Abstract: In order to improve the dispersibility of microcrystalline cellulose (MCC) in starch (ST) films, modified microcrystalline cellulose (MD-MCC) was prepared by cationic etherification of MCC, and its chemical structure, crystallinity, thermal stability and micromorphology were characterized. The starch/cellulose composite films ST-MCC and ST-MD-MCC were prepared by the solution casting method. The effects of different amounts of MCC and MD-MCC on the physicochemical properties of starch films were investigated. The results showed that the basic chemical structure of MD-MCC was similar to that of MCC, and the basic structure of cellulose was still maintained, but the crystallinity and thermal stability slightly decreased, with porous structures appearing on the surface. With the increase of MCC and MD-MCC concentrations, the surface roughness of the composite films increased, the light transmittance and elongation at break decreased, the water contact angle, moisture content and thickness rose, and the tensile strength and water vapor permeability first increased and then decreased. MD-MCC was dispersed better in the composite films than MCC. The tensile strength and water resistance of ST-MD-MCC films were better than those of ST-MCC films. ST-5% MD-MCC had the maximum tensile strength and the best water resistance.

Key words: starch films; microcrystalline cellulose; etherification; dispersibility; properties