Graphene and carbon nanotubes for the synergistic reinforcement of polyamide 6 fibers

Poly(styrene-maleic anhydride) functionalized graphene (FG) and functionalized carbon nanotubes (FCNTs) were fabricated using in situ polymerization. The FG and FCNTs were used in the in situ ring-opening polymerization of ε-caprolactam to form polyamide 6 (PA6)/FG/FCNTs composites. Both PA6 and the composite fibers were melt-spun in a piston spinning machine. The structure and properties of the composites and the fibers were characterized. The experimental results demonstrate that the mixture of graphene and carbon nanotubes exhibits good dispersion in a PA6 matrix. No obvious aggregation of graphene or CNTs was observed inside the composite fibers. The mechanical properties of PA6 are improved by inserting FG/FCNTs into the composite fibers, in particular, the tensile strength of composite fiber containing FG (0.2 wt%)/FCNTs (0.3 wt%) is 2.4 times that of pure PA6, and Young’s modulus is 132 % higher than that of the control. The crystallinity of the composite fibers is also enhanced. With the improvement of the tensile strength and Young’s modulus of PA6, its application will be expanded.