PETG to polysulfone — the 64°C heat deflection limit
Transparent containers · display parts · medical disposables · household goods
PETG has a heat deflection temperature of 64°C (1.8 MPa) and a glass transition temperature of 80°C. It is the lowest-heat family among transparent materials, so warping and cracking are hard to avoid under hot water, dishwashing and sterilisation. Where high-temperature exposure is constant, move up to the sulfone family; for food and beverage contact the answer is PPSU.
PETG moulds well, is transparent and uses no bisphenol, which is why it is widely used for transparent containers and disposables. Its heat resistance is low. Heat deflection temperature is 64°C at 1.8 MPa and only 70°C at 0.455 MPa, with a glass transition temperature of 80°C. Dishwasher interiors exceed 70°C and hot water and coffee brewing run hotter still. PETG simply has no margin where high-temperature exposure is expected.
Are you seeing this?
You do not need to have identified the cause. Select what you see on the floor and we will show the mechanism and the material that answers it.
It cracks and splits after repeated use
Cracks start where stress concentrates — handles, threaded areas, around the gate — and grow with each cycle until the part fails. Typically fine for the first few uses, then failing after tens or hundreds of cycles.
As service temperature approaches the material's heat deflection temperature, moulded-in residual stress relaxes and deformation accumulates. Add detergents or food constituents and environmental stress cracking (ESC) sets in, so parts that passed short-term testing break in repeated service. High room-temperature impact strength does not prevent this — it is a temperature and chemistry problem.
Tritan™ HDT 85°C · PETG HDT 64°C · PC HDT 125°C (1.8 MPa)
PPSU for food and beverage contact. PSU or PPSU for medical and non-food.
Stated plainly
PETG's problem is a simple one — temperature, not chemical degradation or regulation. It is perfectly usable at room temperature, so if the service environment stays there, there is no reason to change. A switch is only worthwhile where high-temperature exposure is constant. For reference, PETG's notched Izod impact strength is 6.2 kJ/m² (ISO 180), which is not high — its toughness sits in a similar class to PSU (Charpy 5.5 kJ/m²).
Where each sits on heat
Property comparison
Figures are from the manufacturers’ published datasheets, with test methods stated.
| Property · test method | PETGEastman Eastar™ 6763 | PSUBASF Ultrason® S 2010 | PPSUBASF Ultrason® P 3010 |
|---|---|---|---|
| Feedstock bisphenol | No bisphenol | BPA-based | No bisphenol |
| Heat deflection temp. HDT/A | 64 °CASTM D648 · 1.82 MPa | 175 °CISO 75-1/-2 · HDT/A · 1.8 MPa | 197 °CISO 75-1/-2 · HDT/A · 1.8 MPa |
| Heat deflection temp. HDT/B | 70 °CASTM D648 · 0.455 MPa | — | — |
| Glass transition temp. Tg | 80 °CDSC | 187 °CISO 11357-1/-2 · DSC · 10°C/min | 220 °CISO 11357-1/-2 · DSC · 10°C/min |
| Notched impact (Izod) | 6.2 kJ/m²ISO 180 · 23°C · Type A notch | — | 58 kJ/m²ISO 180/A · 23°C · notched |
| Notched impact (Charpy) | — | 5.5 kJ/m²ISO 179/1eA · 23°C · notched | 70 kJ/m²ISO 179/1eA · 23°C · notched |
| Tensile strength | 50 MPaISO 527 · 항복 | 75 MPaISO 527-1/-2 · 항복 · 50 mm/min | 74 MPaISO 527-1/-2 · 항복 · 50 mm/min |
| Tensile modulus | 2100 MPaISO 527 | 2550 MPaISO 527-1/-2 | — |
| Light transmittance | 91 %ASTM D1003 modified · 필름 250 µm | 89 %DIN 5036-3 · 2 mm | — |
| Density · specific gravity | 1.27 g/cm³ISO 1183 | 1.23 g/cm³ISO 1183 | — |
| Water absorption (saturation) | — | 0.8 %ISO 62 · 수중 포화 · 23°C | — |
| Flammability UL 94 | — | HB (1.5 mm) · V-2 (3.2 mm) | V-01.5 mm |
| Melt temperature | 249–271 °C가공 용융온도 | — | — |
| Mould temperature | 16–38 °C금형온도 | — | — |
PETG — The TDS carries no optical data for injection-moulded parts. The transmittance above is for 250 µm film and cannot be compared directly with mouldings of a different thickness.
PSU — The lowest notched impact strength of the three sulfones (5.5 kJ/m²). If a part used PC for toughness, PSU is a step back rather than a replacement — look at PPSU instead.
PPSU — The only sulfone made without BPA or BPS, and therefore the family that answers EU food-contact regulation. Notched impact strength of 70 kJ/m² puts it on par with PC (75).
The material that answers it
PPSU for food and beverage contact. For non-food use, PSU or PESU are also candidates — PESU (HDT 205°C) where more thermal headroom is wanted.
PPSU · 폴리페닐설폰
No bisphenolBASF Ultrason® P 3010
The only sulfone made without BPA or BPS, and therefore the family that answers EU food-contact regulation. Notched impact strength of 70 kJ/m² puts it on par with PC (75).
BASF Ultrason® P 3010 Property detail →PPSU is currently catalogued on Ultrason® P 3010. If your application needs a different PPSU grade, ask us about extending the range and we will check availability.
Conversion procedure
- 1
Establish maximum exposure temperature and duration
Momentary versus constant exposure changes the conclusion. For room-temperature applications a change may be unnecessary.
- 2
Confirm whether it is food contact
Food and beverage contact means PPSU only; non-food widens the choice to PSU and PESU.
- 3
Review the processing gap
PETG is processed at 249–271°C where sulfones are typically above 340°C. Check your equipment's temperature ceiling and whether you have drying capability.
- 4
Trial-shoot with an evaluation sample
Samples are supplied and we support the processing set-up.
- 5
Verify repeatedly at real service temperature
Check warping and dimensional change at the actual service temperature and cycle count.
Before you switch
On room-temperature impact alone, Tritan™ is higher
Notched Izod impact strength (ISO 180, 23°C) is 93 kJ/m² for Tritan™ TX1001 against 58 kJ/m² for PPSU P 3010. For drop impact at room temperature, Tritan™ is the stronger material. The reason to change is not room-temperature toughness but the 85°C heat deflection ceiling and environmental stress cracking under repeated heat and detergent exposure. Select on room-temperature testing alone and the part will fail again in service.
PSU has far lower notched impact strength than PC
Notched Charpy impact strength (ISO 179, 23°C) is 75 kJ/m² for PC against 5.5 kJ/m² for PSU S 2010 — roughly one thirteenth. Replacing a PC part that was chosen for toughness with PSU raises heat resistance but gives up impact performance. Where PC-equivalent toughness is required, PPSU (70 kJ/m²) is the only answer.
Sulfones are transparent but not colourless
Light transmittance is 89% for PSU and 88% for PESU (DIN 5036-3, 2 mm) — numerically close to PC and Tritan™ — but sulfones carry a slight honey tint. BASF's own material comparison describes the optical character of PESU and PPSU as a slight honey tint. Where water-clear colourlessness is an absolute requirement, sulfones are not the answer.
Processing conditions are completely different
Tritan™ is processed at a melt temperature of 260–282°C and PETG at 249–271°C, whereas sulfones are typically processed above 340°C with much higher mould temperatures. They are also moisture-sensitive, so pre-drying is mandatory. Carrying over existing conditions produces short shots, splay and thermal degradation. Plan a processing-condition reset as part of the switch.
Cost goes up
Sulfones are super engineering plastics with a higher raw-material cost than PC or copolyesters. The right basis for comparison, however, is not price per kilogram but the cost of rejects, claims and remakes over the product's life. If cracking is already driving returns on a repeatedly used product, a total-cost view is the accurate one.
Frequently asked questions
Tell us the service conditions and we will narrow the grade
Maximum contact temperature, cycle count, cleaning and sterilisation method, contact media — those four identify the candidates. Evaluation samples are available.
Coming from another material
From Tritan™ copolyester →
Baby bottles · reusable bottles · water purifier parts · coffee machines and equipment · tableware
From PC · polycarbonate →
Ultrasound probe housings · dental instruments · reusable medical devices · food-contact containers · catering trays
EU bisphenol restriction guide →
Regulation 2024/3190 · food-contact recertification
Tritan™ and Eastar™ are trademarks of Eastman Chemical Company, INFINO® of Lotte Chemical, and Ultrason® of BASF SE. Competitor product names are used solely for factual identification and comparison, and do not imply affiliation or endorsement.