The subject of this paper is to study the properties of compositions based on a modified polyethylene and a thermoplastic polyolefin structural features. As a result of the modification of polyethylene, the high elasticity of the material grows, which outwardly makes this polymer similar in complex to the physico-mechanical properties of rubber. The calculations made allowed us to estimate the parameters of the observed thermal transitions and to assign them to the mobility of specific elem ents of the structure