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Polybutylene Terephthalate (PBT) - Properties and Applications - Supplier Data by Goodfellow


Polybutylene Terephthalate (PBT) is a semi-crystalline, white or off-white polyester similar in both composition and properties to polyethylene terephthalate (PET).

It has somewhat lower strength and stiffness than polyethylene terephthalate, PET, is a little softer but has higher impact strength and very similar chemical resistance. As Polybutylene Terephthalate (PBT) crystallises more rapidly than PET, it tends to be preferred for industrial scale moulding.


Applications of Polybutylene Terephthalate (PBT) include electrical and automotive components (including “under-bonnet”) and power tool casings.

Key Properties

The key properties of Polybutylene Terephthalate ( PBT ) are tabulated below.

Table 1. Key properties

Chemical Resistance
Acids - dilute Good
Alcohols Good
Alkalis Poor-Good
Aromatic hydrocarbons Good
Greases and Oils Good
Ketones Good
Electrical Properties
Dielectric constant @ 1 kHz 3.2
Dielectric strength ( ) 20
Dissipation factor @ 1 kHz 0.002
Volume resistivity ( ) 1015
Mechanical Properties
Elongation at break ( % ) 250
Hardness – Rockwell M70
Izod impact strength ( J.m-1 ) 60
Tensile modulus ( GPa ) 2
Tensile strength ( MPa ) 50
Physical Properties
Density ( ) 1.31
Limiting oxygen index ( % ) 25
Water absorption - over 24 hours ( % ) 0.1
Thermal Properties
Heat-deflection temperature - 0.45 MPa ( °C ) 150
Heat-deflection temperature - 1.8 MPa ( °C ) 60
Upper working temperature ( °C ) 120-?
Properties Polybutylene Terephthalate Monofilament
Property   Value
Density 1.31
Extension to break % 26
Shrinkage @ 100 °C % 3
Tensile strength GPa 0.5

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  1. Luc Chene Luc Chene Canada says:

    Is making toothbrush bristles from PBT a good application ? Can't Bisphenol leach from it ?

  2. aravind vatsala aravind vatsala United States says:

    Hi I am using PBT material - Clip, have breakage issue.

    • Vatsal Kapadia Vatsal Kapadia India says:

      Hello, we are facing the same issue. its a possibility of oxidation which causes breakage. Solution could be the addition of Anti-oxidants in your polymer batch along with providing better vents in the molds

  3. John Rice John Rice Ireland says:

    What's the TG of PBT

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