目的 为了制备纤维素Ⅱ晶型的高长径比纳米纤维素，并与纤维素Ⅰ、Ⅰ/Ⅱ晶型的纳米纤维素进行性能的对比。方法 文中以玉米秸秆纤维为原料，通过化学处理和机械研磨法制得纤维素Ⅰ、Ⅰ/Ⅱ、Ⅱ晶型的纳米纤维素，分别记为CNF–Ⅰ、CNF–Ⅰ/Ⅱ、CNF–Ⅱ。结果 透射电镜观察表明，CNF–Ⅰ、CNF–Ⅰ/Ⅱ和CNF–Ⅱ的直径分布范围为5～50 nm、5～60 nm和5～80 nm。紫外可见分光光度计测试表明，3种CNF薄膜都具有良好的透光率。力学测试表明，CNF–Ⅰ膜的拉伸强度(184.7 MPa)较高，而CNF–Ⅱ膜则韧性较好，具有更高的断裂伸长率(12.5%)。结论 在CNF–Ⅱ的制备中，脱木素技术对晶型转化(纤维素Ⅰ晶型转化为纤维素Ⅱ晶型)和后续机械纳米化影响较大;通过化学处理结合机械研磨法可制得高长径比的CNF–Ⅱ，一次研磨法产率高达80%，工艺简便，操作难度和制取成本较低。

The work aims to prepare cellulose Ⅱ nanofibers with high aspect ratio, and compare their properties with those of cellulose Ⅰ, Ⅰ/Ⅱ nanofibers. Cellulose Ⅰ, Ⅰ/Ⅱ and Ⅱ nanofibers (CNF-Ⅰ, CNF-Ⅰ/Ⅱ and CNF-Ⅱ, respectively) were prepared by chemical treatment and mechanical grinding with corn straw as the raw material. Transmission electron microscopy showed that the diameter distribution range of CNF-Ⅰ, CNF-Ⅰ/Ⅱ and CNF-Ⅱ were about 5~50 nm, 5~60 nm and 5~80 nm, respectively. Ultraviolet-visible spectrophotometer test exhibited that the three CNF films all had good transmittance. Mechanical tests showed that CNF-Ⅰ film had higher the tensile strength (184.7 MPa), while CNF-Ⅱ film was more ductile and had higher elongation at break (12.5%). During preparation of CNF-Ⅱ, the delignification technology has a great influence on the crystal transformation (from cellulose Ⅰ to cellulose Ⅱ) and subsequent mechanical nano-fibrillation. CNF-Ⅱ with high aspect ratio can be prepared by chemical treatment combined with mechanical grinding method. The yield rate of once grinding is up to 80%. It has the advantages of simple process, easy operation and low production cost.