An additive to polyester resin that speeds up the cure and is usually used in conjunction with a promoter. See Promoter
A ketone group solvent that is used to dissolve polyester resins. Used to a large extent for clean up of tools in fiberglass operations.
A bonding substance that creates a molecular attraction, holding two surfaces together.
A resin or paint that dries through the loss of solvent or monomer.
Resin that cures with a tacky surface due to their air inhibiting their cure in a thin surface layer.
Any number of materials used to modify the properties of polymer resins. Categories of additives include reagents, fillers, viscosity modifiers, pigments and others.
A visible cosmetic defect in the exposed gel coat that looks like wrinkled or alligator skin.
Fire retardant additive for use with resins containing chloride or bromine.
Aromatic polyamide used to make high strength fibers, commonly known as Dupont KevlarTM.
A spray gun stroke that moves the gun through an arc, thus changing the spray angle throughout the stroke. An arcing stroke should be avoided for proper spraying technique.
Molding technique where a vacuum bagged composite lay-up is placed in a pressure chamber and heated to cure. A pressure of 50 to 100 psi consolidates the laminate.
The temperature at which a substance experiences ignition in the absence of a spark or flame.
An airtight film used to apply atmospheric force to a laminate. See Vacuum Bag Molding and Pressure bag.
A measure of surface hardness made with a Barcol Impressor instrument in accordance with ASTM D-2583. The harness value can be used as an indication of the degree of cure of FRP laminates.
An initiator for curing polyester resin. BPO is used with aniline accelerators or where heat is used to cure the resin.
Reinforcing fibers that are arranged in two directions, usually at right angles to each other.
A resin soluble adhesive that secures the random fibers in chopped strand mat or continuous strand roving.
Layer of porous material placed in a vacuum bag to absorb excess resin and allow air and gas to escape.
Stress required (as measured by load/bond area) to separate a layer of material from another material to which it is bonded. Also, amount of adhesion between bonded surfaces.
Separation or breakage of fibers when edges of a composite part are drilled or cut.
Fabric reinforcement extended over a curved edge that does not come into contact with rest of the composite.
Failure mode usually characterized by fiber deflection rather than breaking.
BULK MOLDING COMPOUND
Premixed blend of thermosetting resin, reinforcements, catalysts and fillers for use in compression, transfer, or injection molding process.
A void formed within a composite that may be the result of either trapping air in a laminate, or chemical action within the laminate.
The process of pouring a mixture of resin, fillers and/or fibers into a mold as opposed to building up layers through lamination. This technique produces different physical properties from laminating.
A high strength-reinforcing fiber used in lightweight structural composites. Produced by pyrolysis of an organic precursor fiber in an inert atmosphere at temperatures above 1800oF. Material can also be
graphitized by heat treating above 3000oF. See Graphic fiber.
Non-reinforced composite (resin used without reinforcing fibers). Combines polymers, fillers and additives as composites to meet specific applications requirements.
Technically considered an initiator, catalyst is the colloquial name given to the substance added to the resin or gel coat to initiate the cure. The most common catalyst used in the composites
industry are MEKP and BPO.
Plural components spray equipment that mixes catalyst and resin at the spray gun or applicator.
An elastic material used to protect joints or connections from external elements, particularly moisture.
The space between a male and female mold set in which the part is formed. Sometimes used to refer to a female mold.
A unit of measure used to describe the viscosity of a liquid. Viscosity is measured with a Brookfield Viscometer for most polyester resin applications.
A surface phenomenon indicating degradation of a cosmetic surface. Chalking is a powdery film that appears lighter than the original color.
CHOPPED STRAND MAT
A fiberglass reinforcement consisting of short strands of fiber arranged in a random pattern and held together with a binder. Mat is generally used in rolls consisting of ¾ oz/ft2
material to 2 oz/ft2 material.
A fiberglass reinforcement made by weaving strands of glass fiber yarns. Cloth is available in various weights measured in ounces per square yard or Kg/m2.
The ability of a surface coating or pigment to resist degradation due to environmental exposure.
A material made of distinct components. For example; a reinforcing fiber in a resin matrix where the combined properties are superior to the individual materials.
A closed mold, usually of steel, used to form a composite under heat and pressure.
A mechanical property description that measures the compression of a sample at a specified load. Described in ASTM D-695.
The stress a given material can withstand when compressed. Described in ASTM D-695.
Where two panels are attached to each other or a panel is attached to the building.
Refers to the use of a single or open mold onto which resin and reinforcement materials can be applied. Contact molding is characterized by one finished cosmetic side.
CONTINUOUS FILAMENT STRAND
A fiber bundle composed of many glass filaments. Also when referring to gun roving, a collection of string like glass fiber or yarn, which is fed through a chopper gun in the spray up process.
CONTINUOUS STRAND ROVING
A bundle of glass filaments which are fed through a chopper gun in the spray up process.
An automated process for forming panels and sheeting in which fabric or mat is passed through a resin bath, brought together between covering sheets, and passed through a heating zone for cure.
Squeeze rolls control thickness and resin content as the various plies are brought together.
A low-density material used between two FRP skins. Examples of core materials are end-grain balsa wood, urethane foam, PVC foam and various honeycomb materials.
Cracking of gel coat or resin due to stress.
The chemical bonding of molecules which in polymers occurs in the curing transition from a liquid to a solid.
The completion of the cross-linking process during which a composite develops its full strength.
An initiator or catalyst that initiates polymerization when added to a resin.
Time between introduction of catalyst or initiator to a polymer and final cure.