A
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VINYL: See "Polyvinylchloride/PVC".
VISCOSITY: The resistance of a fluid to flow. A measurement
of this property provides useful information with respect to the
coatability of a material.
VOID: An area on the mass side of the tape which has no
mass on it.
VOLATILITY: Common terminology referring to the residual
solvent content in various coated materials or raw materials.
VULCANIZATION: See "Heat
Curing".
WALL MIXER: A slow drum mixer usually consisting of a single
shaft with one or several paddles. Used primarily to mix small
batches or to remix material in drums that have become stiff,
separated, or gelled.
WATER VAPOR TRANSMISSION RATE: A test by which the weight
of water vapor transmission through a tape is measured in grams
per hundred square inches per 24 hours. It is a measure of the
moisture barrier properties of a tape.
WATER ABSORPTION: The degree to which a tape will soak
up and hold water.
WATER PENETRATION: The measure of a tape's ability to prevent
the passage of water through the tape itself.
WEB: A term synonymous with backing or substrate.
WETTING: The ability of an adhesive to flow and come into
intimate contact with the surfaces to which it is applied.
WIND-UP: The equipment located at the exit end of the coater
which winds the coated tape onto a bundle roll.
WOVEN: A textile fabric formed by interlacing cross yarns
(fill) with continuous machine direction yarns (warp). A "Non-woven",
on the other hand, is a fabric-like material made from fibers
that are laid down randomly in a process similar to paper making,
and the fibers are bonded together with a binder and/or heat and
pressure.
WRINKLES: Distortions in backing materials represented
by creases, folds and other minor ridges or corrugated type defects
which interrupt the continuous, smooth nature of the web. Wrinkles
may be encountered running in any direction on the web.
YIELD STRENGTH: The force which when applied to tape will
cause it to stretch, such that it will not return to its original
dimension when the stress is removed.
