Buckling - A mode of failure characterized generally by an unstable lateral deflection due to compressive action on the structural element involved. This mode often occurs in glass reinforced thermosets due to resin shrinkage during cure. In advanced composites, buckling may take the form not only of conventional, general instability and local instability but also a microinstability of individual fibers.

Calcium Carbonate - CaCO3, one of the most stable, common, AND widely dispersed materials. It occurs in oyster shells, chalk, limestone, marble and travertine, and is a major cause of boiler scale when hard water is used in heating systems.

Carbon Fiber - Reinforcing fiber produced by the pyrolysis of an organic precursor fiber, such as PAN, rayon or pitch, in an inert environment at temperatures above 1,800°F. Carbon fibers are typically carbonized at about 2,400°F and contain 93 percent to 95 percent carbon. Carbon fibers are known for their light weight, high strength and high stiffness.

Creep - A permanent inelastic deformation in a material due to changes in the material caused by the prolonged application of structural stress.

E-Glass - Borosilicate glass, or electrical glass, is the most common fiber in composite construction. E-glass is cheaper, but weaker than S-glass.

Flexural Modulus - The ratio, within the elastic limit, of the applied stress on a test specimen in flexure to the corresponding strain in the outermost fibers of the specimen.

Flexural Strength - The property of a material or a structural member that indicates its ability to resist failure in bending.  A unit of resistance to the maximum load before failure by bending.

Kevlar - DuPont’s trade name for poly-para-phenylene terephthalamide, a strong, tough, stiff, high melting point fiber, used in composite construction. Lighter, stiffer, more expensive than glass fiber.

Pot Life - How long a catalyzed thermosetting resin retains a viscosity low enough to be workable.

S-Glass - Magnesia/alumina/silicate glass reinforcement fiber designed to provide very high tensile strength. Used in high-performance composites.

Styrene - An unsaturated hydrocarbon used in plastics. It is a colorless, toxic liquid with a strong aromatic aroma. In polyester resin it serves as a solvent and as a co-reactant in the polymerization process that occurs during curing.

Tensile Modulus - When a bar is pulled in tension, it has to get longer. The tensile modulus is used to calculate how much longer it will get when a certain load is applied to it. Units are normally millions of pounds per square inch. Higher numbers indicate materials which will not elongate as much as others when they are being compared under equal tensile loading conditions.

Tensile Strength - The breaking strength of a material when subjected to a tensile (stretching) force. Usually measured by placing a standard piece in the jaws of a tensile machine gradually separating the jaws and measuring the stretching force necessary to break the test piece. Tensile strength is commonly expressed as pounds per square inch of original cross sectional area.

Thixotropic - Substance that is gel-like at rest, but fluid when agitated, and thus can be applied easily but clings to a vertical surface. Thixotropic substances have high static shear strength and low dynamic shear strength at the same time, and lose viscosity under stress.