Kinetics of polymerization processes

Берлин, А. А.; Vol'fson, S. A.; Enikolopian, N. S.

doi:10.1007/3-540-10217-5_4

Cited by 18 publications

(14 citation statements)

References 45 publications

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“…The problem of studying degradation of polymers by simulation is described in many works of both domestic (Berlin et al, 1978;Bryk, 1989;Koptelov and Milekhin, 2012) and foreign researchers (Ivanova et al, 2012;Browarzik and Koch, 1996;Ziff and McGrady, 1986). Studying of the polymer degradation process in a solution by modeling is described in a relatively small number of studies (Sivalingam and Madras, 2004;Sterling et al, 2001).…”

Section: Figure 1 Block Diagram Of the Controlling Objectmentioning

confidence: 99%

Control over the Process of Thermo-Oxidative Degradation of Polymers in a Solution

Хаустов¹,

Bitukov²,

Тихомиров³

et al. 2015

MAS

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The article discusses the process of low molecular rubber synthesis by the method of thermo-oxidative degradation as a controlled object. It was found that the control parameters affecting the degradation rate are the following: concentration of reaction initiator, temperature and mass concentration of the polymer. The main control parameters are the following: degree of degradation, quality of the resulting polymer and time of reaction. It was found that for effective control the process temperature and concentration of the initiator are to be stabilized in the vicinity of the predetermined value, and mass concentration is determined by dosage of initial components. In this case, the kinetics of the degradation process can be described as a linear function of time. I.e., the degree of degradation is linearly related to duration of reaction. Then, defining the initial quality of the polymer (its average molecular weight), the degradation process is performed till the time the predetermined value of degradation is reached.Since the initiator is consumed during the degradation, in order to stabilize its concentration, it is proposed to add the initiator into the reaction medium. We obtained a mathematical description that describes the kinetics of the process during continuous and divided feeding of the initiator, and dependency for calculating initiator feed rate. It has been shown that if the initiator is fed in a divided manner, linearity of degradation kinetics over time is ensured, which simplifies the technology of the process.Parameters of the approximating linear dependence of the kinetics of degradation have been determined. It has been shown that, even at the initial stage, the kinetics of degradation steadily tends to the linear asymptote. The asymptote's tilt angle depends on the constant of degradation rate (and consequently in the temperature of reaction) and on the initial concentration of the initiator. Degradation kinetics offset by the Y-axis depends on the initial molar concentration of the polymer. Thus, it is possible to control degradation rate by adjusting initial polymer concentration.

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Section: Figure 1 Block Diagram Of the Controlling Objectmentioning

confidence: 99%

Control over the Process of Thermo-Oxidative Degradation of Polymers in a Solution

Хаустов¹,

Bitukov²,

Тихомиров³

et al. 2015

MAS

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“…In [16], therefore, it is shown that "underheating" or "overheating" of the insulating sheath during fabrication of cables will result in a reduced degree of polymerization ϕ, destruction of the material, and other negative consequences in view their shorter or longer dwell time in the heating chamber with respect to the required values of t p . At a temperature of 373 K, therefore, vigorous processes of thermal decomposition begin to occur for the majority of rubbers, and combustion gases are released, whereupon the components of the rubber blend enter into exothermic reactions with oxygen [10][11][12]. The kinetic parameters of the polymerization must therefore be determined with maximum possible accuracy to ensure a high-quality article.…”

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confidence: 99%

“…"Complete polymerization" [10][11][12] means completion of the chemical process in the insulating layer prior to fulfi llment of the condition ϕ = 0.99-1.00 (ϕ is the degree of polymerization defi ning the degree of completion of the basic chemical reaction for the given initial value of ϕ 0 , and which characterizes the quality of the fi nal product). The time of completion of polymerization t p is the time after the lapse of which the degree of polymerization ϕ = 0.99-1.00 throughout the entire thickness (r 1 < r < r 2) of the sheath.…”

mentioning

confidence: 99%

“…Thermophysical characteristics (density, heat capacity, and thermal conductivity) of basic types of rubbers used in the cable industry are, as a rule, defi ned with an error of up to ±15%. The thermochemical characteristics are calculated with smaller (up to ±12%) errors [9][10][11].The objective of this study is to develop a prognostic model for theoretical analysis of the effect of errors generated in determining thermophysical and thermochemical characteristics of insulating materials on the integral parameters of their polymerization during manufacture of cable products.A heating-chamber-air-insulating-sheath−cable-core system was used for the numerical modeling (Fig. 1).…”

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confidence: 99%

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Effect of Errors of Determination of Thermochemical and Thermophysical Characteristics of Insulating Materials on Integral Process Parameters of their Polymerization

2015

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A prognostic model allowing for numerical evaluation of the effect of errors generated in determining basic thermochemical and thermophysical characteristics of insulating materials on integral parameters of their polymerization during fabrication of standard cable production is developed. It is established that even relatively small (15%) errors in numerical values of kinetic polymerization parameters may lead to signifi cant (up to 30%) deviations in the integral characteristics of this process (in contrast to the thermophysical characteristics of the insulating materials, the effect of which is suffi ciently moderated). The signifi cance of high accuracy of determination of kinetic parameters of polymerization typical of cable production is substantiated.Production of cable articles in Russia amounts to more than 200,000 tons per year [1]. At the present time, more than 2000 companies (including approximately 100 Russian companies) are involved with cable production on the world market [2]. Under competitive conditions, the high quality of an article is a basic consumer requirement. Here, the critical problem for the producers is a reduction in the net cost of the product by primarily lowering energy consumption for its production. This problem can be resolved by the use of scientifi cally backed processes.Studies [3][4][5][6][7][8] and others are devoted to the mechanical, thermophysical, thermochemical, and other characteristics of standard insulating materials. Various modifi cations of rubbers are employed for fabrication of cable production. Thermophysical characteristics (density, heat capacity, and thermal conductivity) of basic types of rubbers used in the cable industry are, as a rule, defi ned with an error of up to ±15%. The thermochemical characteristics are calculated with smaller (up to ±12%) errors [9][10][11].The objective of this study is to develop a prognostic model for theoretical analysis of the effect of errors generated in determining thermophysical and thermochemical characteristics of insulating materials on the integral parameters of their polymerization during manufacture of cable products.A heating-chamber-air-insulating-sheath−cable-core system was used for the numerical modeling (Fig. 1). The statement analyzed for the problem of heat and mass exchange is the development of a model presented in [12]: in contrast to this model, movement of the article within the heating chamber and its lack of a seal at the inlet and outlet are considered.During the course of the modeling, it was assumed that the cable consists of core 1 and sheath 2. The article with an initial temperature T 0 and constant velocity w c moves through the heating chamber. The sheath is heated to a signifi cantly

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Re-examination of free-radical copolymerization kinetics

Fukuda

Inagaki

1985

Makromol. Chem.

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The velocity of free-radical copolymerization is as yet not comprehensively understood in terms of the elementary processes of propagation and termination. A prevailing view of this classical subject may be that the propagation process is. in most cases, correctly described by the simple mechanism embodied by the "terminal model", whereas the termination process involves complexity, still remaining to be interpreted. However, very recent experiments on styrenelmethyl methacryl ate and p-chlorostyrene/methyl acrylate copolymerizations, in which both the steady-and nonsteady-state polymerizations were observed to examine the two processes separately, indicate that the fact may be just the reverse: it is the propagation step that need be re-interpreted, while the termination step is well described by simple models such as the North "diffusion model".

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Kinetics of polymerization processes

Cited by 18 publications

References 45 publications

Control over the Process of Thermo-Oxidative Degradation of Polymers in a Solution

Control over the Process of Thermo-Oxidative Degradation of Polymers in a Solution

Effect of Errors of Determination of Thermochemical and Thermophysical Characteristics of Insulating Materials on Integral Process Parameters of their Polymerization

Re-examination of free-radical copolymerization kinetics

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