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1. Experimental data for all of the SKD rubber-base composites filled with particles with a diameter D< 10−4 cm, which were investigated in the study, are not described over the entire interval of fillings by any of the familiar theories, and the discrepancy increases with increasing degree of filling. 2. Experimental and theoretical data can be drawn together by introducing a parameter of the interaction between the matrix material and filler, which is multiplied by the degree of filling, to the equation describing the E/E0 = f(φ) curve; in this case, however, two regions develop where these equations differ; this makes it possible to assume the presence of a percolation effect. 3. The dependence of composite strength on the logarithm of the characteristic dimension of the cell is described by two straight lines with different slopes; this also suggests the presence of a percolation effect. The value of the filler concentration for which these segments intersect is apparently close to the percolation concentration [11].

Two tensile-testing machines are described for physicomechanical tests of polymeric materials with deformation up to 100 and 1,000% in which the conditions of deformation are assigned directly to the measurement base of the specimen by using an automatically regulated electric drive, ensuring parity of the measured quantity (force, elongation, or stress) with the requisite preset functional controller.

A method of testing polyformaldehyde (acetyl resin) film has been developed. Comparative tests have been carried out on the homopolymer and trioxane-dioxolan copolymer. Certain physicomechanical characteristics of these polymers have been obtained.

A new opto-electronic strain meter is described. This instrument can be used to record tensile load-extension and elastic aftereffect diagrams for film microspecimens at a maximum elongation rate of 1 mm/sec and a resolution of 1.5µ.