Production of porous cellulose aerogel fibers by an extrusion process
Production of porous cellulose aerogel fibers by an extrusion process
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DOI：
10.1016/j.supflu.2015.06.011
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发表时间：
2015-11-01
影响因子：
3.9
通讯作者：
Ratke, Lorenz
中科院分区：
文献类型：
--
作者：
Karadagli, Ilknur;Schulz, Bjoern;Ratke, Lorenz
将薄挤出纤维形式的轻质多孔纤维素气凝胶的制备、生产和性质与单片进行比较。纤维素气凝胶是由微晶纤维素在水合硫氰酸钙盐熔体中合成的，其在冷却时在约80摄氏度下形成凝胶。系统地进行了双螺杆挤出实验，得到细的和湿的纤维素长丝。在乙醇中洗涤和凝结湿凝胶，然后用CO2超临界干燥，得到纤维素气凝胶长丝。这些方面的特点是信封密度，氮吸附-脱附（BET）分析，导热系数测量，拉伸和压缩测试和扫描电子显微镜（SEM）。微结构可以被描述为具有10至100 nm的孔径和约10至25 nm的原纤维直径的纳米原纤维的开放多孔网络。超临界干燥（SCD）纤维素气凝胶的密度在0.009-0.137 g/cm（3）的范围内，BET比表面积（SSABET）在120 - 230 m2/g之间。纤维素气凝胶具有从0.04到0.075 W/m.K的热导率和压缩模量高达16.2 MPa。随着纺丝原液中纤维素含量的增加，气凝胶长丝的拉伸强度增加。挤出的纤维素气凝胶长丝显示出它们的比表面积对挤出温度的依赖性：纺丝温度越高，表面积越高。(C)2015 Elsevier B. V.版权所有。
The preparation, production and properties of light weight, porous cellulose aerogels in the form of thin extruded fibers is compared to monolithic pieces. The cellulose aerogels were synthesized from microcrystalline cellulose in a hydrated calciumthiocyanate salt melt, which upon cooling forms a gel at around 80 degrees C. Twin screw extrusion experiments were performed systematically yielding thin and wet cellulose filaments. Washing and coagulation of the wet gels in ethanol was followed by supercritical drying with CO2 yielding cellulose aerogel filaments. These were characterized with regard to envelope density, nitrogen adsorption-desorption (BET) analysis, thermal conductivity measurements, tensile and compression tests and scanning electron microscopy (SEM). The microstructure can be described as an open porous network of nano-fibrils with pore sizes ranging from 10 to 100 nm and fibril diameters of around 10 to 25 nm. The densities of supercritically dried (SCD) cellulose aerogels were in the range of 0.009-0.137 g/cm(3) and the BET specific surface areas (SSABET) were between 120 and 230 m(2)/g. The cellulose aerogel possessed thermal conductivities from 0.04 to 0.075 W/m.K and compressive moduli up to 16.2 MPa. The tensile strength of aerogel filaments increases with the increasing cellulose amount in the spin dope. Extruded cellulose aerogel filaments show a dependency of their specific surface area on the extrusion temperature: the higher the spinning temperature the higher the surface area. (C) 2015 Elsevier B.V. All rights reserved.