Surface treatments for improving the mechanical properties of carbon nanofiber/thermoplastic composites

Nanofiber-matrix adhesion was studied after surface treating carbon nanofibers using a variety of methods. Among as-grown fibers, those produced with longer gas phase feedstock residence times were less graphitic but adhered to the polypropylene matrix better, giving improved tensile strength and modulus. A modest degree of oxidation was also found to increase adhesion to the matrix and increase composite tensile strength, while extended oxidation attacked the fibers sufficiently to decrease composite properties. Two chemical treatments were found to be ineffective in increasing tensile strength or modulus.