High-performance materials are used to protect wearers from injury due to ballistic and stab threats, as well as other potentially life-threatening incidents. The mechanical behavior necessary to prevent injury from these threats is multifaceted and dependent on the chemical and structural properties of these materials. The Security Technologies Group develops the measurement science necessary to understand the chemical and structural properties of these materials and how these properties are affected by environmental exposure and wear.
The body-armor community generally bases armor design on empirical models that do not directly relate molecular properties to performance. Aramid, aramid copolymers, and UHMWPE fibers are highly oriented, anisotropic fibers that require specialized characterization techniques. In addition, there is limited publicly-available data on degradation mechanisms in these highly aligned systems. Fundamental understanding of the impact of material properties on short and long-term material performance is limited by this lack of available data. Also, interacting factors (i.e. kink band formation) have not been considered in the context of broader performance degradation.
The STG conducts and performs fundamental research to advance the understanding of these high-performance materials, which can be difficult to study due to their high strength and anisotropic molecular orientation. The goal of this work is to enhance the body armor community’s understanding of the relationship between properties and performance in high performance materials used in protective applications. This work falls under several different project areas:
-Understanding the ageing mechanisms that degrade high-performance materials
-Development of novel measurement tools to understand structure-property relationships in materials
-Investigation of the links between material properties and ballistic performance
An activation energy for thermooxidation of ultrahigh molecular weight polyethylene fibers was calculated from ageing experiments performed by our laboratory. This was the subject of a paper published in Polymer Degradation and Stability in 2015. Continued work with this material is under way.