Kinetic Studies on the Crosslinking of Cellulose Membranes with Polyfunctional Epoxides in Aqueous Solution

Abstract

The kinetic parameters of the crosslinking reaction between cellulose membranes and an aqueous solution of 1,4‐butanediol diglycidyl ether were determined by dynamic differential scanning calorimetry (DSC) experiments. The reaction shows an autocatalytic behavior which was described by an extended Prout‐Tompkins equation. Conversion curves were simulated based on these results and function as a basis for the design and improvement of continuous processes used for the industrial production of crosslinked cellulose membranes.

Kinetic Parameters of the Cross‐linking Reaction of Cellulose Membranes with Bifunctional Epoxides

“…All dynamic DSC measurements were processed as described in 7 under consequent use of an extended Prout‐Tompkins equation as reaction model f ( x ). Thus, all four apparent kinetic parameters required to simulate the measured data, i.e., activation energy E A , pre‐exponential factor A , reaction order n and grade of autocatalysis a , were evaluated the same way.…”

“…3 in the experimental section. It was also observed that the curing reaction of a pure cross‐linking solution in absence of a cellulose membrane exhibits very similar kinetic parameters at high concentrations of the cross‐linking agent 7, indicating that the side reactions such as hydrolysis or oligomerization always play a major role in this reaction system. When evaluating the cross‐linking kinetics based on dynamic DSC measurements, all possible reaction paths including all side reactions will take place simultaneously.…”

“…The method used in these experiments and typical DSC curves obtained from the measurements were already described and shown in detail in 7, therefore no additional DSC curves obtained in this study will be displayed here. For the dynamic DSC measurements performed in the context of this work, heating rates of 2.5, 5.0 and 10 K min −1 were used.…”

“…In order to design such a continuous cross‐linking process and to find appropriate reaction conditions for the heterogeneous two‐phase system a detailed kinetic analysis of the cross‐linking reaction is required, especially regarding the composition of the cross‐linking solution in terms of concentration of cross‐linking agent and catalyst. It was shown in a previously published paper that this kinetic examination can be performed based on dynamic DSC experiments assuming that the degree of conversion is proportional to the area of the exothermal peak of the cross‐linking reaction 7, 10. The obtained data can be pre‐evaluated with model‐free methods such as Friedman analysis or Ozawa‐Flynn‐Wall analysis.…”

“…Based on this initial information, a suitable kinetic model can be fitted to the experimental data. A very comprehensive description of the theoretical background is provided, e.g., by 10 or 11, and an overview of the evaluation of the kinetic parameters of the system at hand using this experimental approach was already provided in 7.…”