Composite Armor Performance Enhancement by Tethered Polymer Chains at the Fiber-Matrix Interface

摘要

The aim of this project was to investigate the use of tethered chains to increase the energy absorption capability of the fiber-matrix interface, and thereby enhance the ballistic protection properties of fiber composites. The governing strategy was to tailor the discontinuous fiber-matrix interface so as to introduce a volume of interaction capable of providing additional, molecular- level energy dissipation mechanisms to the composite during impact. This was accomplished by covalently tethering compatible polymer chains to the surface of the reinforcing phase, while leaving the other end of the chains free to interact with the adjacent matrix phase. The project encompassed a spectrum of experimental work involving synthetic preparation of end-functional polymer chains, derivitization of the glass surface for chain attachment, characterization of the resulting tethered layer, and mechanical evaluation of both isolated and distributed interfaces at low and high rates. The effectiveness of the tethered chain concept for the improvement of impact performance was clearly demonstrated for isolated interfaces at both low 10(exp -4 /sec) and high (1 /sec) test rates. High rate compressive tests performed on composites containing distributed interfaces showed no improvement in performance, however. This latter result was attributed to the matrix- dominated nature of impact failure encountered during the compressive testing.