Definitions /Dictionary/Glossary - nptel

Variance: See Sample Variance.
Veil: An ultra thin mat similar to a surface mat, often composed of organic fibers as well as glass
fibers.
Viscosity: The property of resistance to flow exhibited within the body of a material.
Vinylester: A laminating resin which is processed much like polyester, but has cured properties
similar to some epoxy resins.
Void: Any pocket of enclosed gas or near-vacuum within a composite.
Void Content: The percentage of voids in a laminate.
Volatiles: Materials in a sizing or a resin formulation that can be vaporized at room or slightly
elevated temperature.
Volatile Organic Compounds (VOC): Carbon-containing chemical compounds (e.g., solvents
or liquids) that evaporate readily at ambient or process temperatures. Environmental, safety and
health regulations often limit exposure to these compounds, making low VOC content is
preferable.
Volatile Portions: Those portions vaporizing under specific conditions short of decomposition.
Non-volatiles remain.
Void Free: A laminate containing no entrapped air cavities, blisters, or voids.
Warp: The longitudinally oriented yarn in a woven fabric (see Fill); a group of yarns in long
lengths and approximately parallel.
Warpage: Dimensional distortion in a composite part.
Water Absorption: It is a ratio of weight of water absorbed by a material to the weight of dry
material. It is also called moisture content.
Water Jet: It is a high-pressure stream of water used for cutting organic composites.
Wax: A mold release agent.
Weave: The particular manner in which a fabric is formed by interlacing yarns, and usually
assigned a style number.
Weft: The yarns running perpendicular to the warp in a woven fabric; also called "woof".
Wet Flexural Strength (WFS): It is the flexural strength after water immersion; usually after
boiling the test specimen for two hours in water.