纳米纤维素晶须的表面醋酸酯化改性及复合材料的力学性能  

Surface Acetylation of Cellulose Nanowhiskers and Its Reinforcing Function in Cellulose Acetate

作　　者：杨振钰[1] 王文俊[1] 邵自强[1] 李永红[1] 

机构地区：[1]北京理工大学材料科学与工程学院,北京100081

出　　处：《高等学校化学学报》2013年第4期1021-1026,共6页Chemical Journal of Chinese Universities

摘　　要：采用硫酸水解法制备纳米纤维素晶须,再以冰醋酸为分散介质,浓硫酸为催化剂,醋酸酐为酯化剂对纳米纤维素晶须进行不同程度醋酸酯化改性,得到醋酸酯化的纳米纤维素.采用红外光谱(FTIR)、X射线光衍射(XRD)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)等手段对改性产物进行分析和表征.结果表明,改性纳米纤维素晶须中醋酸酯基的平均取代度过小或过大时均不适宜用作复合材料的增强相.当改性纳米纤维素晶须中醋酸酯基的平均取代度为0.05时,醋酸酯化反应只发生在纳米纤维素晶须的表面.此时,晶须能在丙酮中稳定悬浮,表现出流动双折射现象,并保持了改性前纳米纤维素晶须的棒状形态和高结晶度.将这种改性后的纳米纤维素晶须作为增强相与醋酸纤维素通过溶液浇铸法制成纳米复合膜,结果显示,与空白醋酸纤维素膜相比,添加改性纳米纤维素晶须后,纳米复合膜的拉伸强度、杨氏模量和断裂伸长率都得到了提高.在玻璃化转变区间纳米复合膜储能模量的降低幅度小于空白膜.Cellulose nanowhiskers were prepared by sulfuric acid hydrolysis, then they were chemically modi- fied by acetylation to obtain aeetylated cellulose nanowhiskers（ACNW）. The chemical and morphology struc- ture of the ACNW were examined with Fourier transform infrared spectroscopy（FTIR）, X-ray diffraction （XRD） , transmission electron microscopy （TEM） and X-ray photoelectron spectroscopy （ XPS ）. ACNW with too low or too high degree substitute （DS） were not suitable for fillers in nanocomposites. When the DS of ACNW was 0. 05, the acetylation modification limited only on the surface of the cellulose nanowhiskers, and the modified cellulose nanowhiskers preserved their original rod-like structure and high degree of crystalliza- tion. Cellulose acetate （CA） nanocomposites were prepared using ACNW as fillers by a casting/evaporation technique, and the effect of ACNW contents on the tensile properties of the CA matrix was studied. The ten- sile strength, Young＇ s modulus, and strain at break of all CA nanocomposites exhibited simultaneous increase in comparison with neat CA matrix. The storage modulus of CA nanocomposites after temperature of glass tran- sition （ Ts） was higher than the neat CA matrix.

关 键 词：纳米纤维素晶须 醋酸酯化 醋酸纤维素 纳米复合材料 拉伸性能 

分 类 号：O636.11[理学—高分子化学]