oxygen permeability


Also found in: Wikipedia.

oxygen permeability 

The degree to which a polymer allows the passage of a gas or fluid. Symbol: Dk. Oxygen permeability (Dk) of a material is a function of the diffusivity (D) (that is the speed at which oxygen molecules traverse the material) and the solubility (k) (or the amount of oxygen molecules absorbed, per volume, in the material). Values of oxygen permeability (Dk) typically fall within the range 10-150 ✕ 10−11 (cm2 ml O2)/(s ml mmHg). A semi-logarithmic relationship has been demonstrated between hydrogel water content and oxygen permeability. Unit: Barrer.The International Organization for Standardization (ISO) has specified the permeability of contact lenses using the SI unit hectopascal (hPa) for pressure. Hence Dk = 10−11 (cm2 ml O2) /(s ml hPa). The former unit can be converted to this new SI unit by multiplying it by the constant 0.75. The ISO has established a classification of contact lens materials based on a range of values of oxygen permeability Dk. Group 1: 1-15; group 2: 16-30; group 3: 31-60; group 4: 61-100; group 5: 101-150; group 6: 151-200; group 7: 201-250; higher codes can be added in bands of 50. See Barrer; oedema; equivalent oxygen pressure; critical oxygen requirement; refractometer.
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann
References in periodicals archive ?
I am currently a research fellow at Aston University, working on a range of clinical trials investigating areas like the ocular impact of UV, the benefit of UV filtering contact lenses, oxygen permeability of modern mini-scleral contact lenses and validation of new digital assessment tools.
Glass prefilled syringes are a widely used drug injectable system for parenteral drugs owing to its compatible features, for instance, higher stability, oxygen permeability and non-reactive nature.
Additionally, the oxygen permeability of EVOH films for packaging market deteriorates after retorting, which makes it the foremost need for manufacturers to improve the characteristics of EVOH films to withstand normal handling abuse and retort temperatures.
Films were first evaluated regarding their oxygen permeability, and then color changes, lipid oxidation and microbial growth on beef hamburger samples were determined.
"Silicone is flexible and has good oxygen permeability," said Hongjie Jiang, a post-doctoral researcher at the varsity.
The morphology and physical properties including tensile strength, elongation, water and oxygen permeability and transmittance were studied.
The 1.55 mm thick lens has a larger diameter and more oxygen permeability than typical soft contacts.
There were packaging P1 (polyethylene terephthalate/polyethylene), with oxygen permeability 60.00 [cm.sup.3]/([m.sup.2] x 24h x 0.1MPa), and packaging P2 (polyethylene terephthalate/aluminum/ethylene acrylic acid copolymer/polyethylene), with oxygen permeability 0.23 [cm.sup.3]/ ([m.sup.2] x 24h x 0.1MPa).
Oxygen Permeability. The oxygen permeability (OP) of WH-based composite films was determined with a VAC-V1 permeability analyzer.
Fletcher has observed that the oxygen permeability of a Saranex liner will vary because of spring tension in the capper heads.