Definitions /Dictionary/Glossary - nptel

Soft Glass: A roving product whose sizing is moderately soluble in acetone or styrene, resulting
in bundles that tend to open readily or filamentize the matrix resin. The size is generally between
50% and 80% soluble in acetone.
Solid: The amount of sizing on glass expressed as a percentage of the total weight.
Solvent Resistance: The non-swelling of a material; also, a material’s ability to resist being
dissolved by a particular solvent.
Specific Gravity: A material’s weight 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. Because specific gravity is a ratio of values for two materials, there are no units. Higher
numbers indicate heavier materials.
Specific Heat (Thermal Capacity): The amount of heat needed to raise the temperature of one
pound of material one degree Fahrenheit (F). Units are measured in BTUs per pound per degree
(BTA/LB/°F) - Joules/Kilogram Kelvin (J/KgK). Higher numbers indicate more input heat
energy is needed to raise the temperature of a material.
Specimen: An individual piece or portion of a sample used for a specific test; also, of specific
shape and dimensions.
Splice: Joining two ends of yarn by intertwining, knotting, overlapping or adhering them
together.
Split: One bundle.
Split Mold: A mold whose cavity is formed of two or more components held together by an
outer chase. The components are known as splits.
Spray-Up: 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.
Sprue: Connector between the runner and nozzle in an injection-molding machine.
Splitting Efficiency: Ratio of the actual number of ends divided by the theoretical number of
ends in a roving doff, expressed as a percentage.
Staple: Filaments produced in short lengths from the bushing (usually less than 17 inches)
gathered into strands or sliver. See Continuous Filament
Starved Area: It is a portion of a plastic part without sufficient resin to completely wet out the
reinforcement. It is usually due to improper wetting, impregnation or excessive molding
pressure.