Thermodynamics of cellulose esterification

This research discusses the standard enthalpies of the combustion and formation of cellulose acetates and nitrates. In addition, the standard enthalpies of cellulose esterification were calculated.  For cellulose acetates, it was shown that an increase in the degree of substitution (SD) contributes to enhancing both the exothermic enthalpy of the formation and the exothermic enthalpy of the reaction. It was concluded that the feasibility of the acetylation reaction of cellulose, especially to di- and triacetates, is determined mainly by the exothermic enthalpy. The experiments with nitrocelluloses have shown that with an increase in SD, the enthalpies of combustion and formation become less exothermic. When cellulose is nitrated with dilute nitric acid to SD < 1.5, the enthalpy of the nitration reaction is endothermic. Thus, to implement the nitration process of cellulose with a dilute reagent, the contribution of the entropy to the Gibbs potential of this reaction is necessary. On the other hand, when cellulose is nitrated with more concentrated nitric acid to SD >1.5, the reaction enthalpy becomes exothermic. In this case, the feasibility of the cellulose nitration process will be determined mainly by the exothermic reaction enthalpy. As the degree of substitution increases, the specific gravity of cellulose acetates decreases, while that of nitrocelluloses increases. From experimental values of specific gravity, the degree of substitution of cellulose derivatives was calculated.