Properties of oriented polyimide films prepared by different methods

A comparative study had been made of the elasticity, birefringence, shrinkage and other properties of polyimide (PI) films prepared by thermal drawing at the prepolymer (polyamic acid) stage and the PI stage. At the PI stage slight stretching of the films was accompanied by a very significant increa...

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Bibliographic Details
Published in:Polymer science USSR 1990, Vol.32 (2), p.267-271
Main Authors: Smirnova, V.Ye, Bessonov, M.I., Sklizkova, V.P.
Format: Article
Language:English
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Summary:A comparative study had been made of the elasticity, birefringence, shrinkage and other properties of polyimide (PI) films prepared by thermal drawing at the prepolymer (polyamic acid) stage and the PI stage. At the PI stage slight stretching of the films was accompanied by a very significant increase in orientation of the molecules in the direction of the drawing axis, the increase being proportional to rigidity of the PI macromolecules. When drawing took place at the polyamic acid stage the chemical structure was the determining factor, influencing orientation of the films: complete disorientation in the process of thermal cyclization was observed for the stretched flexible PI films, while in the case of the rigid PIs the degree of orientation was higher than for the same draw ratio for the films at the PI stage in the case of either thermal or chemical cyclization processes.
ISSN:0032-3950
1878-268X
DOI:10.1016/0032-3950(90)90014-W