Air-inhibited Resin- A resin in which surface cure will be inhibited or stopped by the presence of air.
"B" Stage (of Resin)- The condition of a partially cured resin polymer when it is only partially soluble in monomer or acetone but still plastic and still heat fusible.
Colour Pigments- Ground colouring materials supported in a thick liquid. Added to the resin, they give it colour
Crazing- Hairline cracks either within or on the surface of a laminate, caused by stresses generated during cure, removal from a mould, impact or flexing.
Crosslinking– Chain-reaction polymerization which results in chemical links (bonds) between individual polymer chains. This occurs in all thermosetting resins. Styrene monomer and methyl methacrylate monomer are the most common crosslinking agents used in polyester resins.
Cure- The total crosslinking or polymerization of resin molecules which permanently alters the properties of the resin changing it from a liquid to a solid.
Cure Time- The time required for the liquid resin to reach a cured or fully polymerized state after the catalyst has been added.
Delamination- Failure of internal bending between layers of the laminate.
Dimensional Stability- Ability to retain constant shape and size under various environmental conditions, such as temperature and humidity.
End- As applied to fibrous reinforcements, a bundle of essentially parallel (i.e., entwined) fibers, usually glass.
Exotherm Curve- A graph of temperature plotted against time during the curing cycle. Peak exotherm is the highest temperature reached during the curing reaction.
Exothermic Heat- Heat given off during a polymerization reaction by the chemical ingredients as they react and the resin cures.
FBVF(Fiberglass Backed Vacuum Forming)- Combining a thermoformed thermoplastic sheet with a fiberglass mat or roving using the spray-up or hand lay-up process.
Filament- A single, hair-like fiber of glass characterized by extreme length, which permits its use in yarn with little or no twist and usually without the required spinning operation.
Fill or Sanding Resin- A general purpose polyester resin used to soak and fill reinforcing material in the initial lay-up of a surfacing application; usually contains wax.
Fillers- Any one of a number of inexpensive substances which are added to plastic resins to extend volume, improve properties and lower the cost of the article being produced. Examples are calcium carbonate, alumina trihydrate, feldspar, and calcium sulfate.
Fire Retardancy– Reduction in the ability of a plastic to ignite and burn. This is accomplished by using compounds (resins or additives) that contain halogens (bromine or chlorine) or phosphorous. Usually alumina trihydrate filler is also used because of its ability to release water when exposed to high heat.
Foams, Urethane- Polyurethane resins are produced by reacting diisocyanates with polyols to form polymers having free isocyanate groups. These groups, under the influence of heat or certain catalysts, will react with each other, or with water, glycols, etc., to form a foam.
Foams, Flexible– A thermoplastic urethane foam which is adaptable and often used for cushioning in the furniture and automotive industries.
Foams, Rigid- A thermoset urethane foam which has a higher density, higher modulus, and harder surface than flexible urethane foams.
Gel- A partial cure of plastic resins; a semi-solid, jelly-like state similar to gelatin in consistency.
Gel Time- Time required to change a flowable liquid resin into a non-flowing gel.
HDPE(High Density Polyethylene)- A thermoplastic material composed of polymers of ethylene. It has relatively high rigidity and can be modified, e.g. with isoprene, to have high impact strength.
Inhibitor- A substance that retards polymerization, thus extending the shelf life of polymers and monomers. Also used to extend the gel time and cure time of a thermoset resin.
Laminate- A material composed of successive layers of resin and fiberglass bonded together.
Lamination- The compilation of layers of glass matte and resin, and eventual bonding of these layers together.
Monomer- A single molecule capable of polymerizing.
Non-Air-Inhibited Resin- A polyester resin using phthalic anhydride as the starting point. A surfacing agent is added to exclude air from the surface of the resin.
PE (Polyethylene)- A thermoplastic material composed of polymers from ethylene. It is normally a translucent, tough, waxy solid which is unaffected by water or by a large range of chemicals.
PVC (Polyvinyl Chloride)- A thermoplastic material composed of copolymers of vinyl chloride. A colourless solid resistant to water, concentrated acids and alkalis.
Polymer- The end product, usually a solid, produced from monomers.
Porosity- The formation of undesirable clusters of air bubbles in the surface or body of the laminate.
Pot Life- The length of time that a catalyzed resin remains workable.
Preform Fiber- Glass formed over a screen shaped like the mould in which the preform will be used. It eliminates the need for over-lapping or mitering the corners in molding. Used primarily to form deep draws or complex parts.
Prepreg- Glass roving or cloth loaded with B-stage resin, catalyst, and pigment ready for placement in a mould.
Promoter- See accelerator .
Release Agent- A lubricant, often wax, to prevent the adhesion of the moulded part to the mould. An internal lubricant such as zinc stearate is used in high temperature moulding to obtain release where wax would melt or be absorbed.
Resin- A liquid plastic substance used as a matrix for glass fibers. It is cured by crosslinking.
Thermoset- A plastic material that will undergo or has undergone a chemical reaction caused by heat, catalyst, ultraviolet light, etc., leading to the formation of a solid. Once it becomes a solid, it cannot be reformed.
Thermoplastic- A plastic material that can be readily softened and reformed by heating and be re-hardened by cooling.
Sizing- The treatment applied to the glass fiber to allow the plastic resins to flow freely around and bond to them.
Shelf Life- The length of time a non-catalyzed resin maintains specified working properties while stored in a tightly sealed opaque container.
Staple Fiber- A glass fiber of short length formed by blowing molten glass through holes.
Substrate- Any material which provides a support surface for other materials.
Tack- The stickiness of an adhesive measurable as the force required to separate an adherent from it by viscous or plastic flow of the adhesion.
Thickeners- Material added to the resin to thicken it so that it will not flow as readily.
Thixotropic- The property of becoming a gel at rest, but liquifying again on agitation.
Viscosity- A measure of the resistance of liquid to flow.
Wet-out- The ability of aresin to saturate fiberglass reinforcement.
Yarn- A twisted strand or strands of glass fibers which can be woven, braided, served, and processed.