IGNITION LOSS
The difference in weight before and after burning; as with glass, the burning off of the binder or size.

IMPACT STRENGTH
The ability of a material to withstand shock loading; the work done in fracturing a test specimen in a specified manner under shock loading.

IMPREGNATE
In reinforced plastics, the saturation of the reinforcement with a resin.

IMPREGNATED FABRIC
See Prepreg.

INCLUSION
A physical and mechanical discontinuity occurring within a material or part, usually consisting of solid, encapsulated foreign material. Inclusions are often capable of transmitting some structural stresses and energy fields, but in a noticeably different manner from the parent material.

INHIBITOR
A substance which retards a chemical reaction; used in certain types of monomers and resins to prolong storage life.

INSERT
An integral part of a plastics molding consisting of metal or other material which may be molded into position or pressed into the molding after the molding is completed.

INSTRON
An instrument utilized to determine the tensile and compressive properties of materials.

INTEGRAL COMPOSITE STRUCTURE
Composite structure in which several structural elements, which would conventionally be assembled by bonding or with mechanical fasteners after separate fabrication, are instead laid up and cured as a single, complex, continuous structure: e.g., spars, ribs, and one stiffened cover of a wing box fabricated as a single integral part. The term is sometimes applied more loosely to any composite structure not assembled by mechanical fasteners.

INTEGRAL HEATING
A system in which heating elements are built into a tool, forming part of the tool and usually eliminating the need for an oven or autoclave as a heat source.

INTERFACE
The junction point or surface between two different media; on glass fibers, the contact area between glass and sizing or finish; in a laminate, the contact area between the reinforcement and the laminating resin.

INTRALAMINAR
Descriptive term pertaining to some object (e.g., voids), event (e.g., fracture), or potential field (e.g., temperature gradient) existing entirely within a single, lamina without reference to any adjacent laminae.

INTERLAMINAR SHEAR
The shearing force tending to produce displacement between two laminae along the plane of their interface; usually the weakest element of a composite.

INTERLAMINAR SHEAR STRENGTH
The maximum shear stress existing between layers of a laminated material.

INTUMESCENT
A fire-retardant technology which causes an otherwise flammable material to foam, forming an insulating barrier when exposed to heat.

IN-SITU
In the position which it will finally occupy, e.g. molding or forming foam.

ISO
Abbreviated terminology for the isophthalic acid type resins and gel coats.

ISOTROPIC
Having uniform properties in all directions-independent of the direction of load application.

ISOPHTHALIC
A polyester resin based on isophthalic acid, generally higher in properties that a general purpose or orthothatic polyester resin.

IZOD IMPACT TEST
A destructive test designed to determine the resistance of a plastic to the impact of a suddenly applied force.

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Glossary Section (I) Last Updated: 9/3/99 1:02 PM

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