摘要
在纤维素-7% NaOH-12%尿素水溶液体系中加入少量无机盐诱导和促进体系形成凝胶,研究了不同种类和用量的无机盐对凝胶形成过程的促进作用,促进能力依次为:阴离子相同时,钾盐>钠盐>锂盐;阳离子相同时,氯盐>溴盐>硝酸盐.无机盐浓度越高对凝胶形成的促进作用越明显.在此基础上结合溶剂置换和超临界CO2干燥技术,提出了无机盐诱导凝胶法制备纤维素气凝胶的新工艺,用SEM、氮吸附仪和压汞仪对所制气凝胶材料进行了结构表征,材料具有介孔到大孔范围的多孔结构,介孔的比表面积为284m2/g,孔体积为2.0cm3/g,平均孔径为20.5nm;大孔的孔体积为13.95cm3/g,平均孔径为0.732μm,孔隙率达91%.
For the cellulose-7% NaOH-12% urea aqueous solution, adding inorganic salts can induce and accelerate its gelation process. The inorganic salts show a remarkable accelerating effect on the gelation with the sequences as K^＋〉Na^＋〉Li^＋ for cations and Cl^-〉Br^-〉NO3^- for anions. For all kinds of salts used, the gelation rate increases with the increase of the salt dosage. Based on this result, a new preparation method of cellulose aerogels has been proposed using inorganic salt-induced gelation followed by solvent exchange and supercritical CO2 drying. According to the SEM, N2 adsorption and mercury intrusion measurements, the porous structure of cellulose aerogel made through salt-induced gelation is characterized as follows： in the mesopore range, the specific surface area is 284 m^2/g, the pore volume 2.0 cm^3/g and the average pore diameter 20.5 nm, in the macropore range, the pore volume is 13.95 cm^3/g, the average pore diameter 0.732 μm and the porosity 91%.
出处
《过程工程学报》
CAS
CSCD
北大核心
2013年第2期351-355,共5页
The Chinese Journal of Process Engineering
关键词
纤维素
凝胶
无机盐
诱导
气凝胶
cellulose
gelation
organic salt
induction
aerogel
