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

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.