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Effect of Aging on Unidirectional Composite Laminate Polyethylene for Body Armor



Amy Engelbrecht-Wiggans, Ajay Krishnamurthy, Amanda L. Forster


Ballistic-resistant body armor has increasingly been using flexible unidirectional (UD) composite laminates that comprise multiple layers in the armor construction. Each UD layer contains high-performance fibers held in place using very low modulus binder resins. Laminates are then made from orthogonal stacks of these layers, and these laminate-based armor packages offer significant performance advantages over standard woven materials. When designing any armor system, the long-term reliability of the armor materials is critical, particularly with regards to stability with exposure to temperature and humidity, as these are known causes of degradation in commonly-used body armor materials. To better inform future armor designers, this work investigates the tensile behavior of an ultra high molar mass polyethylene (UHMMPE) flexible UD laminate aged for up to 350 d at two accelerated conditions of 70 °C and 76 % relative humidity (RH), and 70 °C in a desiccator. Tensile tests were performed at two different loading rates. The effect of aging on the mechanical properties of the material resulted in less than 10 % degradation in tensile strength, indicating high reliability for armor made from this material.


Composite laminate, flexible composite, strip tensile testing, body armor, polyethylene, hydrothermal ageing


Engelbrecht-Wiggans, A. , Krishnamurthy, A. and Forster, A. (2023), Effect of Aging on Unidirectional Composite Laminate Polyethylene for Body Armor, Polymers, [online],, (Accessed June 16, 2024)


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Created March 8, 2023, Updated March 20, 2023