Polyethylene oxygen permeability

Table 12. Effect of Calcium Carbonate Fillers on Oxygen Permeability of Low Density Polyethylene...

Fig. 15. Oxygen permeability versus 1/specific free volume at 25 °C (30). 1. Polybutadiene 2. polyethylene (density 0.922) 3. polycarbonate 4. polystyrene 5. styrene-acrylonitrile 6. poly(ethylene terephthalate) 7. acrylonitrile barrier polymer 8. poly(methyl methacrylate) 9. poly(vinyl chloride) 10. acrylonitrile barrier polymer 11. vinyUdene chloride copolymer 12. polymethacrylonitrile and 13. polyacrylonitrile. See Table 1 for unit conversions.

Polyethylene terephthalate) (PET), with an oxygen permeability of 8 iiiuol/(ius-GPa), is not considered a barrier polymer by die old definition however, it is an adequate barrier polymer for holding carbon dioxide in a 2-L bottle for carbonated soft drinks. The solubility coefficients for carbon dioxide are much larger than for oxygen. For the case of the PET soft drink bottle, the principal mechanism for loss of carbon dioxide is by sorption in the bottle walls as 500 kPa (5 atm) of carbon dioxide equilibrates with the polymer. For an average wall thickness of 370 pm (14.5 mil) and a permeabdity of 40 nmol/(m-s-GPa), many months are required to lose enough carbon dioxide (15% of initial) to be objectionable. 

A novel organic (chitosan) and inorganic (tetraethyl orthosilicate) composite membrane has been prepared, which is pH sensitive and drug permeable [258]. The latter possibly involved in ionic interactions. By plasma source ion implantation technique, the adhesion between linear low-density polyethylene and chitosan could be improved [259]. Such bilayer films showed 10 times lower oxygen permeability, a property of use in food packaging applications. These multilayer films were easily recyclable. 

Figure 8. Dry oxygen permeability of 38 m oriented polypropylene, 135 jX. ffl low density polyethylene and 13 m polyester, treated with varying thicknesses of the silane primer. These data were recorded with a Modern Controls Inc. Oxtran 1000 permeability analyzer.

Vernon Krieble, chairman of the Chemistry Department at Trinity College in Hartford, Connecticut, learned about the product through his son, Robert Krieble, who was employed at General Electric. Vernon Krieble found a chemical solution to the problem by using cumene hydroperoxide (I) (see Section XII for all structures) as the initiator and packaging in half-filled oxygen-permeable polyethylene bottles [8]. He licensed the GE patent and in 1954 founded the American Sealants Corporation, which later became Loctite Corporation [9]. At the present time anaerobic adhesives and sealants are manufactured or sold on every continent by more than a dozen companies. Applications in virtually every industry, and technological iimovation, as measured by patent activity, continue unabated. 

Xanthos, M., Faridi, N., and Li, Y. (1998) Processing/structure relationships of mica-filled polyethylene films with low oxygen permeability. Int. Polym. Process.,... 

However, beside PI, P2 and the perfluorated poly(norbornadiene) P9, the oxygen permeabilities of most ROMP polymers, measured on films of 20-100 pm thickness [11], are relatively low, not sufficient for applications as contact lenses. The values are comparable to saturated hydrocarbons like low density polyethylene (LDPE) which has an oxygen permeability of 2.6 barrer, measured under similar conditions [11]. The situation is different for mono- and disubstituted poly(acetylenes), which will be discussed in part 2. 

Suppository strips for pharmacy preparations often consist of aPVC-polyethylene laminate PVC has the advantage that it shows relatively little permeability to water vapour and oxygen. It has the disadvantage that it always contains softeners that could migrate into the suppository. In the case of polyethylene the permeability to water vapour is comparable to that of PVC, but the permeability to oxygen is greater. The used polyethylene does not release additives. 

Sadler, G. D. and Braddock, R. J. Oxygen permeability of low density polyethylene as a function of limonene absorption An approach to modeling flavor scalping. Journal of Food Science, 55, 587-588 (1990). 

Wang, Y, Allan, J. E., and Chen, X. D. Ethylene and oxygen permeability through polyethylene packaging films. Packaging Technology and Science, 11, 169-178 (1998). 

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