The book presents in a relatively small volume modern ideas about the structure and mechanical properties of polymers. For the first time, attention is paid to modern ideas about the impact on the strength of those changes in structure and relaxation properties that occur from the beginning of deformation to the separation of the polymer body into parts. The increasing role of mixtures of polymers . is taken into account Modern ideas about aggregate, physical and phase states are presented, thermodynamics and kinetics of high-elastic deformation. are considered. To encourage students to work independently, each chapter contains questions, some of which may be a topic for writing an essay or a small business game. 4th edition (3rd released in 1979. ) significantly supplemented and revised by the authors.