Industry Glossary - A

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.

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

Acrylonitrile Butadiene Styrene (Thermoplastic Resin).

A highly active oxidizing agent suspended in a liquid carrier used in conjunction with a catalyst to produce internal heat in a liquid plastic to cure it. Examples are diethylaniline, cobalt naphthanate and cobalt octoate.

(Styrene solubility) – The percentage of the sizing on the glass fiber that is dissolved off the strand in acetone (or styrene) after soaking in the solvent.

Measure of integrity of a material, as determined by sound emission when a material is stressed. Ideally, emissions can be correlated with defects and/or incipient failure.

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

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 that 100%).

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

Any number of materials used to modify the properties of polymer resins, such as plasticizers, initiators, light stabilizers and flame-retardants.

Substance capable of holding two materials together by surface attachment. Adhesive can be in film, liquid, or paste form.

Addition and homogeneous dispersion of discrete components, before cure.

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

Effect on materials of exposure to the environment. The process of exposing materials to an environment for an interval of time.

Void air entrapment within and between plies of reinforcement or within a bond line or encapsulated area; localized, non-interconnected, spherical in shape.

The coupling between two roving doffs which is made by a jet of air entwining/snarling the two strands together. The air splice is used instead of a knot.

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

Visible cosmetic defect in exposed gel coat which looks like wrinkled or alligator skin.

In plastics, a blend of polymers or copolymers with other polymers or elastomers under selected conditions.

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

Exhibiting different properties when tested along axes in different directions.

One in which the properties are different in different directions.

Laminate having fibers of adjacent plies oriented at alternating angles.

Substance that, when added in small quantities to resin, prevents oxidative degradation and contributes to the maintenance of its properties.

Agents that, when added to a molding material or applied to the surface of a molded object, make it more conducting, thus hindering the fixation of dust or the buildup of electrical charge.

Ability to withstand exposure to an electric voltage. The total time in seconds that an intermittent arc may play across a plastic surface without rendering the surface conductive.

Type of highly oriented organic material derived from polyamide but incorporating aromatic ring structure. Used primarily as a high-strength, high-modulus fiber. Kevlar and Nomex are example of arimid.

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

Ratio of length to diameter of a fiber.

American Society of Test Methods.

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

Process in which, after lay-up, winding, or wrapping, and entire assembly is placed in a heated autoclave, usually 50 to 200 psi. Additional pressure permits higher density and improved removal of volatiles from the resin. Lay-up usually vacuum bagged with a bleeder and release cloth.

Automatic gate at the inlet sprue of the mold which eliminates the need to remove the resin supply during the injection process for flushing. See: Autosprue

In filament-wound reinforced plastics, a winding with the filaments parallel or at a small angle to the axis (0� helix angle).