The short answer
For freezers and winter service, the safe choices are polyethylene (LDPE, LLDPE, HDPE, UHMW-PE), impact-copolymer polypropylene, TPU, impact-modified nylon and PC/ABS. Polycarbonate is good in thin, well-radiused parts. PTFE and FEP work down to cryogenic temperatures. Avoid PP homopolymer, general-purpose polystyrene, acrylic, unmodified rigid PVC and PVDF homopolymer wherever a cold part might be dropped or hit.
Cold rarely changes a plastic’s strength much. What it changes is the way the plastic fails: a part that dents or bends at room temperature can crack cleanly below freezing. The limits below are approximate, because the real limit depends on the grade, wall thickness, notches and how fast the part is hit.
Why plastics turn brittle in the cold
Every plastic has a ductile-to-brittle transition: a temperature range below which it cracks rather than yields under impact. For amorphous resins with no rubber phase, such as polystyrene and acrylic, the glass transition (Tg) is around 100°C (212°F), so they are glassy and brittle at room temperature and in the freezer alike. See glass transition vs. melting point.
Semi-crystalline resins depend on their amorphous phase. Polyethylene’s amorphous phase stays rubbery far below freezing, so PE stays tough. Polypropylene homopolymer’s amorphous phase has a Tg of roughly -20 to 0°C (-4 to 32°F), which is why it turns brittle in the freezer. Impact copolymers, ABS, PC/ABS and super-tough nylon add a rubber phase with a very low Tg that keeps absorbing energy in the cold. See amorphous vs. semi-crystalline plastics.
Data sheets show cold performance in a few ways: notched Izod or Charpy at -20, -30 or -40°C (-4, -22 or -40°F), a brittleness temperature (ASTM D746, the temperature at which half the specimens fail), or instrumented drop-weight results that report ductile or brittle failure. Compare like with like.
Approximate low-temperature limits
| Resin | Approximate low-temperature impact limit | Typical cold uses | Notes |
|---|---|---|---|
| LDPE / LLDPE | About -50°C (-58°F) and below | Freezer bags, film, squeeze bottles, flexible lids | Soft; low heat resistance |
| HDPE | About -40°C (-40°F) or lower in many grades | Freezer containers, coolers, drums, outdoor tanks | Low stiffness; ESCR matters with detergents |
| UHMW-PE | Well below -40°C (-40°F) | Snowplow and chute liners, cold-storage wear strips | Machined or compression molded |
| PP impact copolymer | About -20 to -40°C (-4 to -40°F), grade dependent | Freezer containers, totes, battery cases | Pick by low-temperature impact data |
| PP homopolymer (avoid) | Brittle near 0°C (32°F) | Not for cold impact | Random copolymer slightly better, about -5 to -20°C (23 to -4°F) |
| Polycarbonate | Unnotched about -40°C (-40°F); notched standard grades lose toughness between about 0 and -30°C (32 and -22°F) | Clear covers, lenses, cold-room guards | Radius corners; low-temperature grades available |
| PC/ABS | Many grades useful to about -30°C (-22°F) | Outdoor housings, automotive interior parts | Less notch sensitive than PC |
| Nylon, impact-modified | About -30 to -40°C (-22 to -40°F) | Ski and snowmobile parts, cable ties, clips | Plain dry nylon is brittle in the cold |
| TPU (polyether) | About -40°C (-40°F) and below | Cold-weather cable jackets, seals, wheels | Polyester types stiffen more |
| PTFE / FEP | About -200°C (-328°F) | Cryogenic seals, liners, valve seats | Creeps; PTFE is not melt processable |
| Silicone rubber (thermoset) | About -55°C (-67°F); special grades lower | Freezer gaskets, cold seals, bakeware | Not a thermoplastic resin |
| GPPS, acrylic, unmodified rigid PVC, PVDF homopolymer (poor) | GPPS and acrylic brittle at any temperature; rigid PVC near freezing; PVDF homopolymer about 5 to -15°C (41 to 5°F) | Avoid for cold impact | Use impact-modified PVC or a PVDF copolymer for cold parts |
Approximate values for typical grades. They are guides to where impact toughness falls off, not ratings. Actual limits depend on grade, wall thickness, notches, molded-in stress and impact speed. Test parts at the lowest service temperature and check the data sheet for your grade.
The good performers
Polyethylene is the default for cold service. LDPE and LLDPE stay flexible far below freezing, which is why freezer bags and flexible lids use them. HDPE keeps good impact strength for freezer tubs, coolers and outdoor tanks, and UHMW-PE stays tough at very low temperatures. See HDPE vs. LDPE.
Impact-copolymer polypropylene is the stiffer, more heat-resistant alternative to PE. Look for notched Izod or instrumented impact at -20 or -30°C (-4 or -22°F) on the data sheet. See PP homopolymer vs. impact copolymer.
Polycarbonate stays tough unnotched to about -40°C (-40°F), but sharp corners and thick sections let cracks start more easily as it gets colder. Siloxane copolymer grades keep notched ductility to -40°C (-40°F) or lower. PC/ABS is less notch sensitive and is common in outdoor housings. See best plastic for impact resistance.
Nylon is brittle dry and in the cold when unmodified. Impact-modified grades, especially once conditioned with some moisture, stay ductile to about -30 to -40°C (-22 to -40°F). Cable ties for cold climates are often an impact-modified nylon 66.
TPU, especially polyether types, stays flexible in the cold and is used for cable jackets, seals and casters in cold storage. PTFE and FEP work in cryogenic service down to about -200°C (-328°F). PVDF homopolymer is the exception among fluoropolymers: it turns brittle not far below freezing, so cold parts call for a PVDF copolymer grade. See fluoropolymers.
Silicone rubber is a thermoset elastomer, not a molding resin we supply, but it is the usual material for freezer and oven gaskets because it stays flexible to about -55°C (-67°F).
The poor performers
- PP homopolymer turns brittle near freezing. Many cracked freezer lids are homopolymer.
- General-purpose polystyrene and acrylic are brittle at any temperature. HIPS and impact-modified acrylic are better but still limited.
- Unmodified rigid PVC loses impact strength quickly below freezing. Pipe and fittings need extra care in cold handling; impact-modified PVC grades exist for cold use.
- Glass-filled grades start with low elongation, and cold takes away what little give they have.
Freezers, winter outdoors and cold chain
Home and food-service freezers run at about -18°C (0°F). PE, impact PP and copolyester containers handle that easily. If the container is also microwaved or dishwashed, impact PP is usually the best compromise. See best plastic for food containers.
Outdoor winter parts often see -30 to -40°C (-22 to -40°F) in Canada and the northern U.S., plus UV. Pair cold impact with UV stabilization. See best plastics for outdoor use.
Cold chain and lab storage can reach -80°C (-112°F) in ultra-low freezers and about -78°C (-109°F) on dry ice. PP and PE vials and racks are common there, but test the part, because toughness at room temperature says little about behavior that cold.
Design for shrinkage too. Plastics contract several times more than metal as they cool, so press fits around metal inserts tighten, clearances open up and snap-fits stiffen. Keep corners radiused and walls uniform.
What to send us for a quote
- The grade you run now, or the part and what it does
- The lowest temperature it sees, and whether it is hit or dropped while cold
- Upper temperature too (dishwasher, microwave, sun)
- Food contact or other compliance needs
- Quantity for this order and per year, and ship-to city
Common questions
What plastic is best for freezer use?
Polyethylene (LDPE, LLDPE, HDPE) and impact-copolymer polypropylene are the usual choices for freezer containers and lids because they stay tough at about -18°C (0°F) and well below. Polycarbonate and copolyester are used for clear freezer items.
Why does plastic crack in the cold?
As a plastic cools, its molecules lose the mobility that lets them yield and absorb energy, so a blow that would dent it at room temperature cracks it instead. The temperature where this happens varies by resin, notch and wall thickness.
Does polypropylene get brittle in the cold?
Homopolymer does: it turns brittle near 0°C (32°F). Impact copolymer, which carries a rubber phase, stays tough to about -20 to -40°C (-4 to -40°F) depending on the grade, so it is the grade to use for freezer and winter parts.
Is polycarbonate good in cold weather?
Yes in thin, well-radiused parts: unnotched polycarbonate stays tough to about -40°C (-40°F). Standard grades are notch sensitive in the cold, though, so sharp corners and thick sections can crack below freezing. Low-temperature siloxane copolymer grades help.
What plastic works at cryogenic temperatures?
PTFE and FEP are used in cryogenic service down to about -200°C (-328°F), and UHMW-PE also keeps useful toughness far below freezing. Most other thermoplastics are brittle at those temperatures, so test the actual part.
Is acrylic OK in the cold?
Acrylic is brittle at room temperature and does not get better in the cold, so it cracks easily if knocked in winter. Use polycarbonate or impact-modified acrylic for clear parts that may be hit in the cold.
What is the glass transition temperature and why does it matter in the cold?
Tg is where the amorphous part of a polymer changes from glassy to rubbery. Rubber-toughened and semi-crystalline resins with a low Tg in the amorphous phase, such as polyethylene and impact PP, stay tough in the cold; glassy resins with no rubber phase, such as polystyrene and acrylic, are brittle at any normal temperature.
Tell us how cold the part gets
A polymer chemist reviews every request, then matches your grade or finds a qualified equivalent and prices it.
What to send for an accurate quote
- The grade name, from any supplier, or a data sheet
- Color (natural, black or a custom match)
- Fill type and percentage, if any
- Melt flow, if you know it
- Quantity for this order and what you use in a year
- Ship-to city and state or province