叔丁醇冷冻干燥法制备纳米纤维素气凝胶

发布时间：2018-03-24 20:59

本文选题：纳米纤维素　切入点：气凝胶　出处：《林业工程学报》2017年01期

【摘要】：以纳米纤维素为原料,采用"CaCl_2溶液促进物理凝胶法"制备水凝胶,选用叔丁醇溶液为置换溶剂并采用"多步法"完成溶剂置换,最后通过冷冻干燥法制备纳米纤维素气凝胶。通过扫描电子显微镜(SEM)、全自动比表面积与孔隙度分析仪和热重分析仪(TG)对所制备的纳米纤维素气凝胶进行微观形貌、比表面积、孔径分布及热稳定性进行表征分析。结果表明:叔丁醇冷冻干燥法制备的纳米纤维素气凝胶是具有层状的以中孔和大孔为主的多孔材料,其比表面积可达174.3 m2/g,收缩率仅为7.86%,平均孔径约为18.4 nm。随着纤维素质量分数的增加,纳米纤维素气凝胶的吸附量和比表面积增大,孔隙度增加,收缩率逐渐减小;纳米纤维素气凝胶具有与微晶纤维素和纳米纤维素相似的热稳定特性。CaCl_2溶液通过改变原始溶胶体系的电荷分布而使粒子更易相互靠近聚集形成凝胶,落入其中的纳米纤维素颗粒会保持其落入瞬间的完整状态。
[Abstract]:Using nano-cellulose as raw material, hydrogel was prepared by "CaCl_2 solution promoting physical gel method". Tert-butanol solution was used as replacement solvent and solvent replacement was completed by "multi-step method". Finally, nanocellulose aerogels were prepared by freeze-drying method. The nano-cellulose aerogels were prepared by scanning electron microscope (SEM), automatic surface area and porosity analyzer and thermogravimetric analyzer (TGG). The pore size distribution and thermal stability were analyzed. The results showed that the nano-cellulose aerogels prepared by freeze drying with tert-butanol were mesoporous and macroporous porous materials. The specific surface area is 174.3 m2 / g, the shrinkage is only 7.86 and the average pore size is about 18.4 nm. With the increase of cellulose mass fraction, the adsorption capacity and specific surface area of nano-cellulose aerogels increase, the porosity increases and the shrinkage decreases gradually. Nanocellulose aerogels have thermal stability similar to those of microcrystalline cellulose and nanocellulose. CaCl2 solution can easily aggregate particles closer to each other to form a gel by changing the charge distribution of the original sol system. The nanocellulose particles that fall into it will remain intact for a moment.
【作者单位】：南京林业大学材料科学与工程学院;南京林业大学化学工程学院;
【基金】：国家林业公益性行业科研专项(201504603) 南京林业大学优秀博士学位论文创新基金项目基金(163020772)
【分类号】：TQ352.79

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