Tritan™ to polysulfone — when repeated hot water and washing cause cracking
Baby bottles · reusable bottles · water purifier parts · coffee machines and equipment · tableware
Tritan™ has a heat deflection temperature of 85°C (1.8 MPa). Boiling water, dishwashers and repeated sterilisation approach or exceed that limit, so cracking and discolouration appear in repeated service even where room-temperature strength is ample. For food and beverage contact parts the answer is PPSU (BASF Ultrason® P) — heat deflection temperature 197°C, made without BPA or BPS.
Tritan™ became the standard for baby bottles and reusable bottles because it uses no bisphenol and is tough at room temperature. Temperature is where it runs out. With a heat deflection temperature of 85°C (1.8 MPa) and 99°C (0.455 MPa), it has almost no margin against real service conditions — boiling water poured in, dishwashers and steam sterilisers run again and again. Add coffee constituents and alkaline detergents and environmental stress cracking progresses, so a product that was fine for the first few cycles cracks and discolours after tens or hundreds.
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
What you see in the field
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.
Why this happens
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.
After contact with detergents, coffee or fats, countless fine lines appear on the surface and clarity drops to a milky haze. This is the stage immediately before cracking.
Why this happens
Where residual stress remains at the surface, contact with certain chemicals triggers dense micro-cracking (crazing). These micro-cracks scatter light, which reads as whitening, and eventually link up into through-cracks. Both copolyesters and PC show this with detergents and alkalis.
Relevant property limit
Copolyesters and PC have limited chemical resistance to detergents and alkalis
Recommended material
PPSU for food contact. The higher the cleaning and sterilisation frequency, the greater the advantage of sulfones.
After hot water, a dishwasher cycle or a microwave, parts warp — assembly dimensions no longer fit, or seals begin to leak.
Why this happens
The simplest cause: service temperature has exceeded the material's heat deflection temperature. Dishwasher interiors exceed 70°C and rinse stages go higher, while PETG has an HDT of only 64°C (1.8 MPa) — immediately in the danger zone. Tritan™, at 85°C, has no margin against boiling water either.
Relevant property limit
PETG HDT 64°C · Tritan™ HDT 85°C (1.8 MPa)
Recommended material
Sulfones for constant hot-water or dishwasher exposure; PPSU for food contact.
Odour or taste transfers and the surface turns tacky
What you see in the field
Coffee, fats or detergent constituents soak in and leave an odour, or the surface loses gloss and feels tacky. Washing does not restore it.
Why this happens
When a material is not sufficiently rigid at service temperature, the surface softens slightly and constituents are absorbed and retained. The closer the service temperature is to the material's heat deflection temperature, the worse it gets. Sulfones have a far larger margin between service temperature and HDT, so this is much less common.
Relevant property limit
Occurs when service temperature approaches the material's HDT
One point to be clear about — room-temperature notched impact strength is higher for Tritan™ (93 kJ/m², ISO 180) than for PPSU (58 kJ/m²). The change is not made because PPSU is better in every respect. It is made for one reason: holding properties through repeated high-temperature, chemically aggressive service.
Where each sits on heat
60°C Hot water · coffee brewing70°C Dishwasher100°C Boiling water · steam121°C Autoclave 121°C134°C Autoclave 134°C
PETG
64°C
Tritan™
85°C
PC
125°C
PSU
175°C
PPSU
197°C
PESU
205°C
Based on heat deflection temperature (HDT/A, 1.8 MPa). PETG and Tritan™ are to ASTM D648, PC and the sulfones to ISO 75, so specimens and conditions differ and absolute comparison may be imprecise — read this as a family-level ranking. HDT is also a short-term deflection temperature under load, so continuous service temperature must be set lower.
Property comparison
Figures are from the manufacturers’ published datasheets, with test methods stated.
Tritan™ copolyester against the sulfone family
Property · test method
TritanEastman Tritan™ TX1001
PPSUBASF Ultrason® P 3010
Feedstock bisphenol
No bisphenol
No bisphenol
Heat deflection temp. HDT/A
85 °CASTM D648 · 1.82 MPa
197 °CISO 75-1/-2 · HDT/A · 1.8 MPa
Heat deflection temp. HDT/B
99 °CASTM D648 · 0.455 MPa
—
Glass transition temp. Tg
—
220 °CISO 11357-1/-2 · DSC · 10°C/min
Notched impact (Izod)
93 kJ/m²ISO 180 · 23°C · notched
58 kJ/m²ISO 180/A · 23°C · notched
Notched impact (Charpy)
—
70 kJ/m²ISO 179/1eA · 23°C · notched
Tensile strength
43 MPaISO 527 · 항복
74 MPaISO 527-1/-2 · 항복 · 50 mm/min
Tensile modulus
1548 MPaISO 527
—
Light transmittance
90 %ASTM D1003 · 전광선 투과율
—
Density · specific gravity
1.18 g/cm³ASTM D792 · 비중
—
Flammability UL 94
—
V-01.5 mm
Melt temperature
260–282 °C가공 용융온도
—
Mould temperature
38–66 °C금형온도
—
PETG and Tritan™ figures are to ASTM, PC and BASF Ultrason® figures to ISO (PC to ISO 75-2). Specimen geometry and test conditions differ, so the columns cannot be compared one to one. The table is for judging whether materials sit in the same class; where precise comparison matters, request data measured to a common standard. Note also that Izod (ISO 180) and Charpy (ISO 179) are different tests — compare only like with like.
Tritan — Glass transition temperature is not stated in this TDS. Judge heat performance from the heat deflection temperature.
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
Bottles, cups, coffee equipment and tableware are all food and beverage contact, so PPSU is the only option. PSU is BPA-based and PESU is BPS-based, both subject to food-contact recertification under EU Regulation 2024/3190.
PPSU · 폴리페닐설폰
No bisphenol
BASF Ultrason® P 3010
HDT/A
197
Tg
220
Notched impact
70
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).
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.
Real conversion cases
These are the conversion reasons we actually receive. All three passed room-temperature testing and failed in service.
01
Baby bottles · water purifier parts · coffee equipment
Consumer goods · food & beverage
Tritan™→PPSU
Symptom
Cracking and discolouration after repeated use
Repeated exposure to hot water, the chemical constituents of coffee, cleaning agents and dishwasher cycles produced cracking and colour change. In every case the parts were fine at first and failed once the use count built up.
Cause
85°C heat deflection ceiling plus environmental stress cracking under repeated heat and detergent
Why
Food and beverage contact, so PPSU only. Its heat deflection temperature of 197°C leaves a wide margin over hot-water and dishwasher temperatures, and it is made without BPA or BPS.
Conversion procedure
1
Put the service conditions into numbers
Tell us maximum contact temperature, cycle count, cleaning and sterilisation method (dishwasher, steam, autoclave), and contact media (hot water, coffee, fats, detergents). These four determine grade selection.
2
Confirm the real thing with an evaluation sample
We send Ultrason® P 3010 samples. It is worth confirming the colour cast (a slight honey tint) and surface finish with your own eyes first.
3
Run a trial shot in existing tooling
BASF states that existing injection moulds for PESU can continue to be used. Processing conditions differ substantially, though — sulfones are typically processed above 340°C and pre-drying is mandatory. We support the condition set-up.
4
Test repeatedly under real service conditions
Cycle hot water, washing and sterilisation beyond the real cycle count and check for cracking, discolouration and dimensional change. A room-temperature drop test cannot verify the purpose of this change.
5
Secure the certification documents
We supply food-contact approvals and material certificates, and confirm which documents your export markets require.
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
What temperature can Tritan™ withstand?
Eastman Tritan™ TX1001 has a heat deflection temperature of 85°C at 1.82 MPa and 99°C at 0.455 MPa (ASTM D648). These are short-term deflection temperatures under load, so continuous service temperature must be set lower. Boiling water at 100°C and steam sterilisation exceed this range.
I was told it was dishwasher-safe. Why does it crack?
Dishwasher interiors exceed 70°C and go higher during the rinse stage, with alkaline detergent acting at the same time. Even where a single cycle passes, repeated heat and chemistry relax moulded-in residual stress and environmental stress cracking progresses. That is why parts are fine at first and crack after tens or hundreds of cycles.
What high-temperature transparent material can replace Tritan™?
For food and beverage contact, PPSU (polyphenylsulfone, BASF Ultrason® P). Heat deflection temperature 197°C and glass transition temperature 220°C, it withstands repeated steam sterilisation and is made without BPA or BPS, answering EU food-contact regulation. It is not colourless, however — it carries a slight honey tint.
Is PPSU stronger than Tritan™ in every respect?
No. Room-temperature notched Izod impact strength is 93 kJ/m² for Tritan™ TX1001 against 58 kJ/m² for PPSU P 3010 (ISO 180, 23°C), so Tritan™ is higher. PPSU's advantage is not room-temperature impact but retention of properties at temperature and durability under repeated sterilisation and detergent exposure.
Can it be used for baby bottles if it is not water-clear?
PPSU is transparent but carries a slight honey tint. Many PPSU baby bottles on the market simply show that colour. Where completely colourless transparency is essential, PPSU is not suitable and the heat requirement needs to be revisited.
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.
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.
