Development of ballistic armor from kevlar fiber and polybenzoxazine alloys

This study aims to develop a light weight ballistic armor from Keviar[super subscriptTM] –reinforcing fiber having polybenzoxazine alloys as a matrix. Polybenzoxazine (BA), a class of phenolic resein, possesses several outstanding properties for being used as a composite matrix such as ease of synthesis, near-zero shrinkage, lack of by-product upon curing. low A-stage viscosity, high flame resistance, and high thermal and mechanical integrity. In addition, a number of recent reports reveal that polybenzoxazine can be alloyed with various types of resins to further broaden its useful properties. In this work, urethane elastomer (PU) is used to enhance toughness of the polybenzoxazine and its effects on the ballistic characteristics of the alloy matrices reinforced with Kevlar[super subscriptTM] are investigated. The experimental results reveal that the curing peak of the matrices shifts to higher value with increasing the urethane mass fraction in the BA/PU resin mixtures. The glass transition temperature increased from 175℃ in the Kevlar[super subscriptTM] -reinforced polybenzoxazine to 193℃ in the Kevlar[super subscriptTM]-reinforced 80/20 BA/PU and also up to 235℃ in the Kevlar[super subscriptTM]-reinforced 60/40 BA/PU. For mechanical properties, the increase of the elastomeric PU content showed the expected increase of toughening behavior of the compostites. The storage modulus of the Kevlar[super subscriptTM]-reinforced BA/PU composite decreased from 16.4 GPa of the polybenzaxazine matrix to 2.8 GPa of the 60/40 BA/Pu alloys. A ballistic test was performed on a Kevlar[super subscriptTM]-reinforced composite using a 9 mm handgun and it was found that the optimal composition of BA/PU alloys should be approximately 20 by weight of the PU. The extent of the delaminated area and interfacial fracture were observed to change with the varied compositions of the matrix alloys. The appropriate thickness of Kevlar[super subscriptTM]-reinforced 80/20 BA/PU composite panel was 30 plies and 50 plies to resist the penetration from the ballistic impact of levels II-A and III-A, respectively. Moreover, the arrangement of composite panels with the thinker and higher stiffness panel at the front side showed the damage area of composites of best efficiency for ballistic penetration resistance.