Polymer Engineering and Science, Vol.60, No.7, 1546-1555, 2020
Injection moldable rate stiffening re-entrant cell arrays for wearable impact protection
The rigid cellular materials widely used for personal impact protection can be effective but tend to be inconveniently thick, and to be less effective after a first impact. A macroscopically structured panel material, molded as a two-dimensional matrix of re-entrant cells, has been specifically designed and optimized for body-worn protection. These panels are injection molded from a blend of rate-stiffening polyborodimethylsiloxane with a thermoplastic elastomer, optimized to minimize the impact force transmitted to the anvil in standard drop-weight tests even as monolithic slab specimens. The concurrently designed, impact-protective molded panels offer equivalent protection in thinner, lighter, and more wearable layers. Their re-entrant cellular structure and rate-stiffening material allow them to conform easily to individual wearers and to allow free movement at normal rates, while offering enhanced protection under one or more impacts at the same location.