Definitions /Dictionary/Glossary - nptel
Definitions /Dictionary/Glossary - nptel
Definitions /Dictionary/Glossary - nptel
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
and removed by the vacuum. The part is cured with temperature, pressure and time. It is also<br />
called bag molding.<br />
Vacuum Molding: Low cost entry method into RTM which uses a rigid cavity mold half and a<br />
semi-rigid upper mold half, both made of FRP. Capable of producing 3-4 times as many<br />
moldings as that produced through open mold, with acceptable repeatability (but not equal to that<br />
of RTM.)<br />
Veil: Ultra thin mat similar to a surface mat.<br />
Vinyl-Coated Glass Yarn: Continuous glass filament yarn coated with pigment and plasticized<br />
vinyl chloride resin.<br />
Vinyl Esters: Thermosetting resins containing esters of acrylic and/or methacrylic acids, many<br />
of which have been made from epoxy resin. Cure is accomplished as with unsaturated polyesters<br />
by CO-polymerization with other vinyl monomers, such as styrene.<br />
Viscosity: Measure of a liquid’s resistance to flow.<br />
Void Content: The percentage of voids in a laminate.<br />
VM: See Vacuum Molding.<br />
Warp: Yarn running lengthwise in a woven fabric. A group of yarns in long lengths and<br />
approximately parallel, put on beams or warp reels for further textile processing including<br />
weaving, knitting, twisting, dyeing, etc.<br />
Warp Size: Chemicals applied to the warp yarn to improve strand integrity, strength and<br />
smoothness in order to withstand rigors of weaving.<br />
Weave: Particular manner in which a fabric is formed by interlacing yarns; usually assigned a<br />
style number.<br />
Weft: The system of yarns running crosswise in a fabric. It is also known as fill.<br />
Wet Flexural Strength (WFS): It is the flexural strength after water immersion, usually after<br />
boiling the test specimen for two hours in water.<br />
Wet Lay-Up: Reinforced plastic with liquid resin applied after the reinforcement is laid up. It is<br />
opposite of "dry lay-up", "prepreg".<br />
Wet-Out Rate: Time required for a plastic to fill the interstices of a reinforcement material and<br />
wet the surface of the reinforcement fibers; usually determined by optical or light transmission<br />
means.