QUASI-ISOTROPIC
Approximating isotropy by orientation of piles in several directions.

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RAMPING
A gradual, programmed increase/decrease in temperature or pressure to control the cure or cooling of composite parts.

RATE TOOLS
Tools designed to be used repeatedly in a production

REINFORCED MOLDING COMPOUND
Compound supplied by raw material producer in the form of ready-to-use material, as distinguished from premix.

REINFORCED PLASTIC
A plastic with relatively high stiffness or very high strength fibers embedded in the composition. This improves some mechanical properties over that of the base resin.

REINFORCEMENT
A strong inert material bonded into a plastic to improve its strength, stiffness, and impact resistance. Reinforcements are usually long fibers of glass, asbestos, sisal, cotton, etc., in woven or nonwoven form. To be effective, the reinforcing material must form a strong adhesive bond with the resin. ("Reinforcement" should not be used synonymously with "filler").

REINFORCING CORD
Loosely twisted cord made up from rovings and designed for incorporation in moldings where edge reinforcement and high strength ribs are necessary.

RELEASE AGENT
A material which is applied in a thin film to the surface of a mold to keep the resin from bonding to the mold.

RELEASE FILM
An impermeable film layer that does not bond to the composite during cure.

RESILIENCE
A property of a material which is able to do work against restraining forces during return from a deformed condition.

RESIN
A solid, semisolid, or pseudo solid organic material which has an indefinite and often high molecular weight, exhibits a tendency to flow when subjected to stress, usually has a softening or melting range, and usually fractures conchoidally. In reinforced plastics, the material used to bind together the reinforcement material; the "matrix."

RESIN CONTENT
The amount of resin in a laminate expressed as either a percent of total weight or total volume.

RESIN SYSTEM
A mixture of resin, with ingredients such as catalyst, initiator, diluents, etc. required for the intended processing and final product.

RESIN-RICH AREA
Space which is filled with resin and lacking reinforcing material.

RESIN-STARVED
Areas of insufficient resin, usually identified by low gloss, dry spots or fiber show.

RESIN TEARING
Separation of pigments from the polyester, usually seen as black wavy lines.

RESIN TRANSFER MOLDING (RTM)
A molding process in which catalyzed resin is transferred into an enclosed mold into which the fiber reinforcement has been placed; cure normally is accomplished without external heat. RTM combines relatively low tooling and equipment costs with the ability to mold large structural parts.

RESIN VISCOSITY
Viscous property of a resin system or solid to liquid transition resistance to flow, which can be altered by temperature and pressure as necessary to achieve desired flow characteristics.

REVERSE IMPACT TEST
In which one side of a sheet of material is struck by a pendulum or falling object and the reverse side is inspected for damage.

REVERSE SANDWICH LAY-UP
A laminate arrangement in which the reinforced mat is laminated between outer layers of other materials.

RIB
A reinforcing member of a fabricated or molded part.

RIBBON DIRECTION
On a honeycomb core, the way the honeycomb can be separated. The direction of one continuous ribbon.

ROLL-OUT
A process used in spray-up and hand lay-up procedures where the resin and glass reinforcement are compacted to a uniform laminate with rollers.

ROOM TEMPERATURE CURING ADHESIVES
Adhesives that set (to handling strength) within an hour at temperatures from 68 to 86 F, and later reach full strength without heating.

ROVING (filament winding)
The term roving is used to designate a collection of bundles of continuous filaments either as untwisted strands or as twisted yarns. Roving may be lightly twisted, but for filament winding they are generally wound as bands or tapes with as little twist as possible. Glass rovings are predominantly used in filament winding.

ROVING BALL
A term used to describe the supply package offered to the winder. It consists of a number of ends or strands wound to a given outside diameter onto a length of cardboard tube.

RP
Reinforced plastic, polymer, or polyester.

RTA (Room Temperature Ambient)
An environmental condition 73(5( (23(3(C) at ambient laboratory relative humidity; 2) a material condition where, immediately following consolidation/cure, the material is stored at 73(5( (23(3(C) and at a maximum relative humidity of 60%.

RTP
Sometimes used to distinguish reinforced thermoplastic from reinforced thermosetting plastic.

RUBBER PLUNGER MOLDING
A variation of the matched-die molding process which uses a heated metal female mold (or outer half) and a rubber plunger male mold. Applicable for relatively small molds with modest undercuts where low pressures are involved.

RULE-OF-MIXTURES
When combined, the properties of the composite material is some combination of the properties of the two constituent materials. The composite property equals the amount of the fiber property multiplied by the volume percentage of fiber, plus the amount of matrix property multiplied by the volume percentage of the matrix.

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Glossary Section (Q, R) Last Updated: 4/27/99 10:18 AM

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