Liquid Crystalline Matrix Polymers for Aramid Ballistic Composites

Five semi-flexible thermotropic liquid crystalline (LC) polyesters and poly(ester-amide)s were synthesized and used as matrix resins for Twaron™ aramid-based ballistic fabrics. The ballistic performance was investigated as a function of the neat resin content. For the most successful liquid crystalline polyester system, the effect of blending with styrene-ethylene-butylene-styrene (SEBS) and polyvinyl butyrate (PVB) rubber was also explored. The best neat resin V50 values were obtained for 20 wt% LC polyester (LCPE)-Twaron™ composites, that is, 418 m.s−1, whereas SEBS/LCPE and PVB/LCPE modifications resulted in maximum V50 values of 460 and 466 m.s−1, respectively. It was found that the ballistic impact resistance is strongly influenced by the elastic modulus of the resin component and to a lesser extent to the level of adhesion between the resin and fabric. The effect of resin content, resin strength, elongation-at-break, and resin toughness on the ballistic impact resistance was found to be small. The best ballistic protection could be obtained when the Young's modulus of the LC resin was in the range of 0.01–1 GPa. This result seems to be in agreement with existing inter-yarn friction models. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers