Oxygen vapor transmission rate

Milliken s Hypetform HPN-20E carboxylic acid salt-based clarifying agerrt used at 1000 ppm in HDPE reduced moistitre and oxygen vapor transmission rate by 40%. ... 

Films or membranes of silkworm silk have been produced by air-drying aqueous solutions prepared from the concentrated salts, followed by dialysis (11,28). The films, which are water soluble, generally contain silk in the silk I conformation with a significant content of random coil. Many different treatments have been used to modify these films to decrease their water solubiUty by converting silk I to silk II in a process found usehil for enzyme entrapment (28). Silk membranes have also been cast from fibroin solutions and characterized for permeation properties. Oxygen and water vapor transmission rates were dependent on the exposure conditions to methanol to faciUtate the conversion to silk II (29). Thin monolayer films have been formed from solubilized silkworm silk using Langmuir techniques to faciUtate stmctural characterization of the protein (30). ResolubiLized silkworm cocoon silk has been spun into fibers (31), as have recombinant silkworm silks (32). 

The effect of plasticizers and temperature on the permeabiUty of small molecules in a typical vinyUdene chloride copolymer has been studied thoroughly. The oxygen permeabiUty doubles with the addition of about 1.7 parts per hundred resin (phr) of common plasticizers, or a temperature increase of 8°C (91). The effects of temperature and plasticizer on the permeabiUty are shown in Figure 4. The moisture (water) vapor transmission rate (MVTR or WVTR) doubles with the addition of about 3.5 phr of common plasticizers (92). The dependence of the WVTR on temperature is a Htde more comphcated. WVTR is commonly reported at a constant difference in relative humidity and not at a constant partial pressure difference. WVTR is a mixed term that increases with increasing temperature because both the fundamental permeabiUty and the fundamental partial pressure at constant relative humidity increase. Carbon dioxide permeabiUty doubles with the addition of about 1.8 phr of common plasticizers, or a temperature increase of 7°C (93). 

MethylceUulose reduces surface and interfacial tension. MethylceUulose forms high strength films and sheets that are clear, water-soluble, and oU-and grease-resistant, and have low oxygen and moisture vapor transmission rates (see Barrier polymers). 

Alger, M.M. andT.J. Stanley, "Oxygen Barrier of LEP Food Containers Effect of Humidity on the Water Vapor Transmission Rate", GE Corporate Research Memo Report MR45763 (1989). 

Permeability of Thermoplastic Containers to Packaged Reagents or Proprietary Products Oxygen Gas Transmission Rate Through Plastic Film and Sheet using a Coulometric Sensor Water Permeability of Geotextiles by Permittivity Permeability of Leather to Water Vapor... 

Figure 15.12. Oxygen permeability and water vapor transmission rate (WVT) behavior of PA-6/Amorphous PA-6I/6T blends at 95% RH.

The permeability coefficient, P, combines the effects of the diffusion and solubility coefficients. The barrier characteristics of a polymer are commonly associated with its permeability coefficient values. The well-known relationship P = DS holds when D is concentration independent and S follows Henry s law. Standard methods for measuring the permeability of organic compounds are not yet available. ASTM E96 describes a method for measuring the water vapor transmission rate. ASTM D1434 describes a method for the determination of oxygen permeability. 

Barrier Properties Exact Plastomers create controllable gas-permeable films for modified atmospheres, as well as gas-permeable films and packaging for such items as fresh vegetables, fhiits, flowers, and a growing range of other horticultural products. Users can select carbon dioxide and oxygen transmission rates (OTR) that meet their needs, with low water vapor transmission rates (WVTR) and high levels of clarity and gloss. " ... 

Barrier effects Oxygen and moisture vapor transmission rates can be affected by some dartflers. 

Figure 7.34 Dependence of the oxygen transmission and water vapor transmission rates through the PU-nanocomposites. Reproduced from Ref [46] with permission.

As the mol ratio moves in the direction of PVOH, the properties become more like those of PVCW. Moisture vapor transmission rate (MVTE) and moisture sensitivity increase, specific gravity increases, melting point increases, and processing sensitivity increases. Oxygen barrier increases, gas transmission decreases and stiffness goes up. 

Diffusion coefficients and solubility coefficients are the fimdamental parameters that control mass transfer in packaging systems. In practice, however, the permeability P is the most important of the permeation properties. Characteristic values for the permeability are the transmission rates (oxygen transmission rate, OTR water vapor transmission rate, WVTR). They indicate the amount of a given substance that passes a unit surface area of film per unit time, depending on the partial pressure gradient for a given temperature, the relative humidity and the given thickness of the film. 

Figure 21-3. Oxygen and water vapor transmission rates, (23° C), 100 pm film thickness, for commodity thermoplastics and special packaging polymers.

Figure 21-4. Oxygen and water vapor transmission rates for standard laminates and high barrier materials (layer laminating agent PVD physical vapor deposition).

The CNCs improve the barrier properties like oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) as well as mechanical properties like young s modulus and strength of PLA matrix (Okastnan et al., 2006). 

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