Table of Contents
Reviewed and updated by ICD - Week 43/2026
Short answer: PPSU is clearly more heat resistant than PA. PPSU has a glass transition temperature of 220 °C and a heat deflection temperature of 207 °C under a 1.82 MPa load (Solvay), and survived more than 1,000 steam cycles at 132 °C without cracking. PA6 melts at 220 °C but its heat deflection temperature under the same load is only about 60 °C (BASF). The transparent PA used for baby bottles is a special amorphous PA that softens at 145 °C, not ordinary nylon.
PA and PPSU are often placed side by side for baby bottles and medical items. In practice the two groups differ in structure: PA6 and PA66 are semi-crystalline plastics, milky and opaque; PPSU is an amorphous plastic, light amber and transparent. This article takes its figures from manufacturers’ datasheets (Solvay, BASF, EMS-Grivory, and Arkema through comparison tables), and separates “ordinary PA” from “transparent PA”, because most online arguments mix the two.
What PPSU is and how it differs from PA
PPSU (polyphenylsulfone) belongs to the sulfone family with PSU and PESU, and is the toughest of the three. According to Octud, PPSU is in the super-engineering plastic group, while PA is in the engineering plastic group below it. Radel R-5000 has a notched impact toughness of 690 J/m (Solvay), a density of 1.29 and an equilibrium water absorption of only 1.1% (IDES), while PA6 absorbs 2.6 to 3.4% (BASF Ultramid B3K).
Ordinary PA6 and PA66 are semi-crystalline plastics: PA6 melts at 220 °C and PA66 at 260 °C, but under a 1.8 MPa load the HDT is only 60 °C for PA6 and 75 °C for PA66 (unreinforced grades). With glass-fibre reinforced grades, the HDT can reach 250 °C for PA66 GF30. So the statement “PA withstands 110 to 120 °C” is only true as a continuous working temperature under light load, not as a heat deflection figure.
| Criterion | PA6, PA66 (unreinforced) | PPSU (Radel R-5000) |
|---|---|---|
| Structure | Semi-crystalline, opaque | Amorphous, transparent, light amber |
| Melting point or Tg | 220 °C (PA6), 260 °C (PA66) | Tg 220 °C |
| HDT 1.8 MPa | 60 °C (PA6), 75 °C (PA66) | 207 °C |
| Equilibrium water absorption | 2.6 to 3.4% (PA6) | 1.1% |
| Density | 1.13 g/cm³ | 1.29 g/cm³ |
| Steam sterilisation | PA66 reaches 134 °C, 50 cycles; PA6 does not (BASF) | Over 1,000 cycles at 132 °C (Solvay) |
Transparent PA: why not to compare PPSU with ordinary nylon
Baby bottles in PA are not made from PA6 or PA66. Octud describes the PA used for bottles as an amorphous transparent polyamide, designed to form almost no crystals that scatter light, for example Arkema’s Rilsan Clear. The Octud table sets two datasheets side by side by the same ISO methods: PPSU Ultrason P 3010 has a Tg of 220 °C, an HDT of 197 °C, a tensile modulus of 2,250 MPa and a notched toughness of 70 kJ/m²; transparent PA Rilsan Clear G850 has a Tg of 145 °C, an HDT of 120 °C, a modulus of 1,680 MPa and a notched toughness of 8.5 kJ/m².
That means transparent PA can still exceed the 100 °C of boiling water, but its safety margin is only 45 °C against 120 °C for PPSU. EMS-Grivory, the maker of Grilamid TR, states that its transparent PA grade withstands 121 °C steam only to a limited extent and cannot withstand 134 °C steam: the material quickly turns cloudy, brittle or warped. EMS itself also says ordinary transparent PA is not suited to repeated autoclaving, and had to develop Grilamid TR HT 200 separately (Tg 200 °C, 500 autoclave cycles at 134 °C) to fill that gap.
The rest of the usual comparison, “PA looks better because it is as clear as glass”, does not hold: PPSU is clear too, with only a light amber tint (BASF describes Ultrason P 3010 as transparent with a slight honey-yellow tone).
Impact strength and repeated use
For baby bottles and medical items, what decides is repeated heat resistance, no stress cracking, and not breaking when dropped. The Octud table gives PPSU 70 kJ/m² at 23 °C and 50 kJ/m² at -30 °C, and transparent PA 8.5 and about 8.6 to 11.4 kJ/m² in the same conditions, meaning PPSU is many times tougher when there is a scratch. In an unnotched drop test neither breaks. BASF states that Ultrason P 3010 can be used for baby bottles, food contact, 134 °C steam, dishwashers and microwaves.
On UV, no independent data was found for PPSU under UV-C disinfection lamps, so it is not claimed that PPSU can be used freely with UV. With PA, 254 nm radiation breaks the amide bond (see the article on UV and steam sterilisation of PA); this does not apply word for word to PPSU, but testing is needed if the process includes UV-C.
Why plastic pallets and crates do not use PA or PPSU
Customers of ICD Vietnam often ask why such good plastics are not used for pallets or industrial plastic crates. The answer has three technical reasons, all calculable from datasheets.
First, weight. HDPE has a density of about 0.958 g/cm³ (Borealis BB2588) and PPSU 1.29: with the same pallet mould, PPSU material is about 35% heavier, pushing the total pallet mass from 15 to 20 kg up to about 20 to 27 kg (a calculation from the two densities). Second, temperature: PPSU softens at 220 °C, and in warehouses and on trucks that range is far wider than needed. Third, price: PPSU resin is in the super-engineering plastic group; the Octud and Solvay documents do not publish prices, but using this resin to mould a 15 to 20 kg part has no economic basis when HDPE and PP already carry the load.
The job of a pallet or crate is to carry loads and withstand impact from forklift tines and drops from height, so ICD Vietnam concentrates on virgin HDPE for pallets and waste bins, and PP plastic for baskets and stackable plastic crates.
Which to choose by need
Baby bottles, items steam-sterilised repeatedly every day, or medical instruments sterilised at 121 to 134 °C: PPSU, because there is data for more than 1,000 cycles. Bottles for boiling in water where light weight is the priority: transparent PA is a sound choice, but check each maker’s datasheet. Wear-resistant technical parts, gears, wheels: PA6 or PA66, usually reinforced. Storing and transporting goods: HDPE, PP.
Frequently asked questions
Which is more heat resistant, PA or PPSU?
PPSU: Tg 220 °C, HDT 207 °C at 1.82 MPa. Ordinary PA6 and PA66 have an HDT of only 60 to 75 °C at the same load; transparent PA Rilsan Clear G850 has a Tg of 145 °C.
Is PPSU safe for food contact products?
BASF states that Ultrason P 3010 (PPSU) is approved for food contact and used for baby bottles, withstanding 134 °C steam, dishwashers and microwaves.
Are PA baby bottles made from PA6 or PA66?
No. They are a special amorphous transparent polyamide (such as Rilsan Clear or Grilamid TR), different from ordinary opaque nylon.
Can transparent PA be autoclaved at 134 °C?
Ordinary grades cannot: EMS states Grilamid TR withstands 121 °C steam to a limited extent and does not withstand 134 °C steam. Only Grilamid TR HT 200 reaches 500 cycles at 134 °C.
When should you choose PA rather than PPSU?
When you need light weight and clarity and only boiling in water, or for wear-resistant parts, gears and wheels, use reinforced PA6 or PA66.
Why are plastic pallets not made from PPSU?
PPSU is about 35% heavier than HDPE for the same volume and far more heat resistant than a warehouse needs; HDPE and PP carry the load at a reasonable cost.
Contact ICD Vietnam
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
- Solvay, Radel PPSU, Veradel PESU, Acudel PPSU Design Guide (Tg 220 °C, HDT 207 °C at 1.82 MPa, notched Izod 690 J/m, more than 1,000 steam cycles at 132 °C) - solvay.com
- IDES, Radel R-5000 technical data sheet (density 1.29; equilibrium water absorption 1.1%; shrinkage 0.70%) - catalog.ides.com
- Octud, PPSU vs PA baby bottles (comparison table of the BASF Ultrason P 3010 and Arkema Rilsan Clear G850 Rnew datasheets, same ISO test methods) - octud.com
- EMS-Grivory, Grilamid TR (amorphous transparent PA: 121 °C steam limited, 134 °C steam not withstood; good gamma and EO resistance) - relayte.co.za (EMS PDF copy)
- EMS-Grivory, Reusable instead of disposable (Grilamid TR HT 200: Tg 200 °C, 500 autoclave cycles at 134 °C; ordinary transparent PA is not usable for repeated autoclaving) - ems-group.com
- BASF, Thyseed baby bottles now made of Ultrason (PPSU Ultrason P 3010: food contact, 134 °C steam, microwave, dishwasher) - basf.com
- BASF, Ultramid B3K (PA6) Product Information, 09/2026: density 1,130 kg/m3, melting point 220 °C, saturation moisture absorption 9 to 10%, equilibrium at 23 °C/50% RH 2.6 to 3.4%, HDT A 60 °C, drying 80 °C for 4 hours - download.basf.com
- Borealis, Borstar BB2588 HDPE Product Data Sheet, 05/08/2024 (density 958 kg/m3, melting point 132 °C, Vicat 127 °C) - borealisgroup.com
