中文摘要：

纳米纤维素是一种新型高分子功能材料，具有独特的结构和优异的性能。本文采用加热析出法制备得到纳米纤维素（HNC）的直径为10—100nm，XRD、FTIR、TG等测试结果表明HNC在制备过程中，纤维素晶体由I型转化为II型，但分子结构未发生变化。通过对纳米纤维素分散液进行压滤制备得到纳米纤维素膜（HNCF），其透光率为89．7％，抗拉强度为84．9MPa，杨氏模量为4933．6MPa。并进一步揭示了加热析出法制备纳米纤维素的机理。

英文摘要：

Nanocellulose （ HNC ） is a novel functional polymer material with unique structure and excellent performance. HNC with a width between 10 - 100 nm was prepared by heating cellulose solution directly. The structure of HNC did not change during the preparation process, but the crystal form transferred from Cellulose I to Cellulose II, which was validated by the results of XRD, FFIR, and thermal performance test. The nanocellulose film （HNCF） obtained by filtering the nanocellulose solution, which showed a transmittance of 89.7% , tensile strength of 84. 9 MPa and Young＇s modulus of 4933.6 MPa, respectively. The convincing mechanism model explaining the function of sodium hydroxide and urea was revealed.