Effects of coagulants on porous structure of membranes prepared from cellulose in NaOH/urea aqueous solution
Effects of coagulants on porous structure of membranes prepared from cellulose in NaOH/urea aqueous solution
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DOI：
10.1016/j.memsci.2005.07.048
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发表时间：
2006-08
影响因子：
9.5
通讯作者：
Y. Mao;Jinping Zhou;J. Cai;Lina Zhang
中科院分区：
文献类型：
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作者：
Y. Mao;Jinping Zhou;J. Cai;Lina Zhang
以NaOH/尿素水溶液中的纤维素为原料，分别与H2SO4、HOAc、H2SO4/Na2SO4、Na2SO4、（NH4）2SO4、H2O、C2H5OH和（CH3）2CO混凝，制备了一系列再生纤维素膜。采用扫描电子显微镜、原子力显微镜、流速法、拉伸试验等对膜的形貌、透水性和物理性能进行了研究。不同混凝剂制备的膜自由表面孔径为265 ~ 730nm，内部孔径为173 ~ 266nm，结构相对均匀。酸性混凝剂凝固后的膜孔径较小，分布较窄。而有机混凝剂混凝后的膜孔径较大，分布较广。与有机混凝剂相比，用酸性和盐溶液混凝的膜具有更好的拉伸强度和断裂伸长率。本研究制备的膜具有比用氧化镁和粘胶制备的膜更大的平均孔径和更高的透水性。纤维素凝胶中纤维素-贫相的成核和生长导致纤维素基质中形成多孔结构，孔隙大小主要与非溶剂与溶剂之间的扩散速率有关。本研究为通过选择合适的混凝剂制备具有不同孔径和物理性质的多孔膜提供了一条有希望的途径。
A series of regenerated cellulose membranes was prepared from cellulose in NaOH/urea aqueous solution by coagulating with various coagulants including H2SO4, HOAc, H2SO4/Na2SO4, Na2SO4, (NH4)2SO4, H2O, C2H5OH and (CH3)2CO, respectively. The morphology, water permeability and physical properties of the membranes were investigated by scanning electron micrograph, atom force micrograph, flow rate method, tensile test, etc. The membranes prepared from various coagulants possessed a pore size range from 265 to 730nm in the free surface, and relatively uniform structure having pore size from 173 to 266nm in the inner. The membranes coagulated with acidic coagulant exhibited the relatively small pore size and narrow distribution. On the contrary, the membranes coagulated with organic coagulant possessed the relatively large pore size and wide distribution. All of the membranes coagulated with acidic and salt aqueous solution exhibited the better tensile strength and elongation at break than that with organic coagulant. The membranes in this work possessed larger mean pore size and higher water permeability than those prepared from the cuoxam and viscose. The nucleation and growth of the cellulose-lean phase in the cellulose gel resulted in the formation of porous structure in the cellulose matrix, and the pore size was mainly related to the diffusion rate between nonsolvent and solvent. This work provided a promising way to prepare porous membranes having different pore size and physical properties by choosing the proper coagulants.