纤维素纳米晶体制备工艺优化的研究

以微晶纤维素(MCC)为原料经硫酸水解制备纤维素纳米晶体(CNC)。采用单因素法结合正交试验系统地研究了硫酸质量分数、反应温度和反应时间对纤维素纳米晶体得率以及平均粒径的影响，并通过扫描电镜(SEM)、原子力显微镜(AFM)、X射线衍射仪(XRD)、纳米激光粒度仪对CNC的性能进行了表征，揭示了酸水解制备CNC的机理。结果表明：CNC制备的最佳工艺参数为硫酸质量分数64%、反应温度45 ℃、反应时间90 min，在此条件下CNC的得率为24.6%，粒径为204.8 nm。CNC水悬浮液呈一种稳定的淡蓝色胶体状态，其微观形貌比较规整，呈短棒状，直径约10~20 nm，长度在150~300 nm之间；XRD结果显示CNC的晶型为纤维素Ⅰ型，结晶度为80.2%。

Optimization of Preparation Process of Cellulose Nanocrystals

Cellulose nanocrystals(CNC) were prepared from microcrystalline cellulose(MCC) by sulfuric acid hydrolysis. The effects of sulfuric acid mass fraction, reaction temperature and reaction time on the yield and average particle size of cellulose nanocrystals were studied by single factor method combined with orthogonal test. The performance of CNC was characterized by scanning electron microscopy(SEM), atomic force microscopy(AFM), X-ray diffractometer(XRD) and nano-laser particle size analyzer, and the mechanism of acid hydrolysis to prepare CNC was revealed. The results showed that the optimum process parameters of CNC preparation were sulfuric mass fraction 64%, reaction temperature 45 ℃ and reaction time 90 min. Under these conditions, the yield of CNC was 24.6% and the particle size was 204.8 nm. The CNC aqueous suspension was a kind of stable light blue colloidal state, and its microscopic morphology was relatively regular, which was short rod-shaped, with diameter of about 10-20 nm and length between 150-300 nm; XRD results showed that the crystal form of CNC was cellulose type Ⅰ, and the crystallinity was 80.2%.