目标，将进行单共聚物微粒的高速碰撞实验。在精确的碰撞条件下，包括粒子？动能，角动量，温度，高应变率流变学和各种相变相和形态将被研究。研究小组还将在开发新的本构模型的基础上进行模拟。详细的高应变率变形动力学以及聚合物的纳米级特性对制造过程的贡献将进行定量研究。该项目的成功完成将为多相聚合物的高应变率特性建立一种新的微观方法。这项研究的数据将在一个可公开访问的数据库中提供，以便更广泛地传播。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。

In the cold particle gas spray manufacturing technique, sub- or super-sonic spraying of feedstock powders or micro-size polymeric particles can enable unique additive processing without the use of volatile organic compounds due to the extreme deformation of the microparticles during the collisions onto a substrate. As the consolidation occurs below the microparticles' melting temperature, extraordinary nanostructures created by the collision-induced deformation can remain and contribute to the performance of the end products. Thus, advanced additive manufacturing with the capability of nanoscale engineering of materials being deposited can be envisioned. Multiphase copolymers can serve as a promising material platform as they exhibit favorable inherent material behavior for cold particle gas spray process. This project intends to provide comprehensive and fundamental knowledge of the nanoscale morphologies of copolymers created under such process using an integrated experimental-computational approach. It is envisioned that a deeper understanding of high-strain-rate behavior of multiphase polymers will not only facilitate the development of the cold particle gas spray manufacturing technique but will also advance knowledge of materials use in extreme environments for defense applications, thereby promoting the progress of science; advancing the national health, prosperity, and welfare; and securing the national defense. The educational and outreach plan in this project includes: curriculum updates, development of a new teaching model based on student-led group projects and videography, and introduction to science and engineering for high school students through a specialized class at a local school.The objective of this work is to determine the high strain-rate dynamic characteristics of multiphase block copolymers consisting of mechanically distinctive (hard/glassy and soft/rubbery) polymer blocks, for eventual application in cold particle gas spray manufacturing. High-velocity collision experiments of single copolymer micro-particle will be performed to achieve this. Under precise collision conditions including particles? kinetic energy, angular momentum, and temperature, high-strain-rate rheology and various transitions in phase and morphology will be studied. The research team will also perform simulations based on the development of new constitutive models. Detailed high-strain-rate dynamics of deformation and the contributions from nanoscale characteristics of the polymers to the manufacturing process will be quantitatively investigated. The successful completion of this project will establish a new microscopic methodology to understand high strain-rate characteristics of multiphase polymers. The data from this research will be made available in a publicly accessible database for wider dissemination.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.