Coated fibers, methods of making, and composite materials reinforced with coated fibers

A method of manufacturing one or more coated natural fibers, the method consisting of the following steps performed in sequential order in a continuous process one or more times:

• providing at least one fiber having a surface, the at least one fiber does not comprise a synthetic fiber, the at least one fiber having a composition selected from the group consisting of flax, wood, jute, kenaf, hemp, cotton, coir, bamboo, abaca, ramie, sisal, silk, wool, camel hair, angora, alpaca fiber, mohair, and a blend thereof;
• optionally, pretreating the surface of the at least one fiber using atmospheric pressure plasma;
• and
• applying a coating formulation consisting essentially of a silane coupling agent or an organosilicon compound in the form of a pure chemical, a mixture, a solution, or a dispersion directly to the surface of the at least one fiber along with simultaneously exposing the coating formulation on the surface of the at least one fiber to an atmospheric pressure plasma, thereby, bonding and curing the coating formulation on the surface of the at least one fiber to form the one or more coated natural fibers without the need for a photoinitiator.