A-STAGE
An early of polymerization of thermosetting resins in which the material is still soluble in certain liquids and is fusible. Also called resole. See also B-stage, C-stage.

ABLATIVE
A material that absorbs heat through a decomposition process called pyrolysis at or near the exposed surface.

ACCELERATOR
A material which, when mixed with a catalyzed resin, will speedup the chemical reaction between the catalyst and resin; either in polymerizing of resins or vulcanization of rubbers. Also known as "promoter".

ACETONE
In an FRP context, acetone is primarily useful as a cleaning solvent for removal of un-cured resin from applicator equipment and clothing. VERY FLAMMABLE LIQUID.

ACI
The Air Catalyst Integrator valve is mounted on Binks spray guns. It functions as a point where catalyst and air are introduced, internally mixed and atomized in preparation for external mixing with the resin or gel coat in a spray pattern.

ACTIVATOR
See accelerator.

ADDITION
A polymerization reaction in which no by-products are formed.

ADDITIVES
Ingredients mixed into resin to improve properties.

ADHESION
The state in which two surfaces are held together at an interface by forces or interlocking action or both.

ADHESION FAILURE
A rupture of an adhesive bond that appears to be a separation at the adhesive/adherend interface.

ADHESIVE
A bonding substance which creates a molecular attraction, holding tow surfaces together.

AGING
The effect, on materials, of exposure to an environment for an interval of time; the process of exposing materials to an environment for an interval of time.

ALLOY
Made by mixing traditional polymers, which have already been formed. The mixing results in a single-phase material because the polymers have some interaction that combines them together. The properties of the alloy depend upon the physical interactions of the polymers.

AIR-BUBBLE VOID
Air entrapment within and between the plies of reinforcement; non-interconnected, spherical in shape.

AIR DRY
To cure at room temperature with the addition of catalyst but without the assistance of heat and pressure.

AIR-INHIBITED RESIN
A resin by which surface cures will be inhibited or stopped in the presence of air.

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

AIR VENT
Small outlet, to prevent entrapment of gases.

ALKYD PLASTICS
Plastics based on resins composed principally of polymeric esters, in which the recurring ester groups are an integral part of the main polymer chain, and in which ester groups occur in most cross links that may be present between chains.

ALLIGATORING
Wrinkling of the gel coat film resembling alligator hide. IT SUCKS.

AMBIENT
The surrounding environmental conditions such as pressure or temperature.

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

AMORPHOUS
Describes polymers that have no order to their molecules, thus no crystalline component.

ANISOTROPIC
The tendency of a material to exhibit different properties in response to stresses applied along axes in different directions.

ANISOTROPY OF LAMINATES
The difference of the properties along the directions parallel to the length or width into the lamination planes; or parallel to the thickness into the planes perpendicular to the lamination.

ANTIMONY TRIOXIDE
An additive used to give special flammability characteristics to a polyester.

ANTI-STATIC AGENTS
Agents which, when added to the molding material or applied on the surface of the molded object, make it less conducting (thus hindering the fixation of dust).

ARAMID
(Kevlar^(R)) Aromatic polyamide fibers characterized by excellent flame-resistantance, high-temperature, and electrical properties. Aramid fibers are used to achieve high-strength, high-modulus reinforcement in plastic composites.

ARCING
This spray method should normally be avoided as it consists of directing spray passes by gun rotation at the wrist (arcing), as opposed to the conventional stroke from the shoulder, keeping the fan pattern perpendicular to the mold.

AREAL WEIGHT
The weight of fiber per unit area (width times length) of tape or fabric.

ARTIFICIAL WEATHERING
Exposure to laboratory conditions, which may be cyclic, involving changes in temperature, relative humidity, radiant energy, and any other elements found in the atmosphere in various geographical areas.

ASH CONTENT
The solid residue remaining after a reinforcing substance has been incinerated (or strongly heated).

ASTM
American Society of Test Methods.

ASPECT RATIO
The ratio of length to diameter of a fiber.

ATOMS
The smallest possible unit of an element, which combines with another to form larger units; i.e., molecules.

AUTOCLAVE
A closed vessel that permits application of pressure and heat used for curing composites.

AUTOCLAVE MOLDING
A molding technique in which an entire assembly (layup) is placed into an autoclave at 50 to 100 psi, in order to consolidate layers of the part by removing entrapped air and volatiles. Usually includes application of heat to trigger cure of resin.

AUTO- IGNITION TEMPERATURE
The lowest temperature required to initiate or cause self-sustained combustion in the absence of a spark or a flame.

AUTOMATED TAPE LAYING
A fabrication process in which prepreg tape is laid side by side or overlapped in various configurations to form a structure.

AUTOMATIC MOLD
A mold (for injection or compression molding) that cycles repeatedly through the injection phase without human assistance.

AXIAL WINDING
A type of filament winding in which the filaments are parallel to the axis.

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Glossary Section (A) Last Updated: 9/3/99 1:18 PM

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