• Plastics 101
  • Site Information

     Loading... Please wait...


    Too Hot or Too Cold! What Temperatures Can Your Plastic Containers Endure?

    Posted by Cody Voelker on

    Common questions at ePackageSupply include "Is this container freezer grade?"  "Is this bucket microwavable?"  Though all our plastic buckets are made technically from the same material, i.e. plastic, different polymers withstand different temperatures.  At ePAckageSupply, we sell packaging supplies that may contain polypropylene (PP), high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and polyethylene terephthalate (PET).  Which one can you freeze?  Which one can you heat?  Can any do both?  We are here to help answer these questions.


    Image result for polyethylene

    Polypropylene (Random)

    Can withstand reheating in microwavePolypropylene comes in two variations.  The first is a random co-poly resin.  This random co-polymer polypropylene is usually used when a softer and clearer option is desired.  This soft, clear exterior characterizes the plastic and is "random" because the co-monomer units (the things used to connect molecules to make our wondrous plastic, well 

    lastic) are arranged in random and irregular pattern around the molecule.

    Melt Temperature - 130 Degrees Celsius ( 266 Degrees Fahrenheit ) 

    Freezing "Crack" Temperature - 0 Degrees Celsius ( 32 Degrees Fahrenheit )

    In use, random co-poly polypropylene (PP) is brittle resistant, NOT crack resistant.  This means that these softer and clearer plastics should not be exposed to freezing temperatures.  They are, however, safe for reheat application in a microwave.  At, each of our listings state what kind of plastic they are made out of.  If you see PP or read the words co-poly or polypropylene, then to determine if the product is safe to keep in freezer, go off of the color of the plastic.  The clarified material is the random co-polymer.  The smokey (or translucent) or white colored containers are our second type of polypropylene material:  impact co-poly polypropylene (PP). 

    Polypropylene (Impact)

    plastic can withstand temperatures of a freezer

    Impact co-poly polypropylene (PP) is essentially the same as the above.  However there are subtle differences that make the impact co-polymer polypropylene better for some uses.  As mentioned above, the impact PP comes in a smokey color we call translucent and solid white.  However, these are listed with our random PP buckets.  The down part to this plastic is that it cannot be clarified.  But what it lacks in easy visibility it gains in temperature flexibility.  Below are the temperature ratings for impact co-poly polypropylene.

    Melt Temperature - 130 Degrees Celsius ( 266 Degrees Fahrenheit)

    Freezing "Crack" Temperatures - -20 Degrees Celsius ( -4 Degrees Fahrenheit )

    So, the impact plastic is a more rigid, glossier material that actually withstand temperatures as low as -4 degrees Fahrenheit, which means it usually can sit in frozen environments such as food freezers.  It also can  withstand temperatures high enough so you can reheat it in a microwave!

    For more interesting polymer facts, take a look at

    ​Sustainability through Recycling – Making a Future for Your Children

    Sustainability through Recycling – Making a Future for Your Children  5 Facts about recycling that are hurting the next generation You have heard it before and you will probably continue to hear it. Generations of people are leaving this planet off worse than when they found it. It’s a situation that even after our greatest efforts, human beings are still [...]

    Read More »