A constituent component that may be added to the composite matrix to modify its properties and in general, enhance its performance. Additives include catalysts, colorants, flame retardants and other ingredients that expand and improve the capabilities of the matrix.

Aspect Ratio

Ratio of length to diameter. For a composite, it refers to the specific ratio of the fiber or filler in the composite matrix.


A combination of one or more materials differing in form or composition on a macroscale. The constituents retain their identities; i.e. they do not dissolve or merge completely into one another, although they act in concert. Normally, the components can be physically identified and exhibit an interface between one another.


An inorganic addition to the composite matrix that may impart a variety of performance improvements such as shrinkage control, surface smoothness, water resistance and cost reduction or is added to lower cost or density.

Phenolic Resins

Phenolic composites have many desirable performance qualities including high temperature resistance, creep resistance, excellent thermal insulation and sound damping properties, corrosion resistance and excellent fire/smoke/ smoke toxicity properties.

Polyester Resins

Considered the “workhorse” of the composites industry, these resins offer a balance of properties (including mechanical, chemical, electrical) dimensional stability, cost and ease of handling or processing. Polyesters are versatile because of their ability to be modified or tailored. Ortho-and Iso-Polysters are two types of polyester resins formulated to enhance corrosion resistance.


Strong materials bonded to or into a matrix to improve mechanical properties. Materials, ranging from short fibers through complex textile forms, that is combined with a resin to provide the composite with enhanced mechanical properties.


A natural or synthetic viscous liquid, solid or semisolid, organic material of indefinite and often high molecular weight having a tendency to flow under stress, usually has a softening or melting range, and usually fractures conchoidally. Polymeric material that is rigid or semi-rigid at room temperature, usually with a melting-point or glass transition temperature above room temperature.


Resin that is not cross linked. Thermoplastic resin generally can be remelted and recycled.


Resin that is formed by cross linking polymer chains. A thermoset cannot be melted and recycled because the polymer chains form a three dimensional network.

Vinyl Ester Resins

Vinyl esters offer mechanical toughness and excellent corrosion resistance.