Micro-buckling resistant unidirectional glass fiber composites with excellent transverse and longitudinal flexural properties from cross-linking by nano-/micro-aramid fibers

This study aims at obtaining an effective structural design strategy for stronger and more reliable Unidirectional glass fiber (UD-GF) composites by in-situ formed cross-linking from randomly distributed nano-/micro- Aramid pulp (AP) fibers. The flexural strength and stiffness have shown substantial improvements in both the transverse and longitudinal directions due to the AP cross-linking and the "brick-slurry" structure. With AP of 8 g/m2, up to 60-70% improvement in flexural strengths (both transverse and longitudinal directions) and up to 20-37% improvement in “effective modulus” have been observed. The noticeable longitudinal improvements have been attributed to the resin reinforcement and interlayer cross-linking provided by ultra-thin AP interlayers, and the resultant improvement in micro-buckling resistance under compression. Since sparsely distributed nano-/micro-AP can be readily incorporated in pultrusion and pre-preg manufacturing processes, this study is not only important for micro-mechanism study, but also provides a plausible improvement in manufacturing.