GOALI: Tomography and X-ray Interferometry of Flame Retardants and Additive Manufacturing

获得这一奖项后，化学系的化学测量和成像计划以及工业创新与合作司(IIP)的学术联系机会(GOALI)计划正在支持路易斯安那州立大学(LSU)的Les Butler教授和Albemarle Corporation的Jonathan McCarney博士开发新的X射线成像方法，以评估聚合物(塑料)中阻燃剂(FR)的性能。目前，使用本生燃烧器、秒表和棉垫对阻燃剂进行评估的方法包括保险商的《设备和电器部件用塑料材料的可燃性测试标准》(UL 94)。UL方法是实用的，但不能提供有效开发新型阻燃剂的化学/物理洞察力。巴特勒教授和麦卡尼博士的实验室正在开发一种方法，通过快速记录燃烧期间的二维X射线图像(即电影)来评估阻燃剂。生成的电影可以直观地显示化学和物理过程，如颗粒溶解、气泡产生、熔融塑料的流动、炭层的发展和炭层中的微裂缝。此外，与传统测试相比，X射线图像为更深入地评估新型阻燃材料的性能提供了定量信息。除了FR测试，两个小组还将这种新的X射线成像技术应用于3D打印，在3D打印中，新的阻燃材料被结合到消费物品中。巴特勒教授正积极通过NSF I-Corp计划向理科学生拓展工作，该计划将无损化学测试、3D打印和材料开发相结合，为研究生、本科生和当地高中生提供了许多研究和教育机会。巴特勒小组正在与高级光子源合作开发的软件将通过开源断层成像软件包TomoPy项目向公众提供。路易斯安那州立大学正在开发的X射线成像法使用巴特勒小组最近建造的两个新的基于光栅的干涉仪。干涉仪有两种工作模式：单次扫描速度模式和阶梯光栅模式，以获得更好的图像质量。单镜头干涉测量仪在测量过程中提供吸收、相位和散射成像方式，其快速的图像采集速度使X射线电影记录在改进的UL 94测试中起作用的阻燃剂，并直接观察新一代阻燃剂的性能。同样的成像方法也适用于熔融沉积建模(FDM)，也称为3-D聚合物打印。目标是开发评估阻燃剂对3D打印质量的影响的程序，其中X射线胶片显示由阻燃剂/聚合物混合物组成的细丝的原位熔融沉积建模，以评估兼容的温度、流量和打印头速度。然后，这些知识将被用于探索打印对象中阻燃剂的三维结构的新选择。

With this award, the Chemical Measurement and Imaging Program in the Division of Chemistry and the Grant Opportunities for Academic Liaisons with Industry (GOALI) program in the Division of Industrial Innovation and Partnerships (IIP) are supporting Professor Les Butler at Louisiana State University (LSU) and Dr. Jonathan McCarney at Albemarle Corporation to develop new X-ray imaging methods to assess the performance of flame retardants (FR) in polymers (plastics). Currently, flame retardants are assessed with methods such as the Underwriter Laboratory Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances (UL 94) using a bunsen burner, a stopwatch, and a cotton pad. The UL method is practical, but does not provide a chemical/physical insight into the effectively development of new flame retardants. The approach under development in the labs of Professor Butler and Dr. McCarney evaluates flame retardants by fast recording 2-D x-ray images (i.e. movies) during the burning period. The resulting movie enables direct visualization of chemical and physical processes, such as particle dissolution, gas bubble generation, the flow of the melting plastic, char-layer development, and micro-cracks in the char layer. In addition, the x-ray images provide quantitative information for more in-depth performance evaluations of new flame retardant materials relative to traditional tests. Beyond FR testing, both groups are also applying this new x-ray imaging technique in 3-D printing where new flame retardant materials are incorporated into consumer objects. Professor Butler is actively engaged an outreach effort to science students through the NSF I-Corp program where the combination of non-destructive chemical testing, 3-D printing, and materials development provides many research and educational opportunities to graduate, undergraduate and local high school students. The software under development in the Butler group, in collaboration with the Advanced Photon Source, will be made available to the public through the TomoPy project, an open source tomography software package.The X-ray imaging method under development at LSU uses two new grating-based interferometers recently constructed by the Butler team. The interferometers is operated in two modes: single-shot for speed, and stepped-grating for better image quality. The single-shot interferometry provides absorption, phase, and scattering imaging modalities during the measurements and its fast speed in image collection enables X-ray movie recording of flame retardant in action in a modified UL 94 test and direct observation of the performance of new-generation flame retardants. The same imaging methods is applied to fused deposition modeling (FDM), also known as 3-D polymer printing. The goal is development of procedures for assessing flame retardant impact on the quality of the 3-D print where x-ray movies show in situ fused deposition modeling of filaments composed of flame retardant/polymer blends to assess compatible temperature, flow, and printhead speeds. The knowledge is then to be used in exploring new options for 3-D structure of flame retardants in the printed object.