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Rigid-Rod And Segmented Rigid-Rod Polyimides: GEL/SOL And Liquid Crystalline Transitions, Fibers And Films

Published online by Cambridge University Press:  15 February 2011

Stephen Z. D. Cheng ,
Fred E. Arnold Jr. ,
Mark Eashoo ,
Song-Koo Lee ,
Steve L. C. Hsu ,
Chul Joo Lee  and
Frank W. Harris
Stephen Z. D. Cheng
Affiliation:
Institute and Department of Polymer Science, University of Akron, Akron, OH 44325–3909
Fred E. Arnold Jr.
Affiliation:
Institute and Department of Polymer Science, University of Akron, Akron, OH 44325–3909
Mark Eashoo
Affiliation:
Institute and Department of Polymer Science, University of Akron, Akron, OH 44325–3909
Song-Koo Lee
Affiliation:
Institute and Department of Polymer Science, University of Akron, Akron, OH 44325–3909
Steve L. C. Hsu
Affiliation:
Institute and Department of Polymer Science, University of Akron, Akron, OH 44325–3909
Chul Joo Lee
Affiliation:
Institute and Department of Polymer Science, University of Akron, Akron, OH 44325–3909
Frank W. Harris
Affiliation:
Institute and Department of Polymer Science, University of Akron, Akron, OH 44325–3909
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Abstract

Organo-soluble rigid-rod and segmented rigid-rod polyimides and their copolyimides exhibit isotropic solutions in hot m-cresol, but form gels upon cooling. A lyotropic liquid crystal phase is observed below the gel/sol transition. Mechanical gel formation is caused by liquid-liquid phase separation, while the liquid crystal phase may be formed through a nucleation process after gelation. High performance fibers can be spun from the hot isotropic solutions using a dry-jet wet spinning method. After the fibers are drawn at high temperatures, they display tensile strength higher than 3.2 GPa and an initial modulus higher than 130 GPa. In particular, the fibers retain relatively high mechanical properties at elevated temperatures. Solution casted films exhibit very low thermal expansion coefficients and dielectric constants. Their structure, morphology and property relationships will also be discussed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 227: Symposium J – Materials Science of High Temperature Polymers for Microelectronics , 1991 , 137
Copyright
Copyright © Materials Research Society 1991

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References

REFERENCES

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