凝固浴组成对NMMO法纤维素膜形貌的影响

为实现对分离用纤维素膜形貌的控制,采用NMMO法,分别以水、甲醇、乙醇和由它们配制的双组分溶液为凝固浴,制备了纤维素膜,观察了干膜的表面和断面形貌,测定了湿膜的孔结构参数,在对比基础上分析了干膜中微孔的形成过程与机制,探讨了纤维素结晶尺度与湿膜平均孔径的相关性和影响因素.研究表明,不同凝固浴制备出的纤维素膜在干态形貌上差别明显.纤维素膜的湿态孔隙率基本不受凝固浴组成影响,而干态下的致密区域在水溶胀后呈现多孔结构,对湿膜平均孔径影响很大.通过改变凝固浴组成,可分别或协同地调控纤维素膜的干态或湿态结构.

Influence of Coagulation Bath on Morphology of Cellulose Membranes Prepared by NMMO Method

In order to realize the control on morphology of cellulose membrane used for separation, the cellulose membranes were prepared by NMMO method with using water, methanol, ethanol and their binary solution as coagulation bath. The morphology of surface and cross section of dry membrane were observed. The pore structure parameters of wet membrane were determined. By comparison, the process and mechanism of pore forming in dry membrane was suggested, and the relativity and influence factors of cellulose crystal size and average pore diameter in wet membrane was discussed. The results show that the morphology of dry membrane is varied with coagulation bath clearly, while the porosity of wet membrane is almost constant. The compact region in dry membrane can appear porous structure when swelling by water. These pores have virtual effect on the average pore diameter of wet membrane. Through changing the composition of coagulation bath, the microstructure of cellulose membrane at dry and wet environment can be adjusted separately or synergistically,