ANALYSIS OF THE MOISTURE CONTENT EFFECT ON THE SPECIFIC INDEX AND DAMAGE ACCUMULATION KINETICS IN THE STRUCTURE OF POLYMERIC MATERIALS DURING NATURAL CLIMATIC AGING

Abstract

We present the results analyzing the climatic resistance of epoxy polymers obtained on the basis of a modified Etal-247 resin cured by Etal-45M under the effect of natural climatic factors in a temperate continental climate. The kinetics of damage accumulation in the structure of polymer samples under tensile loads was studied on the basis of the results obtained using the author's method. The essence of the technique was to determine the coordinates of the “critical” points of deformation curves based on the time series fractal analysis methods, recorded with a high readings frequency (0.01 s). To estimate the level of accumulated failures leading to the de-struction of samples under tensile loads, we used a parameter defined as the ratio of the number of points with a fractality index less than 0.5 to the total number of points on deformation curves (until reaching the level of “critical” tensile stresses). Time intervals of 0.16 seconds were studied with analyzed area shifted with a step of 0.01 sec. A specific index is proposed that characterizes the accumulated number of damages in the polymer sample structure per unit of its strength. Its achievement leads to the destruction of the composite under study. We have determined the moisture state effect and climatic aging duration on the damage accumulation kinetics in the polymer sample structure under tensile loads.

Keywords

• climatic aging, polymers, moisture content, damage accumulation, specific index, fractal analysis