PBT
Polybutylene Terephthalate
Glass Transition (Tg)
40–50 °C
Melting Point (Tm)
220–225 °C
Density
1.30–1.32 g/cm³
CAS Number
24968-12-5
Recycling Code
♺ 7
Category
Engineering
Repeat Unit
–[O–(CH₂)₄–O–CO–C₆H₄–CO]ₙ–
The repeating unit is the smallest structural fragment whose repetition builds the whole chain. Subscripts show the relative share of each unit in copolymers.
Key Properties
Crystallises much faster than PET, enabling short injection cycles; excellent electrical properties and dimensional stability.
Applications
Automotive connectors, ignition components, keyboard keycaps, housings.