oxygen permeability


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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.
References in periodicals archive ?
a set for shelter of ten silo trenches with the size of 16x50m comprising: - a polyethylene silage film with oxygen permeability not more than 5 cm3 / 1m2 / 24h, thickness 120-150 microns, resistance to tearing not less than 400 kg, length in accordance with the size of the trench- protective net against birds and rodents, external mechanical stress, woven protective net-structure of at least 73 threads per 10cm
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.
However, innovating the wound irrigation solutions by enhancing their ability to retain moisture balance and ingraining extended oxygen permeability and antimicrobial activity along with availability of expanded product line for wound care are factors also expected to drive the growth of the wound irrigation solution market in North America and Europe over the forecast period.
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.