General Description : Normally infusible, coloured (often amber) high performance polymers with predominantly aromatic molecules of high thermal stability. Semi-fabricated shapes are usually supplied by the polymer manufacturer and made by powder sintering or working with more tractable pre-cursors and completing polymerisation in final form, though some melt-processable grades of resin are manufactured. They have excellent high temperature properties and radiation resistance, inherently low flammability and smoke emission, low creep and high wear resistance and are very expensive. They have moderately high water absorption and are prone to hydrolysis and attack by alkalis and concentrated acids.

A widely used form is Kapton® film, made in thicknesses from 0.008 to 0.125mm and which is a transparent amber colour. Thicker polyimide items are usually opaque. A range of Kapton film variants are also available. In each of these, a large measure of Kapton's basic properties are combined with an extra attribute eg increased electrical or thermal conductivity, improved corona resistance, opacity and thermoplasticity.

Films are used for capacitators, insulation, printed circuit boards and in aerospace; other applications include engine components, bearings and mechanical parts exposed to radiation.

Explanation of Kapton grade descriptions

HN Regular Kapton - Transparent Amber
CB Opaque black version of HN
MT Aluminium oxide filled, increased thermal conductivity, opaque yellow
MTB Opaque black version of MT
CR Improved corona resistance - translucent yellow
XC Electrically (semi-)conductive - opaque black
KJ Thermoplastic - transparent yellow