炭基磷钨酸催化制备纳米纤维素的研究

Preparation and Characterization of Nanocrystalline Cellulose Catalyzed by Carbon-Based Phosphotungstic Acid

采用炭基磷钨酸在超声波辅助作用下水解微晶纤维素（MCC ），制备得到纳米纤维素晶体（NCC）。采用透射电子显微镜（TEM）、X射线衍射仪（XRD）、傅里叶变换红外光谱仪（FTIR）和热分析仪（TGA ）等对所制备N C C的形貌、晶体结构、光谱性质和热稳定性进行分析。结果表明：制备的NCC呈棒状，直径和长度主要分布在12～79 nm和146～862 nm，样品仍属于纤维素Ⅰ型，结晶度为76．1％；FTIR分析可知，纳米纤维素晶体仍然具有纤维素的基本化学结构；TGA分析表明，纳米纤维素晶体热分解温度为300℃，初期热稳定性低于微晶纤维素。与常规酸水解方法相比，该方法在制备过程中可省去脱酸过程，具有对设备腐蚀性小、环保等优点。

Nanocrystalline cellulose （NCC）was prepared by ultrasonic-assisted hydrolysis of microcrystal-line cellulose （MCC ） with carbon-based phosphotungstic acid as the catalyst.The morphological,crystal structure,spectrum properties and thermal stability properties of NCC were respectively analyzed by transmis-sion electron microscopy （TEM）,X-ray diffraction （XRD ）,Fourier transformation infrared spectroscopy （FTIR）,and thermographic analyzer （TGA）.The results indicated that NCC was rod-like with diameter ran-ging around 10 -100 nm and length ranging between 200 -800 nm.The XRD pattern showed that the NCC still kept with the typeⅠcellulose structure,and its crystallinity was 76 .1%.The FTIR analysis showed that NCC was still with the basic chemical structure of cellulose.The results of TGA analysis demonstrated that the thermal decomposition temperature of NCC was 300℃,whose primary thermal stability of NCC was lower than that of MCC.Compared with the conventional acid hydrolysis,the new preparation approach of NCC could a-void the acid removing process,and it possessed the advantages of low corrosion to equipments,and less pollu-tion to the environment and the like.