Abstract: A sizing formulation adapted for use with carbon fiber yarn comprising an aqueous dispersion of a film-forming, heat-reactive resin having a Tg below about -50.degree. C. and a water-dispersible ethoxylated alkyl phenol provides yarn having improved resistance to abrasion, less breakage and low fuzz formation, permitting substantial handling of the fiber in fabrication and weaving operations with reduced losses. In addition, the sizing may be readily removed thermally without the production of noxious byproducts when deemed necessary for use in further processing and impregnation operations.

Abstract: Carbon fibers may be made by a process comprising:overwrapping a multifilament polyacrylonitrile tow with a thread of material to maintain the tow as an integral bundle, followed bystabilizing said tow by heating in an oxidizing atmosphere at a temperature between about 180.degree. and about 400.degree. C., thereby oxidizing the filaments comprising said tow, followed bycarbonizing the tow thus stabilized by heating at a temperature sufficient to effect carbonization, thereby forming a carbon fiber.The carbon fibers may be used to make reinforced composites in thermoplastic or thermosetting matrix resins, particularly prepreg.

Abstract: An apparatus is disclosed for continuously applying a treating medium onto a moving substrate in a turbulent manner. The apparatus is provided with a chamber through which the substrate and the treating medium are passed. Both the upper and lower portions of the chamber each have at least one cavity which is perpendicular to the direction of travel of the substrate, wherein the respective cavities of the upper and lower portions are coaxial with one another. Each cavity contains an applicator which is capable of turbulently applying the treating medium onto the substrate. A method of treating a substrate with a treating medium using this apparatus is also disclosed. By means of the apparatus and method disclosed, a substrate can be treated in a more controlled and efficient manner.