All plastics have a minimum temperature rating. At this temperature the material becomes brittle and its impact strength has been significantly reduced causing it to be susceptible to cracking when under stress or pressure.
Water expands when frozen and the pressure this creates is sometimes enough to crack plastic, especially those that are brittle at temperatures below freezing. Room can be left in containers to account for this expansion but it is not always able to prevent damage to a container.
Polypropylene and PVC are both plastics that are brittle at temperatures below freezing. Polystyrene is considered brittle at 68°F and is very brittle at temperatures below freezing. High, medium and low polyethylene on the other hand, remains impact resistant at low temperatures. Polycarbonate and PETG also have low brittleness temperatures.
It is up to our manufactures to determine if a container is considered freezer safe or not. While it may be generally thought that plastic containers that are able to handle freezing temperatures without becoming brittle are safe, we can make no guarantees. We do recommend that when a plastic container is used that you leave enough head space to account for the expansion of the media being frozen.
Title: What plastics are freezer safe?
Description: Basic info on what plastics are freezer safe
Last Edited: 9/19/2013
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