A method is developed to determine approximate dynamic kinetic invariants (quasi-invariants) of complex chemical reactions with nonideal general-form kinetic laws. The quasi-invariants are...

A method has been developed for calculating the exact autonomous kinetic invariants of multistage linear chemical reactions occurring in a gradientless isothermal reactor via any number of elementary stages and involving an arbitrary number of reagents within the framework of mass-action law. These invariants are functions that remain strictly constant throughout the reaction (i.e., are time-independent), although they depend on the nonequilibrium reagent concentrations measured in two experiments with different initial conditions (dual experiments). For the dynamic models of linear reactions, one can always find general and particular analytical solutions expressed explicitly in terms of the initial conditions. The idea of the method is based on choosing the initial conditions that allow the nonequilibrium reagent concentrations to be expressed in terms of constant kinetic parameters (stage rate and flow rate constants). An applicability criterion of the method was formulated. The number of different invariants was shown to be equal to the number of reagents. The relations obtained in this study were used to investigate the relaxation properties of multistage linear reactions occurring in closed and open isothermal systems. The invariant curves found for these reactions were compared with the concentration curves measured in two nonequilibrium experiments throughout the transition process. For these reactions, the time dependences of the invariants remained strictly constant, while the reagent concentrations continuously changed (including nonmonotonously) during the reaction. The results give new insight into the relaxation of linear chemical reactions and can be used to solve the inverse problems of chemical kinetics under the conditions of an isothermal perfect-mixing reactor.

The mechanism of a chemical reaction in an ideal mixing reactor has been found. It was described by two ordinary differential equations within the framework of the law of mass action and reproduces...

The article studies the effect of trans-polynorbornene, general and special-purpose rubbers and fillers on the vulcanization characteristics of a rubber mixture, physical, mechanical, operational and dynamic properties of vulcanizates based on butadiene methylstyrene caoutchouc. The investigated model rubber mixture included SKMS-30ARK rubber, sulfur, 2,2'-dibenzthiazole disulfide, guanide F, zinc white, stearic acid, phenyl-2-naphthalamine, N-isopropyl-N'-phenyl-paraphenylenediamine, carbon blacks of grades P 514 and N 220, shungite powder and other ingredients. The rubber mixture was produced on laboratory rolls LB 320 160/160. The first (basic) version of the rubber mixture contained industrial oil I-12A as a softener. The second version of the mixture contained a modifying additive based on trans-polynorbornene and industrial oil I-12A. The third, fourth and fifth versions were prepared on the basis of a combination of rubbers SKM-S30ARK, SKN-4065 and BK-1675, including a modifying additive, as well as polyisobutylene P-118 and sevilen 11808-340. The vulcanization characteristics of the rubber mixture were studied on an MDR 3000 Basic rheometer at 150 degrees C for 30 min. To determine the physical and mechanical properties of rubber, standard samples of all variants of the rubber mixture were vulcanized at a temperature of 143 degrees C for 30 min in a vulcanization press of the P-V-100-3RT-2-PCD type. Studies of the physical, mechanical, operational and dynamic properties of rubber were carried out in accordance with the existing standards for the rubber industry. It is shown that vulcanizates containing a modifying additive have lower values of conventional tensile strength, hardness and tear resistance compared to vulcanizate of the base version of the rubber mixture and are characterized by increased dynamic and performance properties. Rubber containing a combination of butadiene-nitrile, butadiene-methylstyrene caoutchoucs and butyl caoutchouc, 10.0 mass parts sevilen 11808-340, 20.0 mass parts of trans-polynorbornene composed of in the modifying additive and 55.0 mass parts of carbon black P 324, possesses improved physical, mechanical and dynamic properties, as well as high resistance in sea water.