Structural characteristics of cellulose esters with different degrees of substitution

In this article, structural characteristics of amorphous mono-, di-, and tri-substituted esters of cellulose have been studied. These esters were synthesized under homogenous conditions using anhydrides of various aliphatic acids. The specific gravity of the highly substituted samples was measured by a pycnometric method in the aqueous medium. To calculate the molar, Van der Waals, and free volumes, as well as the packing coefficient of amorphous esters, the method of additive contributions of partial volumes of atoms and atom groups in the volumes of polymers was used. Based on the molar volume, also values of specific gravity of cellulose esters were calculated. The coincidence of calculated and experimental characteristics was shown. In addition, the relationship between glass transition temperature and free volume was found for the esters of cellulose. The theoretical equations were derived, which provide predicting the structural characteristics of cellulose esters with different degrees of substitution.