Glossary - V's

Vacuum evaporation (sc) a deposition technique whereby the deposited gas results from an evaporation process.

Van der Waals force an attractive force between two atoms due to a fluctuating dipole moment in one molecule inducing a dipole moment in the other molecule which then interact.

Vapor pressure the pressure of the vapor in equilibrium with its liquid or solid phase.

Virtual leak (sc) an “apparent” leak in a vacuum system that is often traceable to some internal release of occluded and/or sorbed gases.

Viscoelasticity (r) a combination of viscous and elastic properties in a material with the relative contribution of each being dependent on time, temperature, stress and strain rate. Viscosity the resistance of a material to flow under stress.

Viscosity, Mooney (r) a measure of the viscosity of a rubber or rubber compound determined in a Mooney shearing disk viscometer.

Void, cellular material (r) a cavity unintentionally formed in a cellular material and substantially larger than the characteristic individual cells.

Volatilization also known as vaporization, the conversion of a chemical substance from a liquid or solid state to a gaseous or vapor state.

Volt a unit of electromotive force or difference in electric potential.

Volume swell (r) the increase in dimension caused by the absorption of a fluid.

Vulcanizate (r) the product of vulcanization, a cross-linked rubber.

Vulcanization (r) an irreversible process during which a rubber compound, through a change in its chemical structure (for example, cross-linking), becomes less plastic and more resistant to swelling by organic liquids, while elastic properties are conferred, improved, or extended over a greater range of temperature.

Vulcanizing agent (r) compounding material that produces cross-linking in rubber.

Vulcanizing system (r) the combination of a vulcanizing agent and, as required, accelerators, activators and retarders used to produce the desired vulcanization characteristics or vulcanizate characteristics.