Effects of Coagulation Conditions on the Properties of Regenerated Cellulose Films Prepared in NaOH/Urea Aqueous Solution

Abstract

Effects of coagulant components and coagulation conditions on the structure and properties of regenerated cellulose (RC) films prepared from cellulose in 7.5 wt % NaOH/11 wt % urea aqueous solution were investigated by 13C NMR, X-ray diffraction, scanning electron micrograph, tensile testing, etc. The uniform design method based on theoretical accomplishments in the number-theoretic method was used to optimize the coagulation conditions of H2SO4 aqueous solution with various concentrations (from 1 to 15 wt %), time (from 1 to 15 min), and temperature (from 25 to 55 °C). Moreover, a series of RC films coagulated, with 5 wt % H2SO4/Na2SO4, Na2SO4, HOAc, and (NH4)2SO4, respectively; different concentrations (from 1 to 20 wt %) and times (from 1 to 20 min) at 25 °C were also investigated. The results indicated that the optimal coagulant concentrations and coagulation times of the RC films are 5 wt % H2SO4 for 5 min, 5 wt % H2SO4/5 wt % Na2SO4 for 5 min, 5 wt % Na2SO4 for 15 min, 3 wt % HOAc for 5 min, and 5 w...