Abstract: The new cellulose acetate of high degrees of substitution and crystallinity was prepared by acetylation of microcrystalline cellulose(MCC) in the heterogeneous system through distillation under reduced pressure.The degrees of substitution and crystallinity of the cellulose were 1.85 and 67%,respectively.The characteristics of this cellulose acetate was analyzed by FT-IR,X-ray and TGA.The results show:of high degree of substitution,the cellulose acetate prepared in heterogeneous system not only has much higher crystallinity than those prepared in quasi-homogeneous system,but also keeps the crystal form of cellulose I and has high thermal stability.

Key words: high crystallinity, high degree of substitution, cellulose acetate