Reuse of p-aramid from industrial waste as reinforcement fiber in polyamide 6.6

P-aramid fibers are well known for their excellent combination of specific tensile strength and elastic modulus. The fact that p-aramids do not melt makes their mechanical recyclability more difficult, and leads to more waste being incinerated or going to landfill. As an alternative option, this work evaluated the feasibility of reusing p-aramid fibers as mechanical reinforcement in polyamide 6.6 (PA66) matrices. With the objective of improving interfacial adhesion, PA66/aramid-fiber composites were prepared with fiber concentrations of 5 and 10 wt% using two treatments: the fibers were washed with hexane and the fiber surfaces were treated with a NaOH solution under different treatment conditions (the treatment time and the concentration of the NaOH solution were varied). The mechanical properties were evaluated via tensile, bending and impact tests, while the morphological properties were assessed by scanning electron microscopy (SEM). The SEM images showed that, with the exception of the washing with hexane, the surface treatments improved the interfacial adhesion. However, this improvement was not reflected in the mechanical properties because the NaOH treatment also decreased the tensile strength of the fibers. The addition of 10 wt% of p-aramid fibers had positive effects on the reinforcement, therefore, this composite could be used in future engineering applications.