Industry Glossary - S

A family of magnesium-alumina-silicate glasses with a certified chemical composition which conforms to an applicable material specification and which produces high mechanical strength.

Styrene Acrylonitrile (Thermoplastic Resin).

Panels composed of a lightweight core material, such as honeycomb or foamed plastic, to which two relatively thin, dense, high-strength or high-stiffness faces or skins are adhered.

A light, woven or non-woven fabric with relatively large openings between the yarns, used as reinforcement for paper and other products.

A flanged cylinder onto which yarn is drawn and accumulated from yarn bobbins or packages.

Wrapping of yarn around a product in one or more layers, to form a protective covering.

A flexible, small diameter yarn or strand, usually treated with a surface coating, lubricant, or both, intended to be used to stitch one or more pieces of material or an object to a material.

Engineering term referring to forces applied normal to the surface of a given material. The movement between plies of a laminate is referred to as interlaminate shear.

Composite of fibers, usually a polyester resin, and pigments, fillers, and other additives that have been compounded and processed into sheet form to facilitate handling in the molding operation.

Allowable storage time before a product must be used.

The simplest strand of textile material suitable for operations such as weaving, knitting, etc.

The treatment applied to the glass fiber to allow the resin and glass to adhere to one another. Also allows glass fiber to be conveniently handled.

A loose coil of roving or strands which is generally used as a Quality Control sample.

First layer of laminate next to the gel coat.

The method of applying size to a width of warp yarns on a continuous basis.

Glass bundles which are thrown off the chopper or cot during the chopping operation.

A term used to describe the geometry of a fibrous glass reinforcement in the forming operation, e.g., 2K37 S/2 meaning a configuration in forming which makes a nominal fiber diameter in the “K” range which is 3700 yards to a pound and is split into two discrete bundles in the forming cake.

A roving product whose sizing is moderately soluble in acetone or styrene which results in the tendency of the bundles to open readily or filamentize the matrix resin. The size is generally between 50% and 80% soluble in acetone.

The amount of sizing on the glass expressed as a percentage of the total weight.

This describes the weight of a material in relation to the weight of an equal volume of water. For example, a material with a Specific Gravity of 2.0 weighs twice as much as an equal volume of water. Units – Because specific gravity is a ratio of values for two materials, there are no units. Higher numbers indicate heavier materials.

(Thermal Capacity) – This defines how much heat is needed to raise the temperature of one pound of material one degree Fahrenheit. Units – BTUs per pound per degree Fahrenheit (BTA/LB/�F) – Joules/Kilogram Kelvin (J/KgK). Higher numbers means that it takes more input heat energy to raise the temperature of a material.

The joining of two ends of yarn by intertwining, knotting, overlapping or adhering them together.

One bundle.

A ratio of the actual number of ends divided by the theoretical number of ends in a roving doff. Expressed as a percentage.

Technique in which a spray gun is used as an applicator tool. In reinforced plastics, for example, fibrous glass and resin can be simultaneously deposited in a mold.

Connector between the runner and the nozzle in the injection molding machine.

Filaments produced in short lengths from the bushing (usually less than 17 inches), to be gathered into strands or sliver.

The buildup of an electrical charge which causes the chopper roving to “cling” or stick to the chopper, line and/or people. The static level is quantified by measuring the electrical field strength in kilovolts per inch.

In the roving process or shop – a primary group of bundles gathered together in a creel. A strand is that which is pulled out of a doff. A plurality of drawn and elongated individual filaments combined together to form an individual strand. Strands are held together and protected by the sizing.

U.S. Yardage System: the length, in hundreds of yards, of a single strand having a mass of one pound. European TEX System: the mass, in grams, of a strand 1000 meters in length.

Relating to the ability of the size to keep all the filaments of a bundle stuck together during chopping. Good strand integrity is required for good flow in or wet-through and wet-out on the mold.

Evolution of two other plastic molding processes-RIM and RTM. S-RIM uses the fast polymerization reactions of RIM-type polymers, its intensive resin mixing procedures, and its rapid resin injection rates. S-RIM also employs preforms like RTM to obtain composite mechanical properties.

A water-thin liquid monomer used to thin polyester resins and act as the crosslinking agent.

Very thin mat, usually 180 to 510 mm (7 to 20 mil) thick, used primarily to produce a smooth, resin-rich surface on a reinforced plastic laminate, or for precise machining or grinding.

Chemicals used to modify or change the surface of a layer of resin or polymer. Usually used to form a film on a curing resin, producing a tack-free surface.