Preparation and characterization of arabinoxylan esters and arabinoxylan ester/cellulose ester polymer blends

A water-soluble, high molecular weight arabinoxylan was isolated from corn fiber. This arabinoxylan was a highly branched and complex polysaccharide composed of xylose, arabinose, galactose, glucuronic acid and glucose. Treatment of this arabinoxylan with a C2–C4 aliphatic anhydride using methanesulfonic acid as a catalyst or trifluoroacetic anhydride as a promoter rapidly and conveniently provided the corresponding arabinoxylan esters. The arabinoxylan esters were isolated as high molecular weight, amorphous solids with glass transition temperatures ranging from 61 to 138 °C. The arabinoxylan esters are soluble in a range of solvents and can tolerate significant amounts of water as a co-solvent. The arabinoxylan esters are thermally stable to near 200 °C but undergo significant and rapid thermal degradation when heated above the onset of thermal degradation. Optically clear films of arabinoxylan acetate and cellulose acetate were prepared by casting films from common solvents. Thermal analysis of these blends indicated that the blends were comprised of a single phase or two phases depending upon the composition of the solvent, solvent concentration, and rate of evaporation of the solvent.