Dry ice is solid carbon dioxide. At normal atmospheric pressure and temperature it sublimates (changes directly from a solid to a gas), resulting in a tremendous increase in volume.
To calculate the amount of pressure that occurs in a 0,5L PET bottle when a specific amount of dry ice is inserted and then heated up, we can apply the Van der Waals equation, which is a revised version of the ideal gas equation, used to more accurately describe the behavior of real gasses.
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Therefore, if, for example, we have a PET bottle of V=0.5L and room temperature
T= 20° C +273= 293K, then 3gr of dry ice are going to produce 3.23atm pressure.
According to design specifications, a PET bottle for carbonated products can hold up to 13,6 atmospheres of pressure before it bursts. This level of pressure can be reached if 13,3 grams of powdered dry ice are inserted in the bottle.
The maximum level of pressure that a bottle can hold depends of course on the thickness of the PET vessel (ex. 0.5 liter Sprite PET bottle, 0,45 mm thick has burst pressure =13.6atm) and the configuration of the bottle (ex. a five-footed bottle base gets less distorted than a four-footed base). Nonetheless, 13gr of dry ice can be the starting value for the experiments.
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Performance of 20g and 22gr 0,5L bottles in 4- and 5-foot base variations Source: Raising the bar in PET bottle lightweighting - WRAP |
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