Coating of carbon fibers with adhesion-promoting thin polymer layers using plasma polymerization or electrospray ionization technique-A comparison

Plasma polymers and electrospray-ionization (ESI) polymer layers are compared for most efficient adhesion promotion in carbon fiber-epoxy resin composites. The ultra-thin ESI layers (2–30 nm) of commercial poly(acrylic acid) and poly(hydroxyethylmethacrylate) produce an significant increase of adhesion measured by single-fiber pull out tests. However, plasma treatment has also advantages, such as simultaneous activation of the fiber substrate. Chemical structure and composition are rather far from the regular structure of commercial polymers as deposited by ESI processing.