Past experience has shown that the performance of high strength fibers can degrade due to exposure to moisture, heat, and mechanical damage with catastrophic consequences. Currently, it is not possible to accurately predict the long term performance of a textile or fiber composite used for ballistic protection. Quantitative measurements of molecular structure, oxidation, and mechanical wear of chain scission in fibers are required to support the development of predictive models. This project seeks to utilize and develop novel chemical and mechanical techniques to connect localized molecular changes such as the formation of voids or kink bands to fiber mechanical and viscoelastic properties under quasi-static and dynamic deformation through novel techniques such as positron annihilation lifetime spectroscopy (PALS). In addition, the development of molecular models to predict the change stiffness and strength in single fibers, fiber bundles, fabric, and composites will be explored.

 

key words

High strength fibers; Ballistic armor; Aging; Carbon nanotubes; Graphene; Polyethylene; Kevlar; Dynamic impact; Durability;

Citizenship:  Open to U.S. citizens

Level:  Open to Postdoctoral applicants