Industry Glossary - D

The decay with time of the amplitude of free vibrations of a specimen.

Diallyl Phthalate (Thermoset Resin).

The distance, in the open position, between the moving and fixed tables or the platens of a hydraulic press. In the case of a multi-platen press, daylight is the distance between adjacent platens. Daylight provides space for removal of the molded part from the mold.

A finishing technique used to remove the excess, unwanted material (flashing) on a plastic molding.

Separation of composite layers, either local or covering a wide area. Can occur in the cure or subsequent life.

A nonconductor of electricity. The ability of a material to resist the flow of an electrical current.

The ratio of the capacitance of an assembly of two electrodes separated solely by a plastic insulating material to its capacitance when the electrodes are separated by air.

The heating of materials by dielectric loss in a high-frequency electrostatic field.

This is an electrical property and gives an indication of how well the material acts as an electrical insulator. It describes how much of an electrical voltage can be built up on one side of the material before it is communicated to the other side. Units – Volts per mil of thickness (volts/mil). Higher numbers indicate materials which are better insulators. C means that the material conducts electricity and therefore has no dielectric strength.

Ability of a plastic part to retain the precise shape to which it was molded, cast, or otherwise fabricated.

Specially formulated sizings on textile yarns that allow them to be resin compatible.

The degree to which the roving separates into discrete bundles after being chopped. Good dispersion is characterized by a bed of bundles which are uniform in width. Poor dispersion is characterized by a wide distribution in the widths of various bundles in the bed. Poor dispersion can cause poor wet-through and wet-out.

Change in shape from that which is intended. Symptomatic of laminating difficulties, curing problems, tooling problems or resin shrinkage.

A straight piece of material used to spread resin, as in application of a thin film of resin for use in hot melt prepreg or for use as an adhesive film. Also called paste metering blade.

The failure of the roving doff to maintain its shape and stability during run-out or storage. Doff collapse generally occurs when there is only a 1/2″ to 1/4″ ring of roving left from the original doff.

The taper or slope of the vertical surfaces of a which allow removal of molded parts.

Height of the bed of chopped fibers.

A pause in the application of pressure or temperature to a mold, made just before it is completely closed, to allow the escape of gas from the molding material.