In non-Newtonian behavior, which is the usually case with plastics, the ratio varies with the shearing stress. Such ratios are often called the apparent viscosities at the corresponding shearing stresses. Viscosity is measured in terms of flow with water as the base standard. The higher the number, the less flow. Index voids Air or gas that has been trapped and cured into a laminate.
Porosity is an aggregation of microvoids.
Voids are essentially incapable of transmitting structural stresses or nonradiative energy fields. The percent of volatiles that are driven off as a vapor from a plastic or an impregnated reinforcement. Index volatiles Materials, such as water and alcohol, in a sizing or a resin formulation, that are capable of being driven off as a vapor at room temperature or at a lightly elevated temperature. Index volume fraction Fraction of a constituent material based on its volume. The volume resistance between two electrodes in contact with or embedded in a specimen is the ratio between the direct voltage applied to them and that portion of the current between them that is distributed through the volume of the specimen.