4种方法从葎草中制备的纳米纤维素性能

以葎草(Humulus scandens)为原料,分别采用4种方法制备了纳米纤维素,分别为硫酸水解所制得的纤维素纳米晶须(sulfuric acid-cellulose nanocrystals,S-CNC)、盐酸水解法制得的纤维素纳米晶须(hydrochloric acid-cellulose nanocrystals,H-CNC)、大功率超声法制得的纤维素纳米纤维(ultrasound-cellulose nanofibrils,U-CNF)和高速搅拌法制得的纤维素纳米纤维(stirring-cellulose nanofibrils,S-CNF),然后采用透射电子显微镜(TEM)、傅利叶红外光谱仪(FTIR)、X射线衍射仪(XRD)、热重分析仪(TGA)分别对4种纤维素的形态、化学结构、晶体结构、热稳定性能进行了表征。结果表明,硫酸水解法和盐酸水解法制备的纳米纤维素呈棒状,大功率超声法和高速搅拌法制备的纳米纤维素呈网状;S-CNC具有最高的结晶度(70.05%),而S-CNF结晶度最低(58.94%);4种纳米纤维素均保持着纤维素Ⅰ型结构;U-CNF的热稳定性最佳,开始分解温度为261.9℃,而S-CNC的热稳定性最差,初始分解温度为217.8℃。

Comparative analysis of nanocellulose from Humulus scandens stems using four isolation methods

Sulfuric acid-cellulose nanocrystals(S-CNC),hydrochloric acid-cellulose nanocrystals(H-CNC),ultrasound-cellulose nanofibrils(U-CNF)and stirring-cellulose nanofibrils(S-CNF)were successfully isolated from Humulus scandens stems(HSS)using sulfuric acid hydrolysis,hydrochloric acid hydrolysis,high power ultrasonic and high stirring,respectively.The morphology,chemical structure,crystal structure and thermal stability were characterized using scanning electron microscopy,transmission electron microscopy,Fourier transform infrared spectroscopy,X-ray diffraction patterns and thermal gravimetric analysis.The results suggested that the S-CNC and H-CNC prepared by acid hydrolysis had short rod-like shapes,while the U-CNFs and S-CNFs had reticular shapes.The S-CNC has the highest crystallinity(70.05%)while the S-CNF had the lowest crystallinity of the four kinds of nanocellulose;all maintained cellulose Ⅰ structure.The U-CNF had the best thermal stability with initial decomposition temperature of 261.9 ℃,but the S-CNC was the worst with the initial decomposition temperature of 217.8 ℃.