Effect of Solvent Processing of Coatings on Failure in Anti-ballistic Materials

点击翻译按钮获取中文摘要

Anti-ballistic lenses for eyewear are incredibly crucial for armed personnel in the field. This project's goal is to determine what are the chemical causes for failures of such lenses - specifically the coating solvent effect on the lens substrate. Generally, poly(urethane)s (PU) or poly(amide)s PA have exhibited better ballistic performance compared to poly(carbonate) (PC) or poly(methyl methacrylate) (PMMA) resins used previously for the substrate. Trogamid CX 7323 (Evonik) is one of these grades of PA and they have been available since the early 1970s but have only relatively recently been studied as alternatives to PC and PMMA. Trogamid CX-7323 was reported to exhibit ductile failure upon ballistic impact, like PC. The uncoated material fails in a brittle mode and often fails with multiple shots. Coated samples fail in a brittle fashion as well. This failure was surmised to be due to two sources: multiple shots or chemical interactions. In the case of multiple shots, the first shot starts the deformation and the second propagates it. To determine the potential causes of failure by chemical means, we will examine specifically the coating process and the effect of solvent on the mechanical performance of the material (thermal transitions such as glass transition (Tg)). Solvents will be screened (selection will be based on industrial partner's experience). The industrial partner has been a leading supplier of anti-ballistic eyewear for military personnel to Canadian armed forces and understanding failure modes in such materials can eventually lead to improved eyewear materials, which can lower fatality rates and reduce the extent of injuries to personnel in the field.