A New Class for Armour Materials from Recycled Kevlar
Aline Marques de Oliveira1; Elvis Carneiro Monteiro1; Viviane Cristina Munhoz1; Antonio Ferreira Ávila1
1 Universidade Federal de Minas Gerais
doi:10.20906/CPS/COB-2015-1976
Resumo
A critical issue on ballistic materials, in addition to the impact resistance, is weight. The usage of aramid reinforced composites presents one of the best protections to weight ratio for impact applications, however the high cost of these fibers is a disadvantage. Moreover, due to international regulations and for safety reasons, all bulletproof vests must be replaced every five years. It is estimated that in Brazil between 75.000 and 100.000 bulletproof vests must be replaced each year. As these bulletproof vests cannot be discarded without proper treatment, a recycling procedure is urgent. This paper investigates new applications for Kevlar fabrics from discarded bulletproof vests and its application as ballistic shield. The new ballistic composite material is a hybrid laminate, where recycled aramid fibers are consolidated by epoxy resin. The Kevlar fabrics from bulletproof vests have an areal density of approximately 300 g/m2 (12.6 oz./yd2). The epoxy system is an amine-cured bisphenol-A-diglycidyl ether epoxy resin from Barracudatec Inc., while the nano-reinforcement is a shear thickening fluid (STF) composed of 60wt% silica nano-particles (70-100 nm), obtained from Nissan Chemicals, and 40wt% ethylene glycol used as medium to disperse the silica particles. To improve the wettability of the Kevlar fabrics with STF's, these dispersions were diluted with ethanol before application onto the Kevlar fabrics. The STF treated fibers were dried at 80 °C for 30 min in a hot air oven to evaporate ethanol. As this research deals with two different levels of analysis, i.e. the first one on nanoscale and the second one on macroscale, the experimental investigation must be divided in two different time frames. At nanoscale, the nanostructures are investigated with scanning electron microscope. At macro-scale, ballistic tests are based on the NIJ Standard-0101.04. Two types of ammunition are considered, i.e. 9 mm Full Metal Jacketed (FMJ) and 357 Magnum Jacketed Soft Point (JSP). To be able to correlate the ballistic
Palavras-chave: composite armour; ballistic performance; shear thickening fluid; recycled aramid