Polyimides from 2,3,3′,4′-biphenyltetracarboxylic dianhydride and aromatic diamines |
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Authors: | PM Hergenrother KA Watson JG Smith JrJW Connell R Yokota |
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Affiliation: | a NASA-Langley Research Center, 6A W. Taylor Street Mail Stop 226, 23681-0001 Hampton, VA, USA b Institute of Space and Astronautical Science, Sagamihara, Japan |
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Abstract: | A series of new polyimides were prepared from the reaction of 2,3,3′,4′-biphenyltetracarboxylic dianhydride (a-BPDA) with various aromatic diamines. The properties of the a-BPDA polyimides were compared with those of polyimides prepared from the reaction of 3,3′,4,4′-biphenyltetracarboxylic dianhydride (s-BPDA) with the same aromatic diamines. Films of the a-BPDA polyimides had higher glass transition temperatures (Tgs) and less color than the corresponding s-BPDA polyimide films. Light transmission at 500 nm, solar absorptivity, and thermal emissivity were determined on certain films. Films of similar polyimides based upon a-BPDA and s-BPDA containing meta linkages and others containing para linkages were each cured at 250, 300, and 350 °C. The films were characterized primarily by Tg, color, optical transparency, tensile properties, dynamic mechanical thermal analysis, and coefficient of thermal expansion. The a-BPDA meta linked polyimide films had tensile strengths and moduli higher than films of the a-BPDA para linked polyimide. The same phenomenon was not observed for the s-BPDA meta and para linked polyimides. The chemistry, mechanical, and physical properties of the polymers and films are discussed. |
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Keywords: | Polyimides Low color thin films Structure property relationship |
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