POLYIMIDE

'Polyimide'
Line diagram of the linear polyimide monomer
Density	1430 kg/m3
Young's modulus(E)	3200 MPa
Tensile strength(t)	75-90 MPa
Elongation @ break	4-8%
notch test	4-8 kJ/m
Glass temperature	>400C
melting point	none
Vicat B	220(?) °C[1]
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

'Polyimide' (sometimes abbreviated 'PI') is a polymer of imide monomers. The structure of imide is as shown below.
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 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.

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Notes

1. 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

Links

★ Kaptrex Polyimide Film and Data Sheet

★ http://www.p84.com P84 Polyimide Fibres for High Temperature Filtration

★ Vespel Polyimide Overview

★ Meldin® Polyimide Data Sheet

★ Polyimide Microbore Tubing
''See also: Polyamide''