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nd. There are various mechanical models for the description of behavior of polymers and polymeric films under the influence of stretching forces. These models consider monoaxial stretching and therefore the corresponding parameters of process also concern only one direction. However, on condition of a solid body stretching there isn’t only a longitudinal, and cross deformation which significantly complicates the analysis of behavior of polymeric films in one – or two-axis stretching (orientation) process. Objective. The aim of the paper is to refine the deformation mechanism physical model of a tubular polymer film during its fabrication, creation of a mathematical model of the tube biaxial orientation process. Methods. The goal is achieved by considering the mechanical model of a polymer film as a square, the sides of which are successively connected with each other by Hooke and Newton elements, and the diagonals by Hooke elements. In this case, the joining points of the sides and diagonals of the square are hinged, and the Hooke elements can have various elasticity coefficients. Results. The dependence of the relative transverse deformation of the polymer film on the relative longitudinal deformation is obtained for both single- and biaxial stretching. The correctness of the deformation of the developed model at uniaxial stretching for the polymer melt was experimentally confirmed. It is shown that the maximum relative transverse strain at uniaxial stretching of the polymer melt doesn’t exceed 2/3 of its relative longitudinal deformation.Conclusions. The physical model of a tubular polymeric film deformation mechanism during its manufacture, based on a combination of Hooke and Newton elements, has been clarified. The model is valid for any moment of relaxation processes in a polymer film. The correctness of the model for real objects is experimentally proved. The effect of temperature on the ratio of longitudinal and transverse strains wasn’t experimentally detected.

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