PREDICTION OF MECHANICAL PROPERTIES FOR ONE-DIMENSIONAL POLYMER STRUCTURES

Subject of Research. The paper presents a technique for prediction of the mechanical properties of polymer materials. An equation is proposed for the highly elastic part of deformation in a differential-mode for one-dimensional polymer structures. The equation establishes that the preceding mechanical impact on deformation material properties is irrelevant. Method. A recursive method for solution of the proposed differential equation not integrable in quadratures was proposed. Tensile diagrams were experimentally obtained for fibers made of highly oriented polymers such as polyamide and polyethylene terephthalate in five loading conditions. The first load consisted in uniform loading of the fiber to rupture. In the other cases, the loading was carried out in three stages: with holding at control points, complete unloading and subsequent loading to rupture. Main Results. An equation for the highly elastic part of the deformation in a differential form is proposed and solved. Tensile diagrams are presented for one-dimensional polymer samples made of polyamide and polyethylene terephthalate up to the rupture values under various loading conditions. It is found that the preceding mechanical impacts do not affect significantly on the sample deformation properties. Samples made of polyamide and polyethylene terephthalate have practically no memory. Thus, the highly elastic part of the deformation relaxes into a stable state. Practical Relevance. The research shows that in an equilibrium state (regardless of the deformation method) each level of mechanical stress corresponds to a certain value of the equilibrium deformation; for a fixed deformation there is a fixed value of stress. The modeling results make it possible to predict the behavior of polymer materials under various operating conditions