PBT is a strong, hard and also a stable engineering polymer widely used for electrical applications as an insulator. Part of the Polyester thermoplastics family
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- High thermal stability
- Great stiffness and hardness
- Excellent for applications requiring anti-friction properties and abrasion resistance
- Resistant to environmental stress cracking
- Great dimensional stability
- High strength
- Low water absorption
- Good weathering performance
- High Continuous service temperature – up to 150°C
- Excellent resistance to Creep
Resistant to oils, grease, alcohols, fuel, ethers, weak acids and alkaline solutions.
Not resistant to benzene, alkalis, strong acids, alkaline solutions and ketones.
Automotive; there has been much growth in automotive electronics in recent years and PBT is a popular choice for many of these parts. Under bonnet parts, sensors, ignition systems and also exterior parts e.g. mirror housings.
Electrical and electronic parts such as bobbins, connectors, sockets, switches, circuit breakers, meter housings, appliance housings and light fittings
Can be used in yarn and fibre as a coating
PBT is a semi-crystalline polymer used mainly for injection moulding in engineering applications.
When PET was introduced its melt processing temperature was beyond the range of most injection moulding machines at that time and PBT was introduced as a thermoplastic with many of the properties of PET but had a lower processing temperature.
PBT can match the mechanical properties of PET, particularly when reinforced with glass fibre.
PBT is well suited to thin wall mouldings.
Some PBT grades have rapid crystallisation allowing fast cycle times.
Flame retardant and will extinguish outside the flame. Gives off a bright yellow/orange flame with a sweet smell.
Density –1.3 g/cm ³
Pre-Drying – 4 hours at 120°C in a dehumidifying hot air drier
Melt temperature – 250-260°C
Mould Temperature – 60-80°C
Shrinkage – Depends heavily on mould temperature. The hotter the mould, the higher the shrinkage 1.4-2.0 %. In the case of 30% glass filled PBT only 0.4-0.6%
Trade Names And Manufacturers
Crastin – DuPont
Pocan – Lanxess
Ultradur – BASF
Lupox – LG Chem
Valox – Sabic IP
Ramster – Polyram
Hardie Polymers can help source grades from all of the above manufacturers
Fibre forming Polyesters were first produced in 1932 by Carothers and Hill of DuPont, with the first PBT fibres produced 10 years later in 1942. PBT compounds for moulding were launched in the 1970’s and as demand grew with new applications being found, so the number of producers also steadily increased.
More about PBT
Articles by Dr Charlie Geddes
Our longstanding partnerships allow us to specialise in sourcing and compounding most grades of engineering polymers. All brand names listed are trademarks of the manufacturers and we are not an authorised distributor for these manufacturers. We only supply prime grades in original packaging with the manufacturers documentation.
® – Trademarks owned or used by the producers.
™ – Registered in the U.S. Patent and Trademark Office (status in the U.S. only, registration status in other geographies may be different)