Polymer and Materials Science
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Plastic bottles for carbonated beverages have many advantages over glass and metal containers. However, plastic bottles are also known to be imperfect barriers for gaseous fluids; i.e., they are semipermeable. This characteristic results in serious carbon dioxide transmission losses, particularly on the ½-L or smaller single-service bottles which have high area-to-volume ratios. Shelf life of these smaller beverage containers is therefore reduced. This article combines literature data and a simple diffusion model to predict shelf life for PET beverage bottles. As anticipated, the model shows that the smaller bottles have an unacceptable shelf life based on industrial standards. Moreover, while refrigerated temperatures increase shelf life to acceptable levels, temperatures for storage above 100°F can also reduce the 2-L bottle to less than acceptable levels. The shelf life predictions developed with the model are close to those observed in practice. Further manipulation with the model shows that a hypothetical multilayered barrier wall could be constructed which would give an acceptable shelf life at any reasonable temperature.
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