ABSTRACT
Permeability is defined [1,2] as the amount (volume) of gaseous material (diffusing species) at a specified temperature that passes through a polymer or material film of unit thickness per unit cross-sectional area, at a unit pressure difference per unit time. Gas permeability characteristics of thermoplastic resins play important roles in their packaging and environmental-stress-cracking resistance (ESCR) behavior and performance. Permeability is commonly expressed in units of cm3 · cm/cm2 Pa s. This unit reduces to cm2/Pa s. Another form of this unit is cm3 cm/cm2 s cm Hg. The Barrer unit is used in the literature as the basic unit of permeability. The Barrer is equivalent to 7.5E−14 cm3 · cm/cm2 Pa s or 1.0E−10 cm3 cm/cm2 s cm Hg. Other units are also used.
