Mechanical properties of a polyurethane-based composite modified with boron nitride

Polyurethane based composite formulation is developed, characterized by a significantly low amount of additives and their technological compatibility. It is shown that content of 0,05 mass% boron nitride in the polyurethane composition is optimal, as it leads to an increase in the mechanical strength of the film. This study presents temperature-time dependence of the mechanical strength of polyurethane films and the influence of BN additives on these characteristics. İt was defined that the observed increase in film strength at incorporating 0,05% by mass of BN to its content, associated with changes in the supramolecular structure, specifically the formation of spherulitic microstructure of supramolecular polyurethane. In the mechanical field, the bond rupture process is accelerated, thus the role of the load involves reducing bond energy, altering the distance between kinetic units, and fixing their movements, particularly difficulty of recombination of radicals. The structure of the formula in the durability equation suggests that the contribution of the load to bond rupture is represented by the term ασ mechanical field work. Throughout the entire range of applied loads, the product of ασ was significantly lower than activation energy. Therefore, the thermal fluctuations are the main factor causing breakdown, meaning the energy for body rupture is largely derived from thermal energy reserves rather than external work. Initial activation energy for mechanical failure of PU films and its optimally modified state remains unchanged. However, the additive influences to the magnitude of the structural sensitivity coefficient and the mechanical strength, so rupture occurs through chemical bonds.