Vulcanization and its features. Basic laws of the vulcanization process of rubbers of various nature System analysis of vulcanization kinetics

conclusions

Based on a system analysis of the galvanized strip gumming process, models and methods are identified, the use of which is necessary to implement the control method: a simulation model of the polymer coating drying process, a method for optimizing the technological parameters of the polymerization process based on a genetic algorithm, and a neuro-fuzzy process control model.

It has been determined that the development and implementation of a method for controlling the process of vulcanization of galvanized strip on a polymer coating unit based on neuro-fuzzy networks is a relevant and promising scientific and technical problem from the point of view of economic benefits, cost reduction and production optimization.

It has been established that the process of vulcanization of galvanized strip in the furnaces of a metal coating unit is a multi-connected object with parameters distributed along the coordinate, operating under non-stationary conditions and requiring a systematic approach to study.

The requirements for the mathematical support of the control system for multi-connected thermal objects of a metal coating unit have been determined: ensuring operation in direct communication with the object and in real time, a variety of functions performed while being relatively unchanged during operation, exchange of information with a large number of its sources and consumers in the process of solving basic problems, performance under conditions that limit the time for calculating control actions.

MATHEMATICAL SUPPORT FOR THE SYSTEM OF NEURAL-FUZZY CONTROL OF MULTI-CONNECTED THERMAL OBJECTS OF GUMMED METAL COATINGS UNIT

System analysis of control of multi-connected thermal objects of a rubberized coating unit

Conceptual design - initial stage design, at which decisions are made that determine the subsequent appearance of the system, and research and coordination of the parameters of the created solutions with their possible organization are carried out. Currently, it is gradually becoming realized that in order to build systems at a qualitatively different level of novelty, and not just modernize them, it is necessary to be armed with theoretical ideas about the direction in which systems are developing. This is necessary to organize the management of this process, which will increase both the quality indicators of these systems and the efficiency of the processes of their design, operation and operation.

At this stage, it is necessary to formulate a control problem, from which we obtain the research objectives. After analyzing the polymerization process of galvanized strip as a control object, it is necessary to determine the boundaries of the subject area that are of interest when constructing a process control model, i.e. determine the required level of abstraction of the models to be built.

The most important technique of systems research is the representation of any complex systems in the form of models, i.e. application of a method of cognition in which the description and study of the characteristics and properties of the original is replaced by a description and study of the characteristics and properties of some other object, which in general case has a completely different material or ideal representation. It is important that the model does not display the object of study itself in the form closest to the original, but only those of its properties and structures that are to a greater extent interested in achieving the research goal.

The control task is to set such values of the parameters of the galvanized strip vulcanization process that will allow achieving the maximum adhesion coefficient with minimal energy consumption.

There are a number of requirements for the quality of pre-painted rolled products produced, which are described in GOST, listed in section 1.3. The drying process in the ovens of the rubberized coating unit only affects the quality of adhesion to the substrate. Therefore, such defects as coating unevenness, gloss deviation and potholes are not considered in this work.

To carry out the drying process of a polymer coating, it is necessary to know the following set of technological parameters: temperatures of 7 furnace zones (Tz1...Tz7), line speed (V), density and heat capacity of the metal substrate (, s), thickness and initial temperature of the strip (h, Tinit.) , temperature range of polymerization of applied paint ().

In production, these parameters are usually called a recipe.

Parameters such as the power of fans installed in the furnace zones, the volume of clean air supplied, the parameters of the explosion hazard of varnishes are excluded from consideration, since they affect the rate of heating of the zones before drying and the concentration of explosive gases, which are not disclosed in this work. Their regulation is carried out separately from the control of the vulcanization process itself.

Let us determine the research tasks that need to be completed to achieve the management goal. Note that the current state of system analysis places special demands on decisions made based on the study of the obtained models. It is not enough to simply obtain possible solutions (in this case, the temperature values of the furnace zones) - it is necessary that they be optimal. System analysis, in particular, allows us to propose decision-making techniques for a targeted search for acceptable solutions by discarding those that are obviously inferior to others according to a given quality criterion. The purpose of its application to the analysis of a specific problem is to apply systems approach and, if possible, rigorous mathematical methods, to increase the validity of the decision made in the context of analyzing a large amount of information about the system and many potential solutions.

Due to the fact that at this stage we only know the input and output parameters of the models, we will describe them using a “black box” approach.

The first task that needs to be solved is to build a simulation model of the coating drying process, i.e. obtain a mathematical description of an object, which is used to conduct experiments on a computer for the purpose of designing, analyzing and assessing the functioning of the object. This is necessary to determine to what value the metal surface temperature (Tsur.out) will increase when leaving the furnace at given values of strip speed, thickness, density, heat capacity and initial temperature of the metal, as well as the temperatures of the furnace zones. In the future, a comparison of the value obtained at the output of this model with the temperature of paint polymerization will allow us to draw a conclusion about the quality of adhesion of the coating (Figure 10).

Figure 10 - Conceptual simulation model of the coating drying process

The second task is to develop a method for optimizing the technological parameters of the galvanized strip vulcanization process. To solve it, it is necessary to formalize the management quality criterion and build a model for optimizing technological parameters. Due to the fact that regulation temperature regime is carried out due to changes in the temperatures of the furnace zones (Tz1...Tz7), this model should optimize their values (Tz1opt...Tz7opt) according to the control quality criterion (Figure 11). This model also receives vulcanization temperatures as input, since without them it is impossible to determine the quality of paint adhesion to the metal substrate.

Figure 11 - Conceptual model for optimization of process parameters

Sergei G. Tikhomirov, Olga V. Karmanova, Yuri V. Pyatakov, Alexander A. Maslov Enter the title of the article here Sergei G. Tikhomirov, Olga V. Karmanova, Yurii V. Pyatakov, Ale ksandr A. Maslov Enter the title of the article here on English language Bulletin of VGUIT/Proceedings of VSUET, 3, 06 Review article/eview article UDC 6.53 DOI: http://doi.org/0.094/30-0-06-3-93-99 Software package for solving problems of mathematical modeling of the isothermal vulcanization process Sergey G. Tikhomirov, Olga V. Karmanova, Yuri V. Pyatakov, Alexander A. Maslov [email protected] [email protected] [email protected] [email protected] Department of Information and Control Systems, Voronezh. state univ. Eng. Tekhn., Revolution Ave., 9, Voronezh, Russia Department of Chemistry and Chemical Technology of Organic Compounds and Polymer Processing, Voronezh. state univ. Eng. Tekhn., Leninsky Ave., 4, Voronezh, Russia Abstract. Based on the general principles of sulfur vulcanization of diene rubbers, the principles of effective process implementation using multicomponent structuring systems are considered. It is noted that the description of the mechanism of action of complex cross-linking systems is complicated by the variety of interactions of the components and the influence of each of them on the kinetics of vulcanization, which leads to various recipe and technological complications of the actual technology and affects the quality and technical and economic indicators of the production of rubber products. A system analysis of the isothermal vulcanization process was carried out on the basis of well-known theoretical approaches and included the integration of various research methods and techniques into a single interconnected set of methods. During the analysis of vulcanization kinetics, it was found that the parameters for the formation of a spatial network of vulcanizates depend on many factors, the assessment of which requires special mathematical and algorithmic software. As a result of the stratification of the studied object, the main subsystems were identified. A software package has been developed for solving direct and inverse kinetic problems of the isothermal vulcanization process. The information support “Isothermal vulcanization” is developed in the form of application programs for mathematical modeling of the isothermal vulcanization process and is aimed at solving direct and inverse kinetic problems. When solving the refinement problem general scheme chemical transformations, a universal mechanism was used, including side chemical reactions. The software product includes numerical algorithms solving a system of differential equations. To solve the inverse kinetic problem, functional minimization algorithms are used in the presence of restrictions on the required parameters. To describe how to work with this product, a logical block diagram of the program is provided. An example of solving an inverse kinetic problem using the program is given. The developed information support is implemented in the C++ programming language. To determine the initial concentration of the actual vulcanization agent, a universal dependence was used, which allows the use of a model with various properties of multicomponent structuring systems Key words: isothermal vulcanization, mathematical modeling, vulcanization kinetics diagram, information support The software package for solving problems of mathematical modeling of isothermal curing process Sergei G Tikhomirov, Olga V. Karmanova, Yurii V. Pyatakov, Aleksandr A. Maslov [email protected] [email protected] [email protected] [email protected] information and control systems department, Voronezh state university of engineering technologies, evolution Av., 9 Voronezh, ussia chemistry and chemical technology of organic compounds and polymers processing department, Voronezh state university of engineering technologies, Leninsky Av., 4 Voronezh, ussia Summary. On the basis of the general laws of sulfur vulcanization diene rubbers the principles of the effective cross-linking using a multi-component agents was discussed. It is noted that the description of the mechanism of action of the complex cross-linking systems are complicated by the diversity of interactions of components and the influence of each of them on the curing kinetics, leading to a variety of technological complications of real technology and affects on the quality and technical and economic indicators of the production of rubber goods. based on the known theoretical approaches the system analysis of isothermal curing process was performed. It included the integration of different techniques and methods into a single set of. During the analysis of the kinetics of vulcanization it was found that the formation of the spatial grid parameters vulcanizates depend on many factors, to assess which requires special mathematical and algorithmic support. As a result of the stratification of the object were identified the following major subsystems. A software package for solving direct and inverse kinetic problems isothermal curing process was developed. Information support Isothermal vulcanization is a set of applications of mathematical modeling of isothermal curing. It is intended for direct and inverse kinetic problems. When solving the problem of clarifying the general scheme of chemical transformations used universal mechanism including secondary chemical reactions. Functional minimization algorithm with constraints on the unknown parameters was used for solving the inverse kinetic problem. Shows a flowchart of the program. An example of solving the inverse kinetic problem with the program was introduced. Dataware was implemented in the programming language C++. Universal dependence to determine the initial concentration of the curing agent was applied. It allows the use of a model with different properties of multicomponent curing systems. informed decisions. Keywords: isothermal curing, mathematical modeling, the scheme of the curing kinetics, informational software For citation Tikhomirov S.G., Karmanova O. V., Pyatakov Yu.V., Maslov A.A. Software package for solving problems of mathematical modeling of the isothermal vulcanization process // Vestnik VGUIT. 06. 3. S 93 99. doi:0.094/30-0-06-3-93-99 For citation Tihomirov S.G., Karmanova O.V., Pyatakov Yu.V., Maslov A.A The software package for solving problems of mathematical modeling of isothermal curing process. Vestnik VSUET. 06. no 3 pp. 93 99 (in uss.). doi:0.094/30-0-06-3-93-99 93

Bulletin of VGUIT/Proceedings of VSUET, 3, 06 94 Introduction To date, general principles of sulfur vulcanization of diene rubbers have been established, based on the existence of real elastomer vulcanization agents (EAVs) in the compositions. However, the principles of effective implementation of the process using multicomponent structuring systems have not been sufficiently studied. The description of the mechanism of their action is complicated by the variety of interactions of the components and the influence of each of them on the kinetics of vulcanization. This leads to various recipe and technological complications of the actual technology and affects the quality and technical and economic indicators of the production of rubber products. Analysis of the kinetics of vulcanization has shown that existing approaches to its description are based on chemical reactions of macromolecules with vulcanizing agents, and the parameters for the formation of a spatial network of vulcanizers depend on many factors, the influence of which can only be assessed using special mathematical and algorithmic software. To increase the efficiency of research, identify the reasons leading to the production of products that do not meet regulatory requirements, and predict the course of the process, it is necessary to create a special software(BY). The purpose of this work is to develop a software package for solving direct and inverse kinetic problems of the isothermal vulcanization process. System analysis of the vulcanization process Analysis of known theoretical approaches to the description of vulcanization, as well as other processes in the chemical industry [4] and aspects of their practical implementation, taking into account the characteristics of individual stages, made it possible to identify general system properties and basic patterns of processes and determine the direction of research to obtain new information on optimization of vulcanization modes and properties of finished products. System analysis includes the integration of various research methods and techniques (mathematical, heuristic), developed within the framework of various scientific fields into a single interconnected set of methods. Multivariate analysis of the process allowed us to develop the general structure of the study (Figure). The object of study is weakly structured, since it contains both high-quality elements (elastomers, fillers, process conditions) and little-studied ones (multicomponent structuring systems, uncontrolled disturbances), which tend to dominate. The general structure includes elements that need to be theoretically justified (kinetic model, heat and mass transfer processes, mode optimization, processing processes). Thus, to evaluate solution methods, it is necessary to identify all existing relationships and establish their influence, taking into account interactions on the behavior of the entire system as a whole. Analysis of the general structure showed that the mechanical properties of vulcanizates are determined by the chemical reactions of macromolecules with vulcanizing agents, and to assess the parameters of the spatial network of vulcanizates it is necessary to develop special mathematical and algorithmic software. As a result of the stratification of the studied object, the following main subsystems were identified:) analysis and accounting of thermal fluctuation phenomena that ensure acceleration of the chemical reactions;) kinetic model of vulcanization; 3) optimization of vulcanization modes, ensuring the required mechanical properties. Mathematical modeling of the isothermal vulcanization process Obtaining reliable information about the processes of cross-linking elastomers with complex structuring systems is closely related to the problems of design, optimization and control of vulcanization modes in industry. It is known that one of the traditional ways of describing the formal kinetics of vulcanization is the use of piecewise defined functions for individual stages of the process: induction period, structuring and reversion. The description of the process as a whole and the calculation of kinetic constants have currently been carried out only for certain types of rubbers and vulcanizing systems. The main conclusions about the kinetics of the process are based on model systems with low molecular weight analogues of elastomers. At the same time, it is not always possible to extend the obtained quantitative data to production processes.

Bulletin of VSUIT/Proceedings of VSUET, 3, 06 Figure. Scheme of studying the process of vulcanization of elastomers Figure. Scheme of study process of vulcanization of elastomers Assessment of the physical and mechanical properties of industrial rubbers, according to data obtained at the enterprise, is, of course, a progressive method in solving the problem of modeling the vulcanization process, but requires strict internal unity of the physical and chemical approach at each stage of the study and development of computational algorithms and programs. This question can only be answered by carefully performing experiments according to a design consistent with the proposed kinetic model and calculating several alternative versions of the model. This requires an independent method to establish the number of formal reaction mechanisms responsible for the structuring of the elastomeric composition. Traditional methods Analysis of processes in the time domain does not make it possible to clearly separate processes with synergistic interactions, which, in turn, does not allow their use for the analysis of industrial rubbers. When solving the problem of clarifying the general scheme of chemical transformations, it is advisable to proceed from a mechanism that is maximal in a certain sense. Therefore, the kinetic scheme includes additional reactions describing the formation and destruction of labile polysulfide bonds (Vu lab), intramolecular cyclization and other reactions leading to the modification of macromolecules, the formation of a macroradical and its reaction with DAV pendants. The system of differential equations (DE) for the stages of the process will have next view: dca / dt k CA k4ca C *, dc / dt k CA kc k4ca C * k 8C *, dc * / dt k C k3 k5 k7 C * k C k C C, 6 VuLab 4 A * dcvust / dt k3 C * , dcvulab / dt k5c k6cvulab, dcc / dt k7 C *, dc * / dt k8c k 8C *, dc / dt k8 C. () 95

Bulletin of VGUIT/Proceedings of VSUET, 3, 06 96 Initial conditions: 0 0 CA S8 AC Akt C ; C 0 0; C 0 0; * VuSt C 0 0; C 0 0; VuLab C C 0 C 0, * C 0 0; C0 4.95; where ς, θ, η, coefficients, initial concentration of sulfur, initial concentration of accelerator, θ initial concentration of activator (zinc oxide), [C (0)] η initial concentration of macroradicals. Here A is the actual vulcanizing agent; The precursor to stitching; B* its active form; C intramolecular bound sulfur; VuSt, VuLab stable and labile vulcanization mesh units; rubber; * rubber macroradical as a result of thermal fluctuation decomposition; α, β, γ and δ stoichiometric coefficients, k, k, k 8, k 9 (k 8) reaction rate constants related to the corresponding stages of the process. The direct kinetics problem (DKP) is the task of finding the concentration of vulcanization units as a function of time. The solution of the PZK is reduced to the solution of the DE system () under given initial conditions. The kinetic curve of the vulcanization process is determined by the magnitude of the torque Mt. Inverse kinetics problem (IKP) is the problem of identifying reaction rate constants, stoichiometric coefficients and variables in the system (). The OZK solution is carried out by minimizing the functional: where Ф k, k,..., k, k, 8 8 t к q k, k,..., k8, k 8, tdt 0 q k, k,..., k, k, t 8 8 M t M M M С min / max min Vu (), (3) M max, M min respectively the maximum and minimum values of the coefficient. Mt, large-scale Description of the software The “Isothermal vulcanization” software is developed as a set of application programs (APP) for solving problems associated with mathematical modeling of the isothermal vulcanization process. To solve the DE system, the package provides numerical methods, including: the fourth-order Runge-Kutta method; Adams method. The solution of the inverse kinetic problem comes down to estimating reaction rate constants, stoichiometric coefficients and variables in the DE system (). To minimize the functionality () in the software package, the following methods can be used at the user's discretion: coordinate descent, Hook-Jeeves, Rosenbrock, Powell, Nelder-Mead, coordinate averaging (using random search elements). Gradient methods (first order): steepest descent, conjugate directions (Fletcher-Reeves), variable metric (Davidon-Fletcher-Powell), parallel gradients (Zangwill). The figure shows a block diagram of the developed software. The process of identifying reaction rate constants, equation coefficients and stoichiometric coefficients is carried out in several stages: digitization of rheograms; translation of torques into concentrations; determination of initial concentrations; determination of the values of the required parameters of constants that provide a minimum of functionality (). Digitization of rheograms can be done manually or automatically using the GrDigit program integrated into the package. Processing of experimental data can be carried out both for one measurement and for a set (up to 6 rheograms). The conversion of torques into the concentration of vulcanization mesh nodes is carried out as follows: the values of torques are converted into conventional units: conventional / M M M M M (4) tech min max min then conventional units are converted to (mol/kg) by multiplying M conventional by a scale factor. Determination of the initial concentrations of C 0 DAV is carried out according to the formula: A 0 0 CA S8 AC Akt C (5)

Bulletin of VSUIT/Proceedings of VSUET, 3, 06 Figure. Software block diagram Figure. Structural software scheme Approbation of the developed software. Rheometric curves obtained under the following initial conditions were used as initial data:. The value of sulfur concentration in the mixture: = 0.0078 mol/kg. Accelerator concentration: = 0.009 mol/kg. 3. Activator concentration: θ = 0.00 mol/kg. Figure 3 shows the experimental and calculated values of the concentration of vulcanization units obtained as a result of solving the OKZ. The table shows the calculated values of the reaction rate constants, the table shows the estimated values of the stoichiometric coefficients and model parameters. Table The value of the reaction rate constants Table The value of the reaction rate constants Constant Constant Values Constant Constant Values Values k 0, k6 0.553 k 0, k7 0.96 k3 4.8 0-0 k8.3 k4.3 k8" 0, k5.89 0-0 Figure 3. Changes in the concentrations of the vulcanization grid points in time. the calculated values; experimental values. Digitized and processed experimental data are entered into the program, the initial ones are determined approximations and the range of searching for constants, after which the optimization method is selected. Table The values of stoichiometric coefficients and parameters of the model pas α β γ δ ξ θ η,4,0,9,65 0 8 0, 97-4, 97

Bulletin of VGUIT/Proceedings of VSUET, 3, 06 Conclusion Based on a systematic analysis of theoretical approaches to the description of vulcanization, the general structural diagram of the study of this process has been improved. The mathematical model of the vulcanization process is supplemented with initial conditions, which are defined as functions of the initial concentrations of the components of the vulcanizing group. To solve the inverse kinetic problem, additional criteria for the quality of the model are proposed. A software product has been developed designed for carrying out research work in the study of vulcanization processes of rubber compounds using multicomponent structuring systems. The gearbox has a block-modular structure, which allows its expansion without loss of functionality. The directions for its modernization are the inclusion in the mathematical description of the non-isothermal vulcanization mode with further integration into the automated process control system circuit as an expert information and management system for issuing recommendations for managing the vulcanization process and making decisions. The work was carried out with the financial support of state assignment 04/ (research number 304) on the topic “Synthesis of multifunctional quality control systems for the food and chemical industry” REFERENCES Tikhomirov S.G., Bityukov V.K., Podkopaeva S.V., Khromykh E. A. and others. Mathematical modeling of control objects in the chemical industry. Voronezh: VGUIT, 0. 96 p. Khaustov I.A. Control of polymer synthesis by batch method based on fractional supply of reaction components // Vestnik TSTU. 04. 4 (0) P. 787 79. 3 Khaustov I.A. Control of the process of destruction of polymers in solution based on fractional loading of the initiator // Vestnik VGUIT. 04. 4. P. 86 9. 4 Bityukov V.K., Khaustov I.A., Khvostov A.A. and others. System analysis of the process of thermal-oxidative destruction of polymers in solution as a control object // Vestnik VGUIT. 04.3 (6). P. 6 66. 5 Karmanova O.V. Physico-chemical foundations and activating components of polydiene vulcanization: dissertation. Dr. Tech. Sci. Voronezh, 0. 6 Molchanov V.I., Karmanova O.V., Tikhomirov S.G. Modeling the kinetics of vulcanization of polydienes // Vestnik VGUIT. 03.. P. 4 45. 7 Hardis., Jessop J.L.P., Peters F.E., Kessler M.. Cure kinetics characterization and monitoring of an epoxy resin using DSC, aman spectroscopy, and DEA // Composite. 03. Part A. V. 49. P. 00 08. 8 Javadi M., Moghiman M., eza Erfanian M., Hosseini N. Numerical Investigation of Curing Process in reaction Injection Molding of rubber for Quality Improvements // Key Engineering Materials. 0. V. 46 463. P. 06. EFEENCES Tikhomirov S.G., ityukov V.K. Podkopaeva S.V., Khromykh E.A. et al. Matematicheskoe modeling ob ektov upravleniya v khimicheskoi promyshlennosti Voronezh, VSUET, 0. 96 p. (in ussian). Khaustov I.A. Management polymer synthesis batch process based on the fractional flow of the reaction components. Vestnik TGTU 04, no. 4 (0), pp. 787 79. (in ussian). 3 Khaustov I.A. Process control degradation of polymers in the solution based on the fractional loading of the initiator. Vestnik VGUIT 04, no. 4, pp. 86 9 (in ussian). 4 ityukov V.K., Khaustov I.A., Khvostov A.A. System analysis of the thermooxidative degradation of polymers in solution as a control object. Vestnik VGUIT 04, no. 3 (6), pp. 6 66. (in ussian). 5 Karmanova O.V. Fiziko-khimicheskie osnovy i aktiviruyushchie komponenty vulknizatsii polidienov Voronezh, 0. (in ussian). 6 Molchanov V.I., Karmanova O.V., Tikhomirov S.G. Modeling the kinetics of vulcanization polydienes. Vestnik VGUIT 03, no., pp. 4 45. (in ussian). 7 Hardis., Jessop J.L.P., Peters F.E., Kessler M.. Cure kinetics characterization and monitoring of an epoxy resin using DSC, aman spectroscopy, and DEA. Composite, 03, part A, vol. 49, pp. 00 08. 8 Javadi M., Moghiman M., eza Erfanian M., Hosseini N. Numerical Investigation of Curing Process in reaction Injection Molding of rubber for Quality Improvements. Key Engineering Materials. 0, vol. 46 463, pp. 06.98

Bulletin of VSUIT/Proceedings of VSUET, 3, 06 INFORMATION ABOUT THE AUTHORS Sergey T. Tikhomirov Professor, Department of Information and Control Systems, Voronezh State University Engineering Technologies, Revolution Ave., 9, Voronezh, 394036, Russia, [email protected] Olga V. Karmanova Head Department, Professor, Department of Chemistry and Chemical Technology of Organic Compounds and Polymer Processing, Voronezh State University of Engineering Technologies, Leninsky Prospekt, 4, Voronezh, 394000, Russia, [email protected] Yuri V. Pyatakov Associate Professor, Department of Information and Control Systems, Voronezh State University of Engineering Technologies, Revolution Ave., 9, Voronezh, 394036, Russia, [email protected] Alexander A. Maslov postgraduate student, Department of Information and Control Systems, Voronezh State University of Engineering Technologies, Revolution Ave., 9, Voronezh, 394036, Russia, [email protected] INFOMATION AOUT AUTHOS Sergei G. Tikhomirov professor, department of information and control systems, Voronezh state university of engineering technologies, evolution Av., 9 Voronezh, ussia, [email protected] Olga V. Karmanova professor, head of department, department of chemistry and chemical technology of organic compounds and polymers processing, Voronezh state university of engineering technologies, Leninsky Av., 4 Voronezh, ussia, [email protected] Yurii V. Pyatakov associate professor, department of information and control systems, Voronezh state university of engineering technologies, evolution Av., 9 Voronezh, ussia, [email protected] Aleksandr A. Maslov graduate student, department of information and control systems, Voronezh state university of engineering technologies, evolution Av., 9 Voronezh, ussia, [email protected] AUTHORITY CRITERION Sergei T. Tikhomirov proposed a methodology for conducting an experiment and organized production tests Alexander A. Maslov reviewed literature sources on the problem under study, conducted an experiment, performed calculations Olga V. Karmanova consultation during the study Yuri V. Pyatakov wrote the manuscript, corrected it before submission to editor and is responsible for plagiarism CONFLICT OF INTEREST The authors declare that there is no conflict of interest. CONTIUTION Sergei G. Tikhomirov proposed a scheme of the experiment and organized production trials Aleksandr A. Maslov review of the literature on an investigated problem, conducted an experiment, performed computations Olga V. Karmanova consultation during the study Yurii V. Pyatakov wrote the manuscript, correct it before filing in editing and is responsible for plagiarism CONFLICT OF INTEEST The authors declare no conflict of interest. RECEIVED 7.07.06 ECEIVED 7.7.06 ACCEPTED FOR PRINT.08.06 ACCEPTED 8..06 99

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VulcanizAtion-- a technological process of interaction of rubbers with a vulcanizing agent, during which rubber molecules are cross-linked into a single spatial network. Vulcanizing agents can be: sulfur, peroxides, metal oxides, amine-type compounds, etc. To increase the rate of vulcanization, various accelerator catalysts are used.

Vulcanization increases the strength characteristics of rubber, its hardness, elasticity, heat and frost resistance, and reduces the degree of swelling and solubility in organic solvents. The essence of vulcanization is the connection of linear macromolecules of rubber into a single “cross-linked” system, the so-called vulcanization network. As a result of vulcanization, cross-links are formed between macromolecules, the number and structure of which depend on method B. During vulcanization, some properties of the vulcanized mixture do not change monotonically over time, but pass through a maximum or minimum. The degree of vulcanization at which the best combination of various physical and mechanical properties of rubber is achieved is called the vulcanization optimum.

Vulcanization is usually carried out on a mixture of rubber with various substances that provide the necessary performance properties of rubber (fillers, for example, soot, chalk, kaolin, as well as softeners, antioxidants, etc.).

In most cases, general purpose rubbers (natural, butadiene, styrene butadiene) are vulcanized by heating them with elemental sulfur at 140-160°C (sulfuric acid). The resulting intermolecular cross-links occur through one or more sulfur atoms. If 0.5-5% sulfur is added to rubber, a soft vulcanizate is obtained (car tubes and tires, balls, tubes, etc.); the addition of 30-50% sulfur leads to the formation of a hard, inelastic material - ebonite. Sulfur vulcanization can be accelerated by adding small amounts of organic compounds, so-called vulcanization accelerators - captax, thiuram, etc. The effect of these substances is fully manifested only in the presence of activators - metal oxides (most often zinc oxide).

In industry, sulfur vulcanization is carried out by heating the vulcanized product in molds under high blood pressure or in the form of non-molded products (in “free” form) in boilers, autoclaves, individual vulcanizers, and devices for continuous vulcanization. etc. In these devices, heating is carried out with steam, air, superheated water, electricity, and high-frequency currents. The molds are usually placed between heated platens of a hydraulic press. Vulcanization with sulfur was discovered by C. Goodyear (USA, 1839) and T. Hancock (Great Britain, 1843). For the vulcanization of special-purpose rubbers, organic peroxides (for example, benzoyl peroxide), synthetic resins (for example, phenol-formaldehyde), nitro- and diazo compounds and others are used; The process conditions are the same as for sulfur vulcanization.

Vulcanization is also possible under the influence of ionizing radiation - g-radiation from radioactive cobalt, a flow of fast electrons (radiation vulcanization). Sulfur-free and radiation rubber methods make it possible to obtain rubbers that have high thermal and chemical resistance.

In the polymer industry, vulcanization is used in the extrusion production of rubber.

Vulcanization at prepairetires

The technological process of tire repair consists of preparing damaged areas for applying repair materials, applying repair materials to damaged areas and vulcanizing the areas being repaired.

Vulcanization of the repaired areas is one of the most important operations when repairing tires.

The essence of vulcanization is that when heated to a certain temperature, a physicochemical process occurs in unvulcanized rubber, as a result of which the rubber acquires elasticity, strength, resilience and other necessary qualities.

When two pieces of rubber glued together with rubber glue are vulcanized, they turn into a monolithic structure and the strength of their connection does not differ from the adhesion strength of the base material inside each piece. At the same time, to ensure the necessary strength, the pieces of rubber must be pressed - pressed under a pressure of 5 kg/cm 2.

In order for the vulcanization process to take place, it is not enough to only heat it to the required temperature, i.e., to 143+2°; The vulcanization process does not occur instantly, so heated tires must be kept for a certain time at the vulcanization temperature.

Vulcanization can occur at lower temperatures than 143°, but it takes longer. So, for example, if the temperature decreases from the specified one by only 10°, the vulcanization time should be doubled. In order to reduce the time for preheating during vulcanization, electric cuffs are used, which allow heating simultaneously on both sides of the tire, thereby reducing the vulcanization time and improving the quality of repairs. When one-sided heating of tires of large thickness occurs, over-vulcanization of rubber sections in contact with vulcanization equipment occurs, and under-vulcanization of rubber with opposite side. Vulcanization time, depending on the type of damage and tire size, ranges from 30 to 180 minutes for tires and from 15 to 20 minutes for tubes

For vulcanization in motor vehicles, a stationary vulcanization apparatus model 601, produced by the GARO trust, is used.

The working set of the vulcanization apparatus includes corsets for sectors, corset tightening, tread and side profile linings, clamps, pressure pads, sand bags, mattresses.

With a steam pressure in the boiler of 4 kg/cm2, the required surface temperature of the vulcanization equipment is 143"+2°. At a pressure of 4.0--4.1 kg/cm2, the safety valve must open.

Vulcanizing devices must be inspected by a boiler inspector before being put into operation.

Internal damage to tires is vulcanized on sectors, external damage is cured on slabs using profile linings. Through damage (in the presence of electric cuffs, they are vulcanized on a plate with a profile lining, in the absence of electric cuffs, separately: first from the inside on the sector, then from the outside on a plate with a profile lining.

The electric cuff consists of several layers of rubber and an outer layer of rubberized chafer, in the middle of which there is a spiral of nichrome wire for heating and a thermostat to maintain a constant temperature (150°).

vulcanization industry tire repair

Rice. 4. Stationary vulcanizing apparatus GARO model 601: 1 - sector; 2 -- side plate; 3 -- boiler-steam generator; 4 -- small clamps for cameras; 5 -- bracket for cameras; 6 -- pressure gauge; 7-clamp for tires; 8 - firebox; 9 -- water meter glass; 10 -- manual plunger pump; 11 -- suction tube

Before vulcanization, the boundaries of the tire area to be repaired are marked. To eliminate sticking, powder it with talcum powder, as well as a sand bag, an electric cuff and vulcanization equipment (sectors, profile linings, etc.) in contact with the tire.

When vulcanizing on a sector, crimping is achieved by tightening a corset, and when vulcanizing on a slab, using a bag of sand and a clamp.

Profile linings (tread and bead) are selected in accordance with the location of the tire being repaired and its size.

During vulcanization, the electric cuff is located between the tire and the sand bag.

The start and end times of vulcanization are marked with chalk on a special board installed near the vulcanization equipment.

Repaired tires must meet the following requirements:

1) tires should not have unrepaired areas;

2) on the inside of the tire there should be no swelling or traces of patch delamination, under-vulcanization, folds or thickenings that impair the performance of the tube;

3) the rubber sections applied along the tread or sidewall must be completely vulcanized to a Shore hardness of 55-65;

4) tread areas larger than 200 mm restored during the repair process must have a pattern identical to the entire tread of the tire; an “All-terrain vehicle” pattern must be applied regardless of the size of the restored tread area;

5) the shape of the tire beads should not be distorted;

6) thickenings and depressions that distort the external dimensions and surface of the tire are not allowed;

7) repaired areas should not have any backlogs; the presence of shells or pores up to 20 mm 2 in area and up to 2 mm in depth is allowed in an amount of no more than two per square decimeter;

8) the quality of tire repair must ensure their guaranteed mileage after repair.

Vulcanization at prepairecameras

Similar to the tire repair process, the tube repair process consists of preparing damaged areas for patching, patching, and curing.

The scope of work to prepare damaged areas for patching includes: identifying hidden and visible damage, removing old unvulcanized patches, rounding edges with sharp corners, roughening rubber around the damage, cleaning chambers from roughening dust.

Rice. 5. Sector for vulcanization of tires: 1 -- sector; 2 -- tire; 2 -- corset; 4 -- tighten

Rice. 6. Vulcanization of bead damage to the tire on the bead plate: 1 - tire; 2 -- side plate: 3 -- side lining; 4 -- sandbag; 5 -- metal plate; 6 -- clamp

Visible damage is revealed by external inspection in good lighting and outlined with a chemical pencil.

To identify hidden damage, i.e. small punctures that are invisible to the eye, the camera, in an inflated state, is immersed in a bath of water, and the puncture site is determined by the escaping air bubbles, which is also outlined with a chemical pencil. The damaged surface of the chamber is roughened with a carborundum stone or a wire brush at a width of 25-35 mm from the boundaries of the damage, preventing roughening dust from getting inside the chamber. Rough areas are cleaned with a brush.

Repair materials for repairing inner tubes are: unvulcanized inner tube rubber 2 mm thick, rubber for inner tubes unsuitable for repair, and rubberized chafer. All punctures and tears up to 30 mm in size are sealed with raw, unvulcanized rubber. Damage greater than 30 mm is repaired using rubber for cameras. This rubber must be elastic, without cracks or mechanical damage. Raw rubber is refreshed with gasoline, coated with glue with a concentration of 1:8 and dried for 40-45 minutes. The chambers are roughened with a wire brush or carborundum stone on a roughening machine, after which they are cleaned of dust, refreshed with gasoline and dried for 25 minutes, then coated twice with glue with a concentration of 1: 8 and dried after each application for 30-40 minutes at a temperature 20--30°. The chafer is coated once with glue with a concentration of 1:8, then dried.

The patch is cut out in such a way that it covers the hole on all sides by 20-30 mm and is 2-3 mm smaller than the boundaries of the rough surface. It is applied to the repaired area of the chamber with one side and gradually rolled with a roller over the entire surface, so that there are no air bubbles left between it and the chamber. When gluing patches, you must ensure that the surfaces to be glued are completely clean, free from moisture, dust and greasy stains.

In cases where the chamber has a tear of more than 500 mm, it can be repaired by cutting out the damaged piece and inserting in its place the same piece from another chamber of the same size. This repair method is called chamber joining. The width of the joint must be at least 50 mm.

Damaged external threads of valve bodies are restored using dies, and internal threads are restored using taps.

If it is necessary to replace the valve, it is cut out together with the flange and another valve is vulcanized in the new location. The location of the old valve is repaired as normal damage.

Vulcanization of damaged areas is carried out using a model 601 vulcanization apparatus or a GARO vulcanization apparatus for vulcanizing chambers. Vulcanization time for patches is 15 minutes and flanges are 20 minutes at a temperature of 143+2°.

During vulcanization, the chamber is pressed with a clamp through a wooden plate to the surface of the plate. The overlay should be 10-15 mm larger than the patch.

If the area to be repaired does not fit on the slab, then it is vulcanized in two or three successive installations (rates).

After vulcanization, the beads on the unroughened surface are cut off with scissors, and the edges of the patches and burrs are removed on the stone of a roughening machine.

Repaired cameras must meet the following requirements:

1) the chamber filled with air must be sealed both along the body of the chamber and at the place where the valve is attached;

2) the patches must be tightly vulcanized, free from bubbles and porosity, their hardness must be the same as the rubber of the camera;

3) the edges of patches and flanges should not have thickenings or peeling;

4) the valve thread must be in good condition.

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Vulcanization process

The rubber vulcanization process can be divided into cold and hot. The first one can be divided into two types. The first involves the use of sulfur semichloride. The mechanism of vulcanization using this substance looks like this. A workpiece made of natural rubber is placed in the vapor of this substance (S2Cl2) or in its solution, made on the basis of some solvent. The solvent must meet two requirements:

It should not react with sulfur semichloride.
It should dissolve the rubber.

As a rule, carbon disulfide, gasoline and a number of others can be used as a solvent. The presence of sulfur semichloride in the liquid prevents the rubber from dissolving. The essence of this process is to saturate the rubber with this chemical.

The duration of the vulcanization process with the participation of S2Cl2 ultimately determines specifications finished product, including elasticity and strength.

The vulcanization time in a 2% solution can be several seconds or minutes. If the process takes too long, so-called over-vulcanization may occur, that is, the workpieces lose their plasticity and become very brittle. Experience suggests that with a product thickness of about one millimeter, the vulcanization operation can be carried out in a few seconds.

This vulcanization technology is the optimal solution for processing parts with a thin wall - tubes, gloves, etc. But, in this case, it is necessary to strictly observe the processing modes; otherwise, the top layer of parts can be vulcanized more than the inner layers.

At the end of the vulcanization operation, the resulting parts must be washed with either water or an alkaline solution.

There is a second method of cold vulcanization. Rubber blanks with a thin wall are placed in an atmosphere saturated with SO2. After a certain time, the workpieces are moved into a chamber where H2S (hydrogen sulfide) is pumped. The holding time of workpieces in such chambers is 15 – 25 minutes. This time is sufficient to complete vulcanization. This technology is successfully used for processing glued seams, which gives them high strength.

Special rubbers are processed using synthetic resins; vulcanization using them is no different from that described above.

Hot vulcanization

The technology for such vulcanization is as follows. A certain amount of sulfur and special additives are added to the molded raw rubber. As a rule, the volume of sulfur should be in the range of 5 – 10%; the final figure is determined based on the purpose and hardness of the future part. In addition to sulfur, so-called horn rubber (hard rubber) containing 20–50% sulfur is added. At the next stage, blanks are formed from the resulting material and heated, i.e. curing.

Heating is carried out using various methods. The blanks are placed in metal molds or rolled into fabric. The resulting structures are placed in an oven heated to 130 - 140 degrees Celsius. In order to increase the efficiency of vulcanization, excess pressure can be created in the oven.

The formed blanks can be placed in an autoclave containing superheated water vapor. Or they are placed in a heated press. In fact, this method is the most common in practice.

The properties of vulcanized rubber depend on many conditions. That is why vulcanization is considered one of the most complex operations used in rubber production. In addition, the quality of the raw material and the method of its pre-processing play an important role. We must not forget about the volume of added sulfur, temperature, duration and method of vulcanization. In the end, the properties of the finished product are also affected by the presence of impurities. of different origins. Indeed, the presence of many impurities allows for proper vulcanization.

IN last years accelerators began to be used in the rubber industry. These substances added to the rubber mixture speed up the processes, reduce energy costs, in other words, these additives optimize the processing of the workpiece.

When implementing hot vulcanization in air, the presence of lead oxide is necessary; in addition, the presence of lead salts may be required in combination with organic acids or with compounds that contain acid hydroxides.

The following substances are used as accelerators:

thiuramid sulfide;
xanthates;
Mercaptobenzothiazole.

Vulcanization carried out under the influence of water vapor can be significantly reduced if such chemical substances, as alkalis: Ca(OH)2, MgO, NaOH, KOH, or salts Na2CO3, Na2CS3. In addition, potassium salts will help speed up the processes.

There are also organic accelerators, these are amines, and a whole group of compounds that are not included in any group. For example, these are derivatives of substances such as amines, ammonia and a number of others.

Diphenylguanidine, hexamethylenetetramine and many others are most often used in production. It is not uncommon for zinc oxide to be used to enhance the activity of accelerators.

In addition to additives and accelerators, an important role is played by environment. For example, the presence of atmospheric air creates unfavorable conditions for vulcanization at standard pressure. In addition to air, carbonic anhydride and nitrogen have a negative effect. Meanwhile, ammonia or hydrogen sulfide have a positive effect on the vulcanization process.

The vulcanization procedure gives rubber new properties and modifies existing ones. In particular, its elasticity improves, etc. The vulcanization process can be controlled by constantly measuring the changing properties. As a rule, the determination of tensile strength and tensile strength is used for this purpose. But these control methods are not accurate and are not used.

Rubber as a product of rubber vulcanization

Technical rubber is a composite material containing up to 20 components that provide various properties of this material. Rubber is produced by vulcanizing rubber. As noted above, during the vulcanization process, macromolecules are formed that ensure the performance properties of rubber, thus ensuring high rubber strength.

The main difference between rubber and many other materials is that it has the ability to undergo elastic deformations, which can occur at different temperatures, ranging from room temperature to much lower ones. Rubber significantly exceeds rubber in a number of characteristics, for example, it is distinguished by elasticity and strength, resistance to temperature changes, exposure to aggressive environments, and much more.

Cement for vulcanization

Cement for vulcanization is used for self-vulcanization operation, it can start from 18 degrees and for hot vulcanization up to 150 degrees. This cement does not contain hydrocarbons. There is also OTR type cement used for application to rough surfaces inside tires, as well as Type Top RAD and PN OTR series adhesives with extended drying time. The use of such cement makes it possible to achieve long service life for retreaded tires used on special construction equipment with high mileage.

Do-it-yourself hot vulcanization technology for tires

To perform hot vulcanization of a tire or tube, you will need a press. The welding reaction between the rubber and the part occurs over a certain period of time. This time depends on the size of the area being repaired. Experience shows that it will take 4 minutes to repair damage 1 mm deep, subject to the specified temperature. That is, to repair a defect 3 mm deep, you will have to spend 12 minutes of pure time. We do not take preparation time into account. Meanwhile, putting the vulcanization device into operation, depending on the model, can take about 1 hour.

The temperature required for hot vulcanization ranges from 140 to 150 degrees Celsius. To achieve this temperature there is no need to use industrial equipment. To repair tires yourself, it is quite acceptable to use household electrical appliances, for example, an iron.

Eliminating defects in a car tire or tube using a vulcanization device is a rather labor-intensive operation. It has many subtleties and details, and therefore we will consider the main stages of repair.

To provide access to the damage site, the tire must be removed from the wheel.
Clean the rubber near the damaged area. Its surface should become rough.
Blow off the treated area using compressed air. The cord that appears outside must be removed; it can be bitten off with wire cutters. Rubber must be treated with a special degreasing compound. Processing must be carried out on both sides, outside and inside.
On the inside, a pre-prepared patch of size should be placed on the damaged area. Laying begins from the side of the tire bead towards the center.
From the outside, pieces of raw rubber, cut into pieces of 10–15 mm, must be placed on the damaged site; they must first be heated on the stove.
The laid rubber must be pressed and leveled over the surface of the tire. In this case, it is necessary to ensure that the layer of raw rubber is 3–5 mm higher than the working surface of the chamber.
After a few minutes, using an angle grinder (angle grinder), it is necessary to remove the layer of applied raw rubber. If the bare surface is loose, that is, there is air in it, all applied rubber must be removed and the operation of applying rubber must be repeated. If there is no air in the repair layer, that is, the surface is smooth and does not contain pores, the part being repaired can be sent under preheated to the temperature indicated above.
To accurately position the tire on the press, it makes sense to mark the center of the defective area with chalk. To prevent the heated plates from sticking to the rubber, thick paper must be placed between them.

DIY vulcanizer

Any hot vulcanizing device must contain two components:

a heating element;
press.

To make your own vulcanizer you may need:

iron;
electric stove;
piston from internal combustion engine.

A do-it-yourself vulcanizer must be equipped with a regulator that can turn it off when it reaches operating temperature (140-150 degrees Celsius). For effective clamping, you can use an ordinary clamp.