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

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Background

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.

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 @1kHz	3.2
Dielectric strength ( kV.mm^-1 )	20
Dissipation factor @ 1kHz	0.002
Volume resistivity ( Ohm.cm )	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 ( g.cm^-3 )	1.31
Limiting oxygen index ( % )	25
Water absorption - over 24 hours ( % )	0.1
Thermal Properties
Heat-deflection temperature - 0.45MPa (°C )	150
Heat-deflection temperature - 1.8MPa (°C )	60
Upper working temperature (°C )	120-?
Properties Polybutylene Terephthalate Monofilament
Property		Value
Density	g.cm^-3	1.31
Extension to break	%	26
Shrinkage @100°C	%	3
Tensile strength	GPa	0.5

Applications

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

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