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HDPE vs PP pallets: why the sort matters

Last reviewed Nov 12, 20267 stages

The short answer

HDPE and PP are the two resins in nearly every plastic pallet. HDPE is tougher and more common. PP is more rigid. Recyclers sort them apart because they melt and mould differently.

Neither is better for recycling. Mixing them is the problem.

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A pallet is shredded and ground to flake, sorted by resin and colour, and moulded into a pallet again.

HDPE

Resin code 2. Density 930 to 970 kg/m3. Melts at 131.8 C. Tough and moisture resistant. The most common pallet resin. Hard to glue, so repairs are welded.

PP

Resin code 5. More rigid and better with heat and harsh chemicals. Nelson recommends it for unsupported racking. Used in rackable and some hygienic pallets.

Why they are sorted

A mixed flake makes a poor moulding. The two polymers do not blend cleanly. A moulder using HDPE regrind with PP in it sees defects.

Recycling difference

Both grind and remould. HDPE has the deeper market for pallet regrind. PP has fewer buyers but they are specific.

Telling them apart in the yard

HDPE feels waxy and bends a little before cracking. PP feels harder and snaps cleaner. A moulded triangle gives the number: 2 for HDPE, 5 for PP.

Why the difference matters for a buyer

HDPE and PP flake are sold into different parts. A moulder does not want a few percent of the wrong resin in the hopper.

What if you cannot tell

Choose not sure. A photograph of the underside, the maker and the model usually settles it.

HDPE and PP side by side

Property	HDPE	PP
Code	2	5
Feel	Tough, slightly flexible	Stiffer
Typical pallet	Nestable, one-piece	Rackable
Heat and chemicals	Good	Better
Recycled	Yes, sorted	Yes, sorted

What the sources say

blog.containerexchanger.comNorth American plastic pallets in the common sizes are about 5 to 6 in tall.
iccsafe.orgA 2010 insurer figure cited by ICC puts fire spread to a pallet above at about 18 minutes for plastic versus nearly 50 for wood.
en.wikipedia.orgHDPE has resin identification code 2, a density of 930 to 970 kg/m3, melts at 131.8 C and is hard to glue, so joints are usually welded.
nelsoncompany.comOnly pallets designed for unsupported racking carry a racking rating.
palletenterprise.comIn 2011 a Quebec court ruled that CHEP's identified blue pallets belong to CHEP and cannot be sold.
palletenterprise.comCHEP USA sued two California recyclers over CHEP-marked pallets they would not return; a Los Angeles court granted CHEP's motion to retrieve pallets in one case (article dated February 1, 2024).
nelsoncompany.comA used Nelson 48 x 40 x 6.3 in HDPE one-piece pallet weighs 49 lb with 30,000 lb static, 5,000 lb dynamic and 2,200 lb racking ratings.
en.wikipedia.orgResin identification codes do not indicate whether a product is recyclable; ASTM D7611 governs the coding.
en.wikipedia.orgMetal pallets are under 1 percent of the pallet market.
phsinc.comPHS lists 48 x 40 stackable plastic pallets with dynamic ratings of 2,500 to 5,000 lb and static ratings of 3,000 to 30,000 lb.
en.wikipedia.orgPlastic pallets can deform (creep) under heavy long-term loads and are hard to repair.
en.wikipedia.orgNFPA requires wood and plastic pallets to be stored outdoors or in a detached structure unless sprinklers protect them.
resource-recycling.comIn April 2017, HDPE HMW regrind from drums and IBCs was 24 to 27 cents per pound picked up in the US South (historical, not current).
aphis.usda.govUSDA APHIS lists plastic pallets among products not subject to APHIS regulation, as an alternative to wood packaging material.

Terms on this page

HDPE: High-density polyethylene, resin code 2. The most common resin in plastic pallets; tough and moisture resistant.
PP: Polypropylene. More rigid than HDPE and better with heat and harsh chemicals; used where rack stiffness matters.
Resin code: The number inside the triangle on a plastic part. HDPE is 2, PP is 5.
Resin identification code: Number on a plastic part for the resin, which does not itself say whether it is recyclable.
Welding repair: Plastic is hard to glue, so cracked parts are normally welded.
Rackable: Rated to sit on rack beams, with a stated racking load.
Racking load: Weight a pallet carries bridging an open span in unsupported racking. Often the lowest rating.
Flake: The small, irregular pieces a granulator makes. Flake is regrind before it is sold or melted.
Moulder: A manufacturer that melts regrind or pellets and forms them into parts, such as pallets.
Regrind: Plastic ground from used or scrap parts into flakes for moulding again.
Granulator: A machine with rotating knives that cuts plastic down to a set size, then pushes it through a screen.
Nestable: Empty pallets stack inside one another, cutting empty storage space by up to 75 percent.

Questions people ask

Is HDPE or PP better for recycling?

Neither. Keep them apart.

How can I tell them apart?

The code, the stiffness and the style.

Can they be mixed in one load?

They can be sent mixed. They are sorted before grinding.

Which resin is more common in pallets?

HDPE. PP appears in rigid and rackable pallets.

Can I mix them if I only have a few?

It is better not to. Describe them as separate lines.

Sources, reviewed Nov 12, 2026: Wikipedia, high-density polyethylene; Nelson Company, what material is used for plastic pallets; Wikipedia, resin identification code.