不同形态的纳米晶纤维素的制备及其性能研究

Effect of Hydrolysis Time on the Preparation and Properties of Cotton Cellulose Nanocrystal

用硫酸酸解棉短绒制备纳米晶纤维素(CNC),并通过改变酸解时间得到不同形态的CNC。采用透射电子显微镜(TEM)、红外光谱分析(FT-IR)、X射线衍射(XRD)、Zeta电位分析、热重(TGA)、流变行为分析对CNC进行结构、形态和性能表征。结果表明,随着酸解时间的延长,糖苷键断裂越多,得到的CNC由棒状的形态变成球状的形态;酸解时间越短,CNC表面的负电荷越少,而粒子分散得到的悬浮液粘度越大,具有更大的储能模量(G’)和损耗模量(G’’),显示出弹性凝胶状行为。此时,粒子结晶度较大,热稳定性较好,CNC-45对聚乙烯醇基体的增强效果较好。

Different morphology cellulose nanocrystals （CNC） were extracted from cotton fiber using sulfuric acid with controlled hydrolysis time. The structure-morphology-property relationships for cellulose nanocrystals were investigated by TEM, FT-IR, XRD, Zeta-potential measurements, Rheological measurements and TGA. As the hydrolysis time increased, more glycoside bonds of CNC were broken and the morphology of CNC transformed from rod-like shape to spherical shape. The CNC suspension with short hydrolysis time had less negative charged of the surface of CNC, higher storage modulus （G′） and loss modulus （G″）, and higher viscosity than the others with long hydrolysis time, indicating elastic gel-like behavior of CNC suspension. The results also indicated that the degree of crystallinity and the thermal stability of CNC decreased as the reaction of time increased. Polyvinyl alcohol （PVA） reinforced with CNC-45 displayed the higher tensile strength.