微晶纤维素的醚化改性及其在淀粉膜中的应用

Etherification of Microcrystalline Cellulose for Application in Starch Films

为改善微晶纤维素(microcrystalline cellulose,MCC)在淀粉膜中的分散性,通过对MCC进行阳离子醚化改性,制得改性微晶纤维素(modified-microcrystalline cellulose,MD-MCC),并对其化学结构、结晶性、热稳定性和微观形貌进行表征。采用溶液流延法制得淀粉-微晶纤维素复合膜(淀粉-MCC,淀粉-MD-MCC),分别研究MCC和MD-MCC添加量对淀粉膜结构和性能的影响。结果表明,与MCC相比,MD-MCC的基本化学结构未改变,仍然保持纤维素的基本结构,但其结晶度和热稳定性略有降低,表面呈多孔结构。随着MCC和MD-MCC添加量的增加,淀粉膜的表面粗糙度增大,透光率和断裂伸长率降低,水接触角、水分含量和厚度增大,抗拉强度和水蒸气渗透系数先增加后减小。MD-MCC在淀粉膜中的分散性优于MCC,淀粉-MD-MCC复合膜的力学性能和阻水性能优于淀粉-MCC复合膜,其中MD-MCC添加量为5%时,复合膜具有最大的抗拉强度和阻水性能。

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.