Oxygen transmissibility

Paper is one of the oldest and most commonly used packaging materials. Generally it is used to keep a product clean and for mechanical strength when combined with other materials. It does not protect a product from atmospheric change, but only from mechanical contaminants such as dirt. Coated papers are much more functional. Waxed papers fall into this category and provide much better protection from moisture and, in some cases, from gas (oxygen) transmission. 

FIGURE 2.11 Plot of oxygen transmission rate versus time for brominated poly(isobutylene-co-isoprene) (BIMS) nanocomposite. 

Honeywell has also been active in developing a combined active-passive oxygen barrier system for polyamide-6 materials [201]. Passive barrier characteristics are provided by nanoclay particles incorporated via melt processing techniques, while active contribution comes from an oxygen-scavenging ingredient (undisclosed). Oxygen transmission results reveal substantial... 

Pike, L., Measurement of Oxygen Transmission Rates of Film and Thin Sheeting Under Humid Conditions, TAPPI Proceedings, Polymers Laminations and Coatings Conference (1986). 

If the depletion layer is completely inside the stagnant layer, the current is not affected by the change of flow. From (7.18), we know that this happens when the electrode radius becomes small. For Clark-type electrodes, the flow insensitivity is obtained even for larger diameters of the electrode, because of the additional confining effect of the membrane which has lower oxygen transmissivity, DmSm, than that of the solution. 

One recent example of the formation and application of foils/membranes of unmodified bacterial nanocellulose is described by George and coworkers [35]. The processed membrane seems to be of great relevance as a packaging material in the food industry, where continuous moisture removal and minimal-oxygen-transmission properties play a vital role. The purity, controllable water capacity, good mechanical stability, and gas-barrier... 

For the purification of the membranes, the common treatment with 0.1-2.0 N aqueous sodium/potassium hydroxide solutions has been compared with the purification of raw BC membranes using aqueous sodium/ potassium carbonate. Whereas hydroxide purification leads to a decrease of the tensile strength and an elongation of the material this effect is lower in the case of carbonate treatment. Moreover, the oxygen transmission rate is higher after carbonate washing. 

Mortensen, G., Sorensen, J., Stapelfeldt, H. 2002. Effect of light and oxygen transmission characteristics of packaging materials on photooxidative quality changes in Havarti cheeses. Packaging Technol. Sci. 15, 121-127. 

Gas barrier properties - Metabolix PHA polymers have lower moisture vapour transmission rates than other biodegradable polymers. The oxygen transmission rates for unoriented PHA films are 25-30 cc-mil/(100 in2-day) at 77 °C, 0% relative humidity. 

Compared with PTFE, fluorinated pitch has a higher oxygen transmission constant, but a lower separation ratio a. 

Provides tear and puncture resistance. Relatively low oxygen transmission. 

Provides excellent barrier to oxygen transmission when dry. 

Water vapor and oxygen transmission (WVT and O2T) are commonly measured on thin-film specimens. Butyl and halobutyl compounds have very low WVT and O2T rates, while rates for natural and isoprene rubbers are higher and for silicone even higher. 

CGA G-4.4, Industrial Practices for Gaseous Oxygen Transmission and Distribution Piping Systems, Compressed Gas Association, Arlington, VA, 1993. 

The water vapor and oxygen transmission rates of single films of va-... 

With the water content of the EvOH available from integration of eqn 1, the oxygen transmission rate of the package, OxTr, is calculated from ... 

The barrier performance of rigid containers was measured on both a second modified MOCON instrument and by a head space technique in which nitrogen purged and sealed containers were stored in an oxygen environment for periods of time. Containers were generally measured at 23°C with 100% relative humidity (RH) inside and either 50 or 75 RH outside. Container oxygen transmission rates (OTR) are expressed as cm30 /container-day-atm. 

The effect of orientation on oxygen permeability of the medium and high barrier resins is seen to be dependent upon the morphological nature of the barrier resin prior to orientation. A plot of the oxygen transmission rates as a function of the overall draw ratio (figure 3) illustrates this clearly. While the semicrystalline polymers, VDC copolymer, and aromatic nylon MXD-6, show little change in the permeability with moderate amounts of orientation in the solid state, orientation of the amorphous polymers SELAR PA 3426 and XHTA-50A causes reduction in the permeability by 5-30% in both resins, depending upon the overall level of orientation. 

Figure 3. Oxygen transmission rates as a function of the overall draw ratio, illustrating the dependence on the morphological nature of the barrier resin prior to orientation.

Further characterization of the synergistic effects of overcoating metal layers with the barrier polymer was done using simple flat polystyrene films of 5 mil thicknesses that had been surface sulfonated to provide a low degree of sulfonation of 1.5 micrograms of sulfur trioxide per cm2. Two strips of the surface sulfonated film were coated with different thicknesses of the same barrier polymer as that used above. An additional sulfonated strip was not coated, but was metallized as described above, and a final strip was both metallized and coated with a layer of 0.22 mils of barrier polymer. The results of oxygen transmission measured by mass spectrometer at 25°C are reported in... 

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