Table of Contents
- Quick summary
- Heat resistance of PP
- Why the thermal properties of PP matter
- Factors affecting the heat resistance of PP
- Uses of PP in hot environments
- Comparing PP with other plastics for heat resistance
- Recommendations for using PP safely around heat
- Conclusion
- Frequently asked questions
- Contact ICD Vietnam for crate and plastic pallet advice
- References
- Related articles
Reviewed and updated by ICD - Week 44/2026
PP has moderate heat resistance: it melts at about 160-165 °C, but a load-bearing product starts to soften from about 85-100 °C, so 100 °C does not melt PP but is already a zone for caution. Water at 100 °C is already boiling off while polypropylene (PP) still holds its shape; even so, the gap between “not yet melted” and “still usable” is where many people go wrong. ICD Vietnam has compiled the datasheets of resin makers to answer this specifically.
Quick summary
A melting point of 160-165 °C is where the material turns liquid. The practical limit is lower: the heat deflection temperature at 0.45 MPa of common PP grades is about 95-102 °C and only about 57 °C at 1.8 MPa; the Vicat softening temperature is about 85-92 °C (Basell and Ducor datasheets). So when we say PP is heat resistant, the accurate statement is that it is better than PE and enough for reheating and rinsing with hot water, but it is not a material for ovens or contact with hot metal.
Heat resistance of PP
Polypropylene is a semi-crystalline polymer, so it holds its shape as it heats up to close to its melting point, provided the product carries no load. The 160-165 °C figure is measured by differential scanning calorimetry on the resin; the FDA specification for PP homopolymer gives 160-180 °C. Under load, especially on crate walls, pallet legs and containers full of water, the material softens much earlier: that is the meaning of HDT and Vicat. Resin makers do not publish one continuous figure for every grade, because it depends on grade, thickness, load and exposure time.
The other direction matters too for cold storage and winter transport: a plastic tank maker warns that PP products are brittle at 0 °C, and the technical handbook of the sheet maker Simona states that homopolymer PP is brittle in the cold while copolymer with ethylene resists impact. The working window of PP is therefore from below 0 °C (depending on grade) to just under 100 °C, wider than PE toward the hot side but narrower toward the cold side for homopolymer.
Why the thermal properties of PP matter
Moderate heat resistance plus chemical resistance makes PP suit containers, returnable trays and packaging that must be washed in hot water. Ordinary chemicals at room temperature such as acids, dilute alkalis and alcohol do not damage PP, and one manufacturer’s technical document says PP does not suffer environmental stress cracking the way some HDPE grades do. UV is a specific weakness: polyolefins can all degrade when left in the light for long, so outdoor products need UV stabilizers. In processing, PP molds, extrudes and thermoforms well, so many shapes can be made at reasonable cost.
Factors affecting the heat resistance of PP
The same letters PP can hide considerable differences in heat limits between products, because of the following six factors.
- Resin type: homopolymer is stiffer and more heat resistant; random and block copolymers are more flexible, suited to impact resistance or clarity but usually soften earlier.
- Virgin or recycled: virgin resin has a uniform structure; recycled resin carries impurities and has been processed many times, so strength is usually lower, which calls for caution in hot spots and under heavy load.
- Additives: heat stabilizers and antioxidants extend life under heat; UV stabilizers are needed for outdoor use.
- Thickness: a thick wall transmits heat more slowly and is stiffer, so it handles heat better.
- Load and time: a large load plus high heat makes PP creep and soften; long exposure near the softening threshold shortens life.
- UV: long sun exposure ages PP, making it brittle and weak.
Uses of PP in hot environments
Food packaging. PP containers are a familiar choice for reheating food, but according to Harvard Health you should only microwave containers labeled microwave-safe; takeout containers and butter or ice cream tubs are not meant for this, a scratched or old container releases more, and the lid should be left slightly open to let steam out. PP in food contact must also meet rules such as the FDA’s 21 CFR 177.1520, which sets conditions on melting point and the amount of extractables.
Medical and laboratory equipment. A laboratory supplies vendor states that PP withstands autoclave sterilization, so PP is used for tubes, trays and instruments that must be disinfected. The same document warns that prolonged light can damage polyolefins.
Engineering parts and industrial fabric. PP appears in car plastic parts, equipment housings, geotextiles and filter media; in these uses manufacturers choose grades with suitable additives and stiffness, and do not use general-purpose PP in high-heat zones next to engines.
Pallets and plastic crates. Plastic pallets made from PP last longer than wooden pallets in humid environments and are not attacked by termites, so they are used in damp warehouses and supply chains that need hygiene. For hot warehouses or trucks in summer, ask the supplier for the maximum working temperature and load of that exact resin grade rather than using the melting point as your basis.
Comparing PP with other plastics for heat resistance
The table below uses only sourced figures. The melting point is a material limit, not a use temperature.
| Plastic | Melting | Identification code | Heat notes |
|---|---|---|---|
| PP | about 160-165 °C | 5 | HDT at 0.45 MPa about 95-102 °C; Vicat about 85-92 °C |
| HDPE | about 132 °C | 2 | Melts about 30 °C lower than PP, so it is less heat resistant |
| PET | about 250-260 °C | 1 | Melts much higher, but PET bottles soften around 70-80 °C, so they are not used for boiling water |
Recommendations for using PP safely around heat
Keep products within the heat limit stated by the manufacturer, which is clearly lower than the melting point. Use for the intended purpose: a container labeled only for the microwave does not go in an oven, and do not place a PP container on a stove or against a hot metal surface. Check products that meet heat often: warping, cracks, brittleness or discoloration are signs to replace. Identify the plastic by the 5 inside the triangle or the letters PP; that number only identifies the plastic type and does not say how many degrees the product can take.
Conclusion
PP melts at about 160-165 °C but its practical use limit is much lower and depends on resin grade, thickness, load and time. It is enough for reheating, rinsing with hot water and ordinary storage; it is not meant for ovens or very hot zones. To choose a PP pallet or crate for the right heat conditions, you can contact ICD Vietnam using the details at the end of this guide.
Frequently asked questions
What is the maximum temperature polypropylene can withstand?
The melting point is about 160-165 °C, but under load PP already softens from about 85-100 °C (HDT 95-102 °C at 0.45 MPa, Vicat 85-92 °C). The practical use limit is set by the manufacturer of each resin grade.
Does 100 °C melt PP plastic?
No. 100 °C is about 60 °C below the melting point, but it is already in the zone where load-bearing PP starts to soften and deform, so a thin PP product should not carry load at this temperature for long.
Is polypropylene suitable for storing food at high temperature?
Within limits: food-grade PP containers work well for moderately hot food. For the microwave, use only containers labeled as safe for it; do not use an oven or place them next to a heat source.
Contact ICD Vietnam for crate and plastic pallet advice
ICD Vietnam Industrial Production Co., Ltd.
Northern Vietnam: 3rd Floor, Thang Long A1 Building, Bau Hamlet, Thien Loc Commune, Hanoi - 0983 797 186 / 090 345 9186 / 090 5859 186
Southern Vietnam: 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
- US FDA, 21 CFR 177.1520 Olefin polymers - law.cornell.edu
- Harvard Health, Microwaving food in plastic: dangerous or not? - health.harvard.edu
- 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, autoclave sterilization) - tanks.polyprocessing.com
- Simona, technical Handbook (PP homopolymer brittle in the cold, copolymer impact resistant) - simona.de
- INEOS, Environmental Stress Crack Resistance of Polyethylene - ineos.com
- Wikipedia, High-density polyethylene (melts at about 132 °C)
- Wikipedia, Polyethylene terephthalate (melting point, glass transition temperature)
