Study on Esterification Characteristics of TEMPO-Oxidized Cellulose

Abstract

Oxidized cellulose acetate (OCA) with carboxylic acid group on C-6 position of glucose is a kind of biodegradable functional materials which can be dissolved in organic solvents. First, cellulose was oxidized with TEMPO (2, 2, 6, 6-tetramethyl-piperidyl-1-oxyl) oxidation system, and then OCA was produced via esterification by reacting the oxidized cellulose with acetic anhydride. The influence factors such as carboxylic content of oxidized cellulose, reaction temperature, reaction time, and concentration of acetic anhydride on degree of substitution (DS) of acetyl group and intrinsic viscosity ([η]) of OCA were investigated. The result revealed that the DS of acetyl group can be increased effectively from 2.61 to 2.74 by increasing reaction temperature from 50°C to 80°C, and from 2.58 to 2.72 by prolonging reaction time from 40min to 180min, but the [η] of the product decreased at the same time. An increase in concentration of acetic anhydride led to an increase in DS and [η] of OCA. As the carboxyl content increased from 0.383 mmol/g to 0.797 mmol/g, the DS of acetyl group decreased from 2.81 to 2.73. That result revealed the carboxyl content also has a great influence on the esterification characteristics.