Due to the active development of the Northern and Arctic regions, modern damping materials for transport and construction infrastructure are subject to increased demands in terms of performance at low ambient temperatures. Theoretically, it has been shown that the restriction of segmental mobility and cold crystallization of polymers lead to an increase in stiffness and a decrease in damping and sealing functions. Formulations evolve through a controlled combination of base polymers, the introduction of "smart" fillers, technologically active additives, and the hybridization of elastomeric matrices. The evaluation of the low-temperature performance of elastomers is carried out based on the results of regulatory operational tests that simulate the maximum operating conditions of the product, and thermoanalytical / viscoelastic methods that reveal the physical nature of the transition to vitrification. However, these methods often lead to disparate results, are quite complex and require special high-precision equipment. In this regard, a method is proposed for rapid assessment of the low-temperature performance of elastomers based on the temperature dependence of Shore A hardness with the allocation of the T*hard criterion (fracture HRA(T)), which correlates with the glass transition temperature Tg, the brittleness temperature and the coefficient of frost resistance. The approbation was carried out on six polymer compositions of different nature, which showed that rubber elastomers (TPRK/TPRK-D) retain a highly elastic state up to minus 60 ° C (without the HRA(T) plateau), while thermoplastics demonstrate a sharp increase in hardness with saturation from minus 20 ° C, which indicates glass transition and limitation of use at lower temperatures. Statistical consistency (σ ≤ 3.6 units Shore A) confirms the reliability of the method. The proposed method is technologically advanced, recipe-sensitive, and suitable for primary ranking of frost resistance of seal and damper materials.

Keywords: elastomers, low-temperature performance, glass transition temperature, temperature limit of brittleness, coefficient of frost resistance, express assessment of low-temperature performance of elastomers based on the temperature dependence of Shore A

To implement effective adhesion of reinforcement to concrete, a large number of different types of periodic reinforcement profiles have recently been developed, the control of geometric parameters of which presents serious difficulties and allows for a high probability of measurement error. The urgency of the problem is due to the need to improve methods for measuring the geometric dimensions of reinforcement with a complex periodic profile in order to increase the accuracy of results along the entire length of the rod, the ability to measure the angles of inclination of axes, protrusions and dents, identify places of geometric stress concentrators to ensure the necessary quality of the finished product, reliable adhesion of reinforcement to concrete, increase the durability of reinforced concrete structures and products. The paper proposes a new method for measuring geometric parameters based on removing replicas from the surface of the reinforcement in different sections along the length of the rod. The analysis of prints presented in an expanded, flat form is carried out using counting and measuring devices, which significantly improves the accuracy and comparability of measurements, including angular dimensions. The use of modern optical devices and software for them helps to reduce the time for determining and visualizing geometric parameters, and improve measurement accuracy, which is measured in microns. The analysis of the obtained results showed an increase in the accuracy of measurements by removing replicas of geometric parameters of samples by 10-16.5% compared with traditional control methods. The developed method simplifies the measurement process, allows the use of alternative measuring instruments, a combination of calculation and instrument measurement methods.

Keywords: reinforced concrete products, profiles of reinforcing bars, methods of controlling geometric parameters, method of removing replicas, improving accuracy, reliability and comparability of measurements