Liquid Crystalline Single-Polymer Short-Fibers Composites

Single-polymer short-fibers composites (SPSFCs) were obtained by including Vectran® fibers in a Vectran® matrix. A thermal annealing treatment was optimized to increase the melting temperature, mechanical properties, and thermal stability of pristine Vectran® fibers, and a two-step process was successfully developed to consolidate SPSFCs containing up to 30 wt.% of reinforcement. The composites exhibited a remarkable improvement of the tensile modulus (up to 161%) and a decrease of elongation at break in comparison with the unfilled matrix. A slight decrease of the composites tensile strength was also observed which suggested an investigation of the matrix–reinforcement interfacial adhesion. SEM observations evidenced some pull-out phenomena, indicating a poor interfacial adhesion. A plasma surface treatment on the reinforcing fibers was performed in order to increase the interfacial adhesion in the composites. The results showed an increase of almost 180% in the tensile modulus compared with the unfilled matrix and fiber breakage as main fracture mechanism.