Permeability coefficient of oxygen

Permeability coefficient of oxygen in nylon 6 as a function of water activity at 23°C [3]... 

Permeability coefficients of oxygen in amorphous nylon as a function of relative humidity [2]... 

The separation of oxygen from air is extremely important in connection with medical treatments, combustion processes, etc. Relatively thin effective membrane layers are required for practical oxygen separation systems, because the permeability coefficients of oxygen of most polymers are lower than those of hydrogen and carbon dioxide. 

Permeability coefficient of Oxygen at 30 C measured in this lab. "Formic acid at 30 C. THFat30 C. 

The barrier properties of starch nanocrystals/natural rubber nanocomposites were also investigated [39]. For these systems, the water vapour transmission rate, the diffusion coefficient of oxygen, the permeability coefficient of oxygen and its solubility, were measured. It was observed that the permeabiUty to water vapour, as well as to oxygen, decreased when starch nanocrystals wctc added These effects were ascribed to the platelet-like morphology of the nanocrystals. 

Example Calculate the permeability coefficient of oxygen through PET at 50°C (P2) considering that the permeability coefficient at 25°C (P ) is 220 cc-mil/m -d-atm. 

Table 14.6 presents the permeability coefficients of oxygen, nitrogen, carbon dioxide, and water vapor in several common polymers. 

Dependence of PO2 on bentonite loading for PEA/bentonite nanocomposites (PO2 permeability coefficient of oxygen). 

The permeability coefficients of oxygen and nitrogen in the polyphenylene oxides and hence the permselectivities were found to be pressure independent in the interval 1-7 atm. 

Figure4.3 Oxygen permeability coefficients of poly (2,6-dimethyl-1,4-phenylene oxide) (PPO) films of various thicknesses, as a function of aging time at 35 °C [52], Reproduced with permission of the American Chemical Society.

A precondition for the optimization of a package having a specified minimum shelf life date for a food with a known oxygen and/or water sensitivity is the calculation of the permeability of laminate structures. The total permeability Qv of a laminate film made from n different plastic layers with thicknesses d, and having permeability coefficients of Pj can be calculated using the following formula ... 

The second generation of nonporous membranes was silicon based which displayed increased CO2 permeabilities. In 1965, Bramson et al. commercialized the first nonporous membrane BO [18]. Since the diffusion coefficient of oxygen and carbon dioxide in air is about four orders of magnitude higher than in blood, the gas side mass-transfer resistance was negligible. The major resistance to respiratory gas transfer was due to the membrane and the liquid side concentration boundary layer [19]. Though nonporous membrane BOs reduced blood damage, up to 5.5 m membrane surface area was often required to ensure adequate gas transfer rates. 

Stancell et. al. ( 0) reported the possible use of ultrathin films deposited onto relatively permeable substrates as permselective membranes. Ultrathin and highly crosslinked coatings effectively distinguish between molecules of different sizes and increase the permselectivity of the substrate film. Chang et. al. ( ) demonstrated that the permeability coefficient of silicone rubber to oxygen decreased noticeably after depositing a plasma-polymerized ethylene film on the surface. Colter, et. al. (92.93) found similar effects of plasma polymerized films as diffusion barriers in controlled-released drug delivery systems. 

Not only is there negligible Retort Shock, but with desiccant containers, a lag time to reestablish oxygen barrier in the EVOH is not detectable. In fact, a very low permeability coefficient of 0.02 is established within seven days of retorting, the minimum time period at which permeability can be measured. The high initial oxygen permeation rate, that is seen immediately after retorting with non-desiccant containers, is never seen with desiccant containers. 

Calculate the total oxygen permeability coefficient of the following multilayer structure (P given in cc mil/100 in d atm, thickness in mils). 

Olson et al. [2003] carried out PALS studies of 22 poly(ethylene terephthalate) (PET) specimens with varying degrees of crystallinity 11 specimens were melt-crystallized at 210°C and 11 were made via cold crystallization at 110°C. Each sample was characterized thoroughly by DSC and WAXD in terms of Tg, Tm, and Xc, and, in fact, prior to the PALS investigation, were employed in a study of oxygen permeability at room temperature, which demonstrated that the O2 solubility in the melt-crystallized PET is higher than in the cold-crystallized PET [Lin et al., 2002]. This earlier work further established that the observed decreases in solubility and diffusion coefficient of oxygen in semicrystalline PET could be explained by the three-phase model of semicrystalline polymers, in which the RAF is considered in... 

Fig. 5 shows the effect of aging time on the permeability coefficient for oxygen in PMSP, poly(TMSP-co-PP), and PMSP/PPP blend membranes at 30°C. This figure also shows the effect of PP content in the copolymer and PPP content... 

Figure 5. Oxygen permeability coefficients of (alkylsulfonyl)methyl-substituted poly(oxyethylene) as a function of the number of carbon in the alkyl side chains.

It can be seen that the diffusion coefficient of the large pentane molecule is 3.6 times smaller than the diffusion coefficient of oxygen. However, the solubility of pentane is about 200 times larger than the solubility of oxygen. This solubility selectivity outnumbers the reverse diffusion selectivity. As a result, silicone rubber is much more permeable for pentane than for oxygen. 

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