Transcrystallinity in surface modified aramid fiber reinforced nylon 66 composites

Aramid (kevlar-49) fibers were surface treated by two different methods to induce roughness and then used to produce unidirectional nylon 66 based composites. The transcrystallinity generated around the treated fibers was characterized by SEM and polarized light microscopy and compared with the regular transcrystalline layers produced by pristine aramid under the same processing conditions. The treated fibers generated a double transcrystalline layer, the inner layer being thinner and more compact than the regular nylon 66 transcrystallinity. In addition, mechanical testing of the composites showed the longitudinal Young's modulus of the treated fiber composites to be significantly higher than the control in a wide range of fiber volume fractions.