Polybuthyleneterephtalate is a semi-crystalline polyester. It is an
engineering plastic with high stiffness and strength with a very low
moisture absorption (an important difference with polyamides).
It is often applied in glass fiber filled compounds to gain a much higher
stiffness and strength. Due to the excellent electrical insulating properties,
also in wet conditions, it is mainly applied in electronics.
PBT has a good chemical resistance and a good long term high
temperature stability, important for electronics and automotive
applications. Many flame retardant grades are available (UL-V0).

Specific properties
Density: 1.30 g/cm3. (Higher for glass filled PBT).

Mechanical properties: Young´s Modulus ca 2.7 GPa and strength ca. 55 MPa,
both much higher in glass filled compounds. Low coefficient of friction
and high wear resistance. Good fatigue resistance.

Thermal properties: Tg around 50-60 °C, Tm ca. 225 °C.
Good resistance against continuous use at high temperatures.

Chemical resistance: very good resistance against many organic solvents,
oils and greases, and weak acids. Is attacked by strong acids and bases.

White opaque with glossy surface. Can be coloured in any colour.

Easily injection moulded and extruded. Needs to be dried very well to
prevent degradation. Due to the crystallinity the shrinkage is around 2%.

- Electronics: connectors, switches, coils, bobbins, capacitors,
relays, circuit breakers.
- Automotive sector: electronic connectors, door handles,
windscreen wipers, headlamp units.
- Consumer products: oven knobs, handles, housings (iron),
lighting fixtures.
- Industry: gears, pump housings, impellers, fan blades.

Polybutylene terephthalate

Young's modulus 2650 MPa
Shear modulus 900 MPa
Tensile strength 50 MPa
Bending strength 105 MPa
Hardness 80.5 Shore
Impact strength 0.5 J/cm
Yield strength 107.5 MPa
Thermal expansion 60 E-6/K
Thermal conductivity 0.25 W/m*K
Specific heat 1000 J/kg*K
Glass temperature 60 °C
Minimum service temperature -30 °C
Maximum service temperature 120 °C
Density 1300 kg/m3
Resistivity 1E+20 Ohm*mm2/m
Breakdown potential 42 kV/mm
Dielectric loss factor 0.011
Friction coefficient 0.23
Refraction index 1.55
Shrinkage 1.4 %
Water absorption 0.55 %