Polybutylene terephthalate (PBT)

Materials › Polybutylene terephthalate (PBT)

The engineering plastic of electrical equipment: connectors, contact carriers, housings. PBT generally absorbs less moisture than the polyamides and has good dimensional stability. Dimensional changes still depend on the grade, the reinforcement, the moulding conditions and the service environment. For hot water and prolonged damp environments, the hydrolysis resistance of the chosen grade has to be assessed.

It is prone to hydrolysis: in hot water or steam above 60 °C it ages quickly, and such duty calls for specific grades. It is also notch-sensitive, so sharp corners and undercuts must be radiused.

Each row is the median of a selection of manufacturers’ datasheets held in our archive, with the property, the standard and the number of grades stated next to the value. These figures describe the sample: they serve to compare the levels with one another, not to size a part, and they are not a guaranteed material specification. For that you need the datasheet of the chosen grade, which we supply on request.

Where a level shows no value, the documented sample was not sufficient: we prefer to remove the figure rather than publish one that does not hold. HDT and impact strength are deliberately absent, because datasheets often do not state the test condition — whether HDT is at 1.8 or 0.45 MPa, whether the impact specimen is notched — and values collected under different conditions cannot be compared.