Preparation and characterization of cellulose nitrate-acetate mixed ester fibers

Cellulose nitrate-acetate mixed esters (CNA) were synthesized by nitration of cellulose diacetate, using HNO3/H2SO4 as nitration agent. The CNA structures were confirmed and analyzed by IR and 1H NMR. A decrease in molecular weight and an increase in nitrate group content were observed with increasing H2SO4 ratio and reaction time. The highest degree of nitrate substitution, 9.2%, for CNA was achieved with the reaction time of 6h in concentrated HNO3. Increasing HNO3 ratio in nitration media resulted in more thermally stable CNA. CNA fibers were prepared by altering the polymer concentration from 15 to 30% in an 85:15 (w/w) acetone:water solvent. The electrospun CNA fibers were characterized by SEM to investigate the influence of different NO2% on fiber formation, diameters and architectures.