Industry Glossary - C

Glass with a soda-lime-borosilicate composition that is used for its chemical stability in corrosive environments.

The final stage in the reaction of certain thermosetting resins in which the material is practically insoluble and infusible.

Yarn that is plied more than once; yarn made by plying two or more previously plied yarns.

Element that provides the backbone for all organic polymers. Graphite is a more ordered form of carbon. Diamond is the densest crystalline form of carbon.

Composite material consisting of carbon or graphite fibers in a carbon or graphite matrix.

Fiber produced by the pyrolysis of organic precursor fibers, such as rayon, polyacrylonitrile (PAN), and pitch, in an inert environment.

The process of untangling and partially straightening fibers by passing them between two closely spaced surfaces which are moving at different speeds, and at least one of which is covered with sharp points, thus converting a tangled mass of fibers to a filmy web.

Process of pouring a mixture of resin, fillers and/or fibers into a mold as opposed to building up layers through lamination. This technique produces different physical properties from laminating.

A substance which markedly speeds up the cure of a compound by decomposing in the presence of a promoter to release an active oxygen radical. Catalyst content can vary from 0.2% to 2.0% with higher catalyst levels giving faster gel times. Examples are methyl ethyl ketone peroxide, benzoyl peroxide.

Totally unpredictable failures of a mechanical, thermal, or electrical nature.

A consolidated group of individual strands which, when checked between two fixed points of length, exhibit strands of different lengths. The resulting curve between fixed points of the inextensionable material is defined as catenary. The amount of catenary is measured by the distance between the topmost and lowermost strands when stretched between two fixed points.

Smooth metal plates, free of surface defects, the same size and shape as a composite lay-up, used immediately in contact with the lay-up during the curing process to transmit normal pressure and temperature, and to provide a smooth surface on the finished laminate.

Space inside a mold in which a resin or molding compound is poured or injected. The female portion of the mold. That portion of the mold that encloses the molded article (often referred to as the die). Depending on the number of such depressions, molds are designated as a single cavity or multiple cavity.

The vertical plane of doffs on a pallet. A pallet may be constructed for 4- or 12-end run-out depending on application.

Surface phenomenon indicating degradation of a cosmetic surface. Chalking is a powdery film which appears lighter than the original color.

A surface finish applied to the fiber that contains some chemical constituents other than water.

The ease of chopping/cutting the glass fibers to a uniform length.

In injection molding and transfer molding, the pressure that is applied to the mold to keep it closed in opposition to the fluid pressure of the compressed molding material.

Fiberglass reinforcement made by weaving strands of glass fiber yarns.

A group of chopped bundles of glass fibers which has collected on the SMC machine and then fallen into the bed of glass. The clump produces areas of high glass content which may not wet-through.

How much a material shape will change for each degree of temperature change.

The distortion that takes place in materials under continuous load at temperatures within the working rage of the material without a phase or chemical change.

A spool on which the gathered strands from the bushing are wound for further processing.

The application of a temporary vacuum bag and vacuum to remove trapped air and compact the lay-up; also in SMC machines for removal of air prior to roll-up.

The ability of two or more substances combined with one another to form a homogeneous composition of useful plastic properties; for example, the suitability of a sizing or finish for use with certain general resin types.

Chemical or mechanical bonding of dissimilar materials such as glass fiber and polyester resin, whose cumulative properties are superior to the individual materials.

A combination of two or more materials (reinforcing elements, fillers, and composite matrix binder). The constituents retain their identities; that is, they do not dissolve or merge completely into one another although they act in concert. Normally, the components can be physically identified and exhibit an interface between one another.

Manufacturer who mixes a polymer, fillers, additives and glass fibers, and sells the resulting pellets for injection molding.

A process where a mold is open when the material is introduced and shapes the material by the pressure of closing and by heat.

Ratio of compressive stress to compressive strain below the proportional limit. Theoretically equal to Young’s modulus determined from tensile experiments.

This number describes how much of a nonmoving load a bar can take before it is crushed. Units are normally thousands of pounds per square inch. (103 psi) – Mega Pascals (mPa). Higher numbers indicate stronger materials which can withstand a heavier load before they break.

A chemical reaction in which two or more molecules combine, with the separation of water or some other simple substance.

Reciprocal of volume resistivity. The electrical or thermal conductance of a unit cube of any material (conductivity per unit volume).

Ability of the mat to conform to difficult shapes without causing wrinkles or leaving excessively resin-rich or glass-rich radii, which may craze.

Refers to the use of a single or open mold onto which layers of polymer and reinforcement materials can be applied. Contact molding is characterized by one finished cosmetic side. Cure is either at room temperature using a catalyst-promoter system or by heating in an oven, without additional pressure.

Filaments that extend substantially throughout the length of the yarn.

This is the maximum temperature the material should be subjected to in a continuous application. Below this temperature the material is acceptable. Above this temperature the material may decompose, melt, or otherwise fail in an application. Units – degrees Fahrenheit (�F)- degrees Centigrade (�C). Higher numbers mean that the material can be used continuously at higher temperatures.

Process for forming panels and sheeting in which fabric or mat is passed through a resin bath, brought together between covering sheets, and passed through a heating zone for cure. Squeeze rolls control thickness and resin content as the various plies are brought together.

Rovings supplies in a package that allows for continuous processing.

Fiberglass mat of very long individual fibers with a regular crossed pattern loosely held together with a binder.

A resin produced by copolymerization, the process where unlike molecules are arranged in alternate sequence in a chain.

A low-density material used between two FRP skins. Examples of core materials are end-grain balsa wood, urethane foam, PVC foam and various honeycomb materials. The central member, usually foam or honeycomb, of a sandwich construction to which the faces of the sandwich are attached or bonded. The central member of a plywood assembly. A channel in a mold for circulation of heat transfer media. A device on which prepreg is wound.

Continuous heat cleaning and weave setting.

The ability of a material to withstand contact with ambient natural factors or those of a particular artificially created atmosphere, without degradation or change in properties. For metals, this could be pitting or rusting; for or organic materials, it could be crazing.

Any chemical substance designed to react with both the reinforcement and matrix phases of a composite material to form or promote a stronger bond at the interface.

Cracking of gel coat or resin due to stress. Region of ultra-fine cracks, which may extend in a network on or under the surface of a resin or plastic material. May appear as a white band. Often found in a filament-wound pressure vessel or bottle.

Glass Fiber Manufacturing – A framework used to hold forming cakes so they can be wound or roved into roving doffs. Creels generally hold 10 to 33 forming cakes which are replaced randomly as they run out as doffs are roved. Composite Fabrication – The area where the pallets of roving are placed and “threaded up” through metal tubes or guide eyes to a chopper.

The slow movement of a plastic material with time.

Rate of the slope of the creep-time curve at a given time. Deflection with time under a given static load.

The setting up of chemical links between molecule chains. This occurs in all thermosetting resins. Styrene monomer is a crosslinking agent in polyester resins.

The crosslinking or total polymerization of the molecules of the resin which alters the properties of the material and changes it from a liquid into a solid.

The time/temperature/pressure cycle used to cure a thermosetting resin system or prepreg

The time required for the liquid resin to reach a cured or fully polymerized state after the catalyst has been added.

A catalytic or reactive agent that, when added to a resin, causes polymerization. Also called hardener.

Severed ends on the doff which generally are caused by abrasion during shipping or by careless use of a knife when the package is removed from the pallet.