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Influence of Temperature–Time Parameters and System Composition on Kinetics of Acetalization Reaction in Preparation of Polyvinyl Formal Foam from Polyvinyl Alcohol Solutionстатья
- Авторы: Akimova A.A., Lomovskoy V.A., Simonov-Emelyanov I.D.
- Журнал: Theoretical Foundations of Chemical Engineering
- Том: 56
- Номер: 6
- Год издания: 2022
- Издательство: Maik Nauka/Interperiodica Publishing
- Местоположение издательства: Russian Federation
- Первая страница: 982
- Последняя страница: 987
- Оригинальные версии: ВЛИЯНИЕ ТЕМПЕРАТУРНО-ВРЕМЕННЫХ ПАРАМЕТРОВ И СОСТАВА СИСТЕМЫ НА КИНЕТИКУ РЕАКЦИИ АЦЕТАЛИРОВАНИЯ ПРИ ПОЛУЧЕНИИ ПЕНОПОЛИВИНИЛФОРМАЛЯ ИЗ РАСТВОРА ПОЛИВИНИЛОВОГО СПИРТА
- DOI: 10.1134/s0040579522060021
- Аннотация: The influence of the temperature–time parameters and the composition of the reaction system on the kinetics of the acetalization reaction during the preparation of polyvinyl formal foam from aqueous solutions of polyvinyl alcohol is studied. The mechanism of the acetalization reaction and the equations are provided to describe the transformation of polyvinyl alcohol into polyvinyl formal in the presence of formaldehyde and acid catalysts of the homogeneous and heterogeneous reaction regions. We show that the degree of conversion by the acetalization reaction remains almost unchanged (0.85–0.87) with increase in concentration of polyvinyl alcohol, but the time to reach the maximum conversion increases by a factor of ~2.5 (from 11 to 26 min). The optimal concentrations of formaldehyde and sulfuric acid (catalyst) for the kinetics of the acetylation of polyvinyl alcohol in aqueous solution are found: the concentration of formaldehyde C0a is 3.3 mol/L and that of sulfuric acid C0H2SO4 is 3.5 mol/L. An increase in temperature leads to an increase in the rate of the acetalization reaction and a decrease in the time for the synthesis of polyvinyl formal from aqueous solutions of polyvinyl alcohol. We show that it is inexpedient to increase the synthesis temperature higher than 50°C. The optimal temperature to obtain polyvinyl formal from aqueous solutions of polyvinyl alcohol is considered as ~40–45°С. The data obtained prove that the acetalization reaction is completed within the time that provides the stability of the foam from aqueous solution of polyvinyl alcohol (at least 20–30 min).
- Добавил в систему: Абхалимов Евгений Владиленович