BYK Additives & Instruments

Product Highlight
BYK-C 8013

World debut: BYK develops the first coupling agent for carbon fibers

  • Suited for all types of carbon fiber
  • Improves flexible and transverse tensile strength by up to 70 percent
  • Liquid additive, easy to incorporate


BYK-C 8013 is a solvent-free, polymeric coupling agent for improving the mechanical strength of carbon-fiber-reinforced, radical-curing systems, and it is the world’s first coupling agent for carbon fibers.

It is used in vinyl esters and unsaturated polyester resins that are processed to composite parts using carbon fibers. The cross-fiber strength is greatly improved, making far greater design freedom possible.

BYK-C 8013 increases both the transverse tensile strength and the flexible strength of the composite by means of improved fiber-matrix bonding. The chemical structure of the additive provides simultaneous adhesion to the fiber and to the resin matrix. This unique property makes changes in the component design possible, and it enables particularly durable components to be manufactured. Especially in hot-curing processes such as SMC/BMC, pultrusion, prepreg or RTM, BYK-C 8013 brings about increases in strength of up to 70 percent.

No coupling effect
Coupling effect with BYK-C 8013

The reactive additive can be introduced to the size during fiber production or to the resin shortly before processing. In subsequent, so-called “second sizing”, BYK-C 8013 can, for example, be applied to the fiber in a spraying process, without the need to remove the first sizing beforehand.

BYK-C 8013

THE additive portfolio for fiber reinforced composites

In order to exploit the full potential of modern composites based on thermoplastics or duroplastics, the use of special additives provides great benefits. They are even used in starting raw materials for component manufacturing. For example, in sizing they are incorporated to improve processing or bonding of the fibers to various matrix systems. When directly used in resins, additives can modify a multitude of properties. In the finished formulation, they can significantly improve or, depending on the process, even make some processing properties feasible. Finished components have better properties or surfaces if additives have been used.

As one of the world’s leading supplier of plastics additives with longstanding experience in the field of composites, BYK is your partner, working together to develop the best technical solution.