PI
Polyimide (Kapton)
Glass Transition (Tg)
360–410 °C
Melting Point (Tm)
— (decomposes)
Density
1.42 g/cm³
CAS Number
25036-53-7
Recycling Code
♺ 7
Category
High-Performance
Repeat Unit
–[N(CO)₂–C₆H₂–(CO)₂N–C₆H₄–O–C₆H₄]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
One of the most thermally stable organic polymers; usable from −269 °C to +400 °C; typically thermoset and processed via a poly(amic acid) precursor.
Applications
Flexible printed circuits, spacecraft thermal blankets, wire insulation.