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 s в 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.

The temperature dependence of the creep rate jump in single crystals of cadmium and zink during temperature increment is studied in the range of 1.5 to 80 K. Also studied is the creep jump behaviour δϵNS during the N–S transition in pure lead, in alloys with abnormal heat conductivity, as well as lead alloys with paramagnetic admixture of nickel. It is shown that the observed peculiarities of the low temperature creep of metals are at sharp variance with the local thermal heating hypothesis. Experimental data obtained agree satisfactorily with the quantum theory of low temperature plastic deformation.

No abstract

A first-time presentation of a wide range of charts imaging the stretch of amorphous polyimide (PI) film samples in the 300–1.6 K temperature range and an analysis of how temperature affects the conditional limit of fluidity, strength, and deformation of this film at the indicated temperatures. The athermal character of the breaking stress below the temperature of liquid nitrogen and its thermally activated behavior above 80 K are demonstrated. We also analyze the features of the behavior of glassy PI film samples that are stretched at low temperatures and then unloaded and warmed up to room temperatures.

X-ray diffractometry is used to study samples of type PM-A group B polyimide (Kapton H) subjected to uniaxial tension at room temperature and cooling to liquid nitrogen and helium temperatures. An asymmetry in the halo of the diffraction pattern from the amorphous sample is observed as a result of deformation and cooling of the samples. Deformation and cooling are found to have different effects on the intensity distribution. Thus, deformation produces “stretched” regions, while cooling produces “compressed” regions. An analysis of the diffraction patterns shows that uniaxial tension leads to partial ordering of the polyimide molecules in a sample along the direction of the applied load. The observed changes in the structure during cooling of films may indicate that mutual ordering of some of the molecules relative to one another is taking place.