|Line diagram of the linear polyimide monomer|
|Young's modulus(E)||3200 MPa|
|Tensile strength(t)||75-90 MPa|
|Elongation @ break||4-8%|
|notch test||4-8 kJ/m|
|Vicat B||220(?) °C|
|heat transfer coefficient ()||0.52 W/m.K|
|linear expansion coefficient ()||5.5 10-5 /K|
|Specific heat (c)||1.15 kJ/kg.K|
|Water absorption (ASTM)||0.32|
|Dielectric constant (Dk) at 1MHz||3.5|
There are two general types of polyimides. One type, so-called linear polyimides, are made by combining imides into long chains. Aromatic heterocyclic polyimides are the other usual kind, where R′ and R″ are two carbon atoms of an aromatic ring. Examples of polyimide films include Apical, Kapton and Kaptrex. Polyimide parts and shapes include Meldin, Vespel and Plavis. Polyimides have been in mass production since 1955.
Polyimide is often used in the electronics industry for flexible cables and as an insulating film on magnet wire. For example, in a laptop computer, the cable that connects the main logic board to the display (which must flex every time the laptop is opened or closed) is often a polyimide base with copper conductors. The semiconductor industry uses polyimide as a high-temperature adhesive.
- Deformation temperature at 10kN needle load, source: A.K. vam der Vegt & L.E. Govaert, Polymeren,van keten tot kunstof, ISBN 90-407-2388-5
See also: Polyamide