Table of Contents
Reviewed and updated by ICD - Week 43/2026
Neither is better in every case: PP handles heat better and is stiffer, while HDPE handles cold better; choose by working temperature, load and impact. HDPE plastic (high-density polyethylene) and PP (polypropylene) are both lightweight polyolefins that float on water and resist chemicals well, so they are often confused when choosing bins and pallets. I am Le Van Thang, in charge of plastic materials at ICD Vietnam since 2011; the question customers ask most is “should my pallet be PP or HDPE”, and the answer almost always starts with the temperature of the warehouse.
What is HDPE plastic?
HDPE is high-density polyethylene. Its chains have few branches, so it is stiffer and less permeable than LDPE. Its melting point is about 132 °C according to Wikipedia, and its resin identification code is 2. HDPE stays tough at low temperature: a study published in Polymers in 2021 puts the ductile-to-brittle transition of polyethylene below about -73 °C, which is why HDPE is used as a coating for pipelines in deep-cold regions.
Common HDPE applications are bottles, jerrycans, containers, pipes and plastic pallets. HDPE heat resistance has its own article in the Related articles section.
What is PP plastic?
PP melts at about 160-165 °C, has code 5, and a density of about 0.90-0.91 g/cm³, so it is lighter than HDPE (about 0.93-0.97 g/cm³). PP is stiffer, handles heat better and can be flexed repeatedly at a hinge, so it is used for flip-top lids and folding crates. US EPA material also summarises PP as the plastic with a higher working temperature and more stiffness than PE. Its weak points: homopolymer grades turn brittle in the cold (a PP tank maker lists brittleness at 0 °C) and need UV additives outdoors.
How are HDPE and PP similar?
Both are polyolefins, so they are lighter than water, inert to most acids, alkalis and alcohols at room temperature, and can be moulded, injection-moulded and extruded into many shapes. Both carry identification codes for recycling collection, but whether they can actually be recycled depends on the collection system in each place.
How do HDPE and PP differ?
| Criterion | HDPE | PP |
|---|---|---|
| Identification code | 2 | 5 |
| Melting point | about 132 °C | about 160-165 °C |
| Density | about 0.93-0.97 g/cm³ | about 0.90-0.91 g/cm³ |
| In the cold | Tough down to about -73 °C | Homopolymer turns brittle around 0 °C; copolymer has better impact resistance |
| In the heat | Melts about 30 °C lower than PP, so its heat limit is lower | HDT 95-102 °C (0.45 MPa); Vicat 85-92 °C |
| Environmental stress cracking | Depends on the resin grade: some are very good, some only moderate | Not affected by slow crack growth, per INEOS documentation |
Sources of the figures: Wikipedia for HDPE melting point and density, Basell and Ducor data sheets for PP, Poly Processing and Simona for cold behaviour, INEOS for environmental stress cracking.
Which is better, HDPE or PP?
Where does HDPE win?
HDPE is better in the cold: pallets and bins used in cold rooms or freezers should favour HDPE or PP copolymer, because homopolymer PP turns brittle near 0 °C. HDPE also has its own recycling figure: the EPA records a recycling rate of 29.3% for natural HDPE bottles in 2018, while PP falls under other packaging and has no separate figure.
Where does PP win?
PP is better in the heat and where stiffness matters: hot-wash crates, reheating trays, bins placed near heat sources and parts that need a living hinge. PP is lighter, which cuts transport cost, and according to INEOS PP does not suffer slow environmental stress cracking the way some HDPE grades do.
See also: HDPE heat resistance.
How to tell PP from HDPE
The surest way is to read the identification code on the underside of the product: 5 is PP, 2 is HDPE (the code system follows ASTM D7611). For a product with no code, ask the supplier for the resin grade instead of guessing from the surface or the smell when burned, because these methods depend on additives and colour and have no standard reference. Both have a density below 1 and float on water; PP floats a little higher.
Conclusion
HDPE suits cold and impact, PP suits high heat and stiffness. The final decision lies in working temperature, load and conditions of use; when unsure, ask for the resin data of the exact product line.
Frequently asked questions
How do PP and HDPE differ?
PP melts at about 160-165 °C, has code 5, and is stiffer and more heat-tolerant; HDPE melts at about 132 °C, has code 2, and is tougher in the cold.
What are the main advantages of HDPE?
It is tough at low temperature (brittle only below about -73 °C), resists chemicals, absorbs no water, and is used for bottles, jerrycans, bins, pipes and pallets.
What are HDPE and PP used for?
Both make containers, jerrycans, plastic pallets and lids; HDPE leans towards bottles, jerrycans and pipes, while PP leans towards boxes, lids and heat-resistant parts.
Contact ICD Vietnam for bin and plastic pallet advice
ICD Vietnam Industrial Manufacturing Co., Ltd.
North: 3rd Floor, Thang Long A1 Building, Bau Hamlet, Thien Loc Commune, Hanoi, 0983 797 186 / 090 345 9186 / 090 5859 186
South: 551/212 Le Van Khuong Street, Tan Thoi Hiep Ward, District 12, Ho Chi Minh City, 098 6784 186
Email: sales@icdvietnam.com.vn
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References
- Wikipedia, Polypropylene (melting point, history, clarity, applications) - en.wikipedia.org
- Basell, Moplen HP500N datasheet (HDT, Vicat, density) - pimd.vn
- Ducor Petrochemicals, DuPure G 72 TF datasheet (haze, density, temperature) - ducorchem.com
- Poly Processing, Polyolefins technical data (PP brittle at 0 °C, UV, autoclaving) - tanks.polyprocessing.com
- Simona, technical Handbook (PP homopolymer brittle in the cold, copolymer impact resistance) - simona.de
- INEOS, Environmental Stress Crack Resistance of Polyethylene - ineos.com
- Salakhov et al., Low-Temperature Mechanical Properties of High-Density and Low-Density Polyethylene, Polymers 2021 (HDPE brittle below about -73 °C) - pmc.ncbi.nlm.nih.gov
- Wikipedia, High-density polyethylene (melting point about 132 °C)
- US EPA, Containers and Packaging: Product-Specific Data (2018 recycling rates) - epa.gov
- Wikipedia, Resin identification code (codes per ASTM D7611)
