LOW TEMPERATURE DEFORMATION AND STRENGTH OF POLYIMIDE FILMS DUE TO THICKNESS AND DEFORMATION SPEED

Abstract

In work mechanical properties of polyimide films analogue kapton H (manufactures of the People's Republic of China) with different thickness in the temperature interval 77-293 K and deformation speed interval 10-4-10-3 s-1 are carried out. It is established, that the films are in a forced elastic state at both temperatures of deformation. Contributions to total deformation such as elastic, high elastic (reversible at temperature of test and delay) and irreversible components are determined. It is detected, that relaxation processes which are connected with the contribution of elastic delayed deformation and are accompanied with reduction of their length, take course at exposure at a room temperature of samples after destruction or preliminary deformation. Full removal high elastic delayed deformation occurs after heat treatment at 623 K. Sensitivity of a limit of forced elasticity sв and the contribution of elastic deformation which is reversible at test temperature to deformation speed are established. Influence of the scale factor (thickness of a film) on the mechanical characteristics, which are amplified with downturn of temperature is registered.

Keywords

• polyimides
• limit of forced elasticity
• ultimate strength
• deformability