Fatty acid derivatives of cellulose for barrier applications

Birch kraft pulp has been tested for its appropriateness to be transformed into cellulose films by acylation in homogenous media (LiCl/DMAc) with two saturated fatty acid chlorides containing a chain of 10 and 16 carbon atoms. The FTIR spectra of the cellulose esters with 6 equivalents of acyl chlorides represent a significant decrease on the intensity of hydroxyl groups indicating that a number of OH groups were replaced. Novel 31P-NMR method was carried out to determine degree of substitution. The highest DS value (2.6) was obtained from the cellulose esters modified by palmitoyl chloride with a mole ratio af acylating agent to anhydroglucose units (AGU) of 6. The resultant esters were converted to films and hydrophobicity of the materials was determined. The water vapor transmission rate (WVTR) decreased with increasing chain length of the substituent, while water contact angle increased.