When do I Need True Freezer Grade Plastic Pallets?

OK, so you run a cold storage operation and the FDA has been in a time or two talking about the FSMA and other interesting subjects. So far you are in full compliance, but you thought it might not be a bad idea to look into switching to plastic pallets for your sub-freezing storage. 

Any operation with consistent temperatures below 0°F should consider using true freezer grade pallets.

Where Do I Even Begin?

No reason to panic. The truth is that MOST plastic pallets available on the market today can withstand temperatures below 32°F without any difficulty. You are at minus 30°F? Holy Cow - that is cold! And, yes, you WILL need a true freezer grade pallet.

So what makes plastic freezer pallets truly freezer grade? Captain Obvious will tell you, the one that works well in a freezer. One that has the stiffness to do its job as a pallet but one that does not get brittle in cold temperatures. Dah. 

Here are the two main factors that will impact performance in the freezer:

1. Material
   Simply put, some plastic resins do better in the cold than others. More on that in a bit.
     
2. Wall Thickness
   Some of the foibles of polypropylene (PP) and other less cold-resistant resins can be overcome simply by making the parts thicker. A PP part at 3/8" thick will be less likely to fail in the cold than say one at 1/8" thick.

Tell Me More About Plastic Resins for Freezer Use

As I mentioned above, brittleness must be considered in material choice. Here's some good info to have:

• LDPE and HDPE
  Both do well in the cold. Not unusual to see brittle thresholds of -50°F for some grades.
   
• PP and PVC
  These can become brittle even at moderately cold temperatures. Many generic PP grades will get brittle at around 32°F. 
   
• Polystyrene
  This gets brittle if you give it the cold shoulder.
   
• Structural Foam
  Any resin that has been foamed (as in structural foam) will also become more brittle in the cold than a part molded of the same material but not foamed. 

What About Recycled Material?

Good question. Most applications can be adapted to pallets made from recycled plastic material. When it comes to freezer grade, however, material engineers need to be consulted.

The same material that does well as a virgin, unblended resin will lose physical properties each time it is recycled. To combat this, the better engineered pallets will add an elastomer filled resin like TPO to the mix. In layman’s terms, this is like adding rubber to the plastic. The chemistry behind all of this can be like voodoo and is often a well-guarded secret. For us, it means the pallets will still be stiff enough to do their jobs, but will not get brittle when they are cold.


I Think I Need a True Freezer Pallet. Now What?

​To recap, if your work environment is really cold, say lower than 0°F, you should consider a true freezer grade pallet when buying plastic. If you intend to use a pallet molded from virgin material, ask specific questions about the material from which that pallet is molded. Working temperature ranges are listed for all plastic resins, and your supplier should have that data in writing. If you are considering pallets with recycled content, look for a supplier that offers an engineered solution, specifically addressing your low temperature needs.

Still confused? Best to reach out to a pallet professional or you can post your questions here.
​
Post by: Hartson Poland, Business Development - Plastic