| advanced composite |
A composite made from specially formulated resins and high performance fibers. Advanced composites are used for applications that require a customized mixture of resins and reinforcements to produce specific properties in the composite. |
| autoclave |
A pressure vessel that promotes faster curing through a combination of vacuum and heat. |
| binder |
An ingredient used to bind together two or more other materials in a composite. Binders promote adhesion and cohesion. |
| bleeder |
The part of a vacuum bagging system that absorbs excess resin. |
| breather |
The part of a vacuum bagging system that allows air circulation throughout the assembly. |
| ceramic |
A hard, brittle material that can withstand high temperatures and resist corrosion. |
| chopped strand mat |
A sheet of material covered with discontinuous fiber reinforcements. |
| chopper gun |
The part of a spraying device that chops continuous strands of fiber so that they may be sprayed on to a surface. |
| composite |
A material that is made by combining a binding resin with small filaments of solid material. Composites have the strength of metal, the light weight of plastic, and the rigidity of ceramics. |
| compression stress |
The internal load that a part is subjected to when a force squeezes or pushes down on it. |
| continuous strand mat |
A sheet of material covered with long, continuous fiber reinforcements. |
| drape |
A measure of the suppleness of a fabric. A prepreg must have an adequate amount of drape in order to be shaped. |
| extrusion |
A molding process during which material is pushed or drawn through a die to create objects of a fixed cross-sectional profile. |
| fabric |
Material made by weaving fibers together. |
| fiber |
A reinforcing material whose length is greater than its height or width. Fibers are longer than whiskers or particles. |
| fiberglass |
Reinforcement material made from extremely fine strands of glass. Fiberglass is the most commonly used composite reinforcement. |
| fiberglass reinforced plastic |
FRP. A polymer that cannot be remelted or reformed once it has cured, due to a molecular process called cross-linking that occurs during curing. |
| filament |
A long, thin, hair-like material. Filaments are combined to form fibers. |
| flexural stress |
The internal load that a part is subjected to when a force causes an object to bend perpendicular to the object's long axis. |
| gel coat |
The protective outer coating of a composite material. |
| hand lay-up molding |
A manual molding process during which reinforcement in the form of a fabric or a mat is positioned manually into the mold and saturated with a resin. |
| initiator |
An ingredient used to facilitate chemical reactions. |
| injection molding |
A molding process during which resin is heated in a barrel and then injected into a mold by a reciprocating screw. The resin then cools in the mold and is ejected as a solid part. |
| lay-up molding |
A manual molding process during which reinforcement in the form of a fabric or a mat is positioned manually into the mold and saturated with a resin. |
| load |
The overall force applied to a material or structure. In a composite, the matrix transfers the load to the reinforcement fibers. |
| mat |
A sheet of material covered with fiber reinforcements. Reinforcements can be discontinuous (chopped) or continuous. |
| matrix |
The material that binds together the reinforcing fibers of a composite. The matrix is usually a viscous material that hardens to give shape to the composite part and to protect the fibers from damage. |
| metal |
A naturally occurring material with high electric and thermal conductivity, luster, density, and strength. Examples of metal include copper, iron, nickel, and lead. |
| mil gage |
A device used to measure the thickness of gel coat. |
| open molding |
A molding process during which fibers are placed into a single-sided or open mold. Resin is added to the fibers until they are fully wetted. The resin is then cured. |
| openness |
A measure of the open space between woven fibers in a fabric. |
| plastic |
A synthetic polymer that can be molded and hardened into a variety of shapes. |
| polyester |
A type of thermoset that is commonly combined with other polymers for numerous commercial uses. Polyester is light, strong, and resistant to weather and corrosion. |
| polypropylene |
A type of thermoplastic known for being very lightweight. |
| polyvinyl alcohol |
A water-soluble synthetic polymer used as a release material in open molds. Polyvinyl alcohol has excellent film forming, emulsifying, and adhesive properties and is resistant to oil, grease, and solvent. |
| pre-impregnated fiber |
A ready-to-mold sheet of fiber reinforcement that has been preimpregnated with resin. Also known as a prepreg. |
| prepreg |
A ready-to-mold sheet of fiber reinforcement that has been preimpregnated with resin. Also known as pre-impregnated fiber. |
| reinforcement |
The part of the composite that provides strength, stiffness, and the ability to carry a load. In manufacturing, fibers are the most commonly used reinforcement. |
| release material |
A substance that is applied to a mold surface to make it easier to release a molded part. |
| resin |
A substance made from either synthetic or natural polymers and used for composite matrices. In essence, a resin is a polymer that has not been processed into its final form. |
| sealant |
The part of a vacuum bagging system that adheres to the vacuum bag and creates an airtight assembly. |
| shear stress |
The internal force that causes a material to slide against itself or its internal components. |
| spray-up molding |
A manual molding process during which an operator uses a spray machine to simultaneously apply resin and chopped fiberglass strands to a mold. |
| strength-to-weight ratio |
The relationship between a material's strength and its weight. To find the ratio, the strength of a material is divided by its density. |
| tensile stress |
The internal load that a part is subjected to when pulled apart by an applied force. |
| thermoforming |
A plastic shaping process that shapes heated plastic sheets around a mold. Thermoforming is a lower-volume process that produces detailed parts with close tolerances. |
| thermoplastic |
A polymer in which the molecules are not cross-linked, or they are cross-linked to a weaker degree. A thermoplastic polymer can be reshaped or reformed by reheating the polymer. |
| thermoset |
A polymer that cannot be remelted or reformed once it has cured, due to a molecular process called cross-linking that occurs during curing. |
| traditional composite |
A composite that uses a relatively consistent combination of resin and fiberglass reinforcement. Traditional composites are low-cost and are processed by traditional methods. |
| vacuum bag |
The part of a vacuum bagging system that forms an airtight seal over an entire assembly. |
| vacuum bagging |
A type of compression molding during which a bag is placed over the mold and the vacuum compresses the bag and squeezes out any air or excess resin. |
| veil |
A thin fiberglass fabric made of very fine strands. Veil is used to cover any exposed fiberglass strands on the composite and create a smoother surface. |
| vinyl ester |
A type of polymer used in engineering composite resins. Vinyl esters have mechanical properties that are between those of polyesters and epoxies. |
| wetting |
Applying a liquid to a solid surface. In composites, wetting allows the matrix to bond with the reinforcement. |
| woven roving |
A thick, heavy fiberglass fabric made by loosely weaving large strands of fiber. |