Additives

Although additives compose small percent by volume of materials used in composites they allow modification of a materials properties and can increase performance. Additives play a major role in the curing of thermoset resins, for some increasing the speed of the curing process and for others decreasing the speed of curing. Additives are also used to provide color, and can be mixed with the resin, or applied later in a gel coat. Other additives, such as Teflon, are used in molding processes to facilitate the release of the product from the mold.

Additives perform a variety of functions when used in composites. Some common functions include: surface smoothing and reducing resin-shrink, increasing fire resistance, reducing the amount of trapped air within the composite, suppressing emissions, and viscosity control. Other functions aditives perform are increasing electrical conductivity of the composite (also used to allow for electromagnetic interference shielding), inhibiting oxidization of the polymer, reducing static buildup, and providing surface lubrication.