Anisotropy in the thermal shrinkage of polyimide film

✍ Scribed by Taigyoo Park; David A. Dillard; Thomas C. Ward

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 178 KB
• Volume: 38
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/1099-0488(20001215)38:24<3222::aid-polb30>3.0.co;2-d

✦ Synopsis

Anisotropy in a polyimide film was investigated in a quantitative manner by a nonlinear regression of the thermal shrinkage data obtained from thermomechanical analysis. The thermally induced shrinkage of this pyromellitic dianhydride-oxydianiline polyimide film at 573 K was directionally anisotropic in the film plane by as much as about 0.4%. The direction of maximum thermal shrinkage was inclined by about /6 rad from the machine direction of the film. The thermal shrinkage behavior of the polyimide films in the vicinity of the glass-transition temperature (T g ) showed an unusual anisotropic response. On the basis of a correlation between the anisotropy in the thermal shrinkage of the films and the molecular orientation of the polyimide, this characteristic thermal shrinkage behavior around T g is suggested to be due to a recovery of the free volume lost by a physical aging process.