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A

ABS: Acrylonitrile Butadiene Styrene (Thermoplastic Resin).

Ablative Plastic: A material that absorbs heat (with low material loss and char rate) through a decomposition process (pyrolysis). Absorption takes place at or near the surface exposed to the heat.

Abrasion: Wearing away by friction. Glass is highly resistant to abrasion from other materials, but can be damaged through contact with itself. Lubrication during processing and fabrication helps prevent abrasion.

Accelerated Test: Procedure in which conditions are magnified to reduce the time required to obtain a result, or to reproduce the deteriorating effects of normal service conditions in a very short time period.

Accelerator (Promoter): A highly active oxidizing agent used to speed up the chemical reaction (curing) between a catalyst and resin. Examples include diethylaniline, cobalt naphthanate and cobalt octoate.

Activator: See Accelerator.

Acoustic Emission: The amount of integrity in a material after it has been stressed, as determined by sound emission. Ideally, emissions can be correlated with defects and/or early failure.

Acrylic: Thermoplastic polymer made by the polymerization of esters of acrylic acid and its derivatives.

Actual End Count: The number of bundles or splits that are actually counted in one doff of roving. (This is less than the theoretical end count due to splitting efficiencies of less than 100%).

Addition Polymerization: Chemical reaction in which simple molecules (monomers) are added to each other to form long-chain molecules (polymers) without byproducts.

Additive: A material used to modify the properties of polymer resins. Examples include plasticizers, initiators, light stabilizers and flame-retardants.

Adhesion: The state in which two surfaces are held together by an interlocking action or force.

Adhesive: A film, liquid or paste capable of holding the surfaces of two materials together.

Admixture: Addition and homogeneous dispersion of discrete components, before cure.

Aggregate: Hard, coarse material usually of mineral origins used in composite tools. Also used in flooring or as a surface medium.

Aging: The process of exposing materials to an environment for an interval of time.

Air-Bubble: A localized, non-interconnected, spherically shaped entrapment of air within and between the plies of reinforcement.

Air Splice: The coupling made by a jet of air to entwine/snarl two roving doffs together. The air splice is used instead of a knot.

Air Vent: Small outlet to prevent entrapment of gases in a molding or tooling fixture.

Alkyd Plastics: Resin composed principally of polymeric esters, in which the recurring ester groups are an integral part of the main polymer chain or are part of the cross links present between chains.

Alligatoring: Visible cosmetic defect in exposed gel coat resembling wrinkled or alligator-like skin.

Alloy: In plastics, a blend of polymers or copolymers blended with other polymers or elastomers under select conditions.

Ambient: Surrounding environmental conditions, such as pressure, temperature, or relative humidity.

Amine Resins: A synthetic resin derived from the reaction of urea, thiourea, melamine or allied compounds with aldehydes, particularly formaldehyde.

An Isotropic: Exhibiting different properties when tested along axes in differentdirections. see An Isotropic laminate

An Isotropic Laminate: A laminate whose properties are different in different directions.

Angle-Ply Laminate : A laminate with fibers of adjacent plies oriented at alternating angles.

Antioxidant: Substance that, when added in small quantities to resin, prevents oxidation and degradation while maintaining the resin’s properties.

Antistatic Agents: Agents added to a molding material or applied to the surface of a molded object to make it more conductive and prevent the fixation of dust or buildup of electrical charge.

Arimid: A highly oriented organic material derived from polyamide with an aromatic ring structure that is used primarily as a high-strength, high-modulus fiber. Examples include Kevlar and Nomex.

Arc Resistance: Ability to withstand exposure to an electric voltage. Also, the total time in seconds that an intermittent arc may play across a plastic surface without rendering it conductive.

Ash Content: Proportion of solid residue remaining after a reinforcing substance has been incinerated (charred or intensely heated).

Aspect Ratio: Ratio of length to diameter of a fiber.

A-Stage: Early stage in the polymerization reaction of certain thermosetting resins (especially Phenolic) in which the material, after application to the reinforcement, is still soluble in certain liquids and is fusible. Also called resole. see B-Stage and C-Stage

ASTM: American Society of Test Methods.

Autoclave: Closed vessel for conducting and completing a chemical reaction or other operation under pressure and heat.

Autoclave Molding: Process in which an assembly is placed in a heated autoclave, usually at 50 to 200 psi, after lay-up, winding or wrapping. Additional pressure permits higher density and helps remove volatiles from the resin. Lay-up is usually vacuum bagged with a bleeder and release cloth.

Autosprue™: Automatic gate at the inlet sprue of the mold that eliminates the need to remove the resin supply during injection.

Axial Winding: Filaments that are wound parallel or at a small angle to the axis (0° helix angle).