纳米纤维素增强SiO2气凝胶力学性能与微观结构
Mechanical properties and microstructure of SiO2 aerogel reinforced with cellulose nanofibrils

为克服SiO2气凝胶强度低、易破碎等缺点，通过原位溶胶-凝胶法制备纳米纤维素（CNF）增强SiO2气凝胶，并对SiO2气凝胶的化学结构、微观形貌和力学、物理性能进行表征分析，探讨了CNF对SiO2气凝胶力学性能的增强机制。结果表明：CNF独特的纳米级网络结构可增强SiO2颗粒之间的联结强度；Si—OH（960 cm-1）和Si—O—Si（1 225 cm-1、1 056 cm-1和800 cm-1）等特征吸收峰的出现表明，CNF与SiO2之间形成稳定的化学键联结；采用不同含量CNF气凝胶作为SiO2增强相均可达到增强力学性能的效果，同时仍能保持SiO2气凝胶本身质轻、高孔隙率、高比表面积等特性；当以CNF质量分数为6wt%的溶液制备气凝胶时，CNF增强SiO2气凝胶具有最优的力学性能，压缩模量和压缩强度分别为12.43 MPa和2.59 MPa。 In order to eliminate the low mechanical property and brittle character of SiO2 aerogel, the cellulose nanofibrils (CNF) were used to reinforce SiO2 aerogel through in-situ sol-gel process.The chemical structure, morphology, mechanical and physical properties of SiO2 aerogels were characterized and analyzed.The improvement of mechanical properties and mechanism of SiO2 aerogel reinforced with CNF were investigated. The results show that the CNF of unique nano network structure can enhance the bonding strength between SiO2 particles. The appearance of Si-OH (960 cm-1) and Si-O-Si (1 225 cm-1, 1 056 cm-1 and 800 cm-1) characteristic absorption peaks represent the formation of stable chemical bond between cellulose and SiO2. The all CNF of different content can significantly improve the mechanical properties of SiO2 aerogel, and still remain SiO2 aerogel itself light mass, high porosity and high specific area. When the CNF mass fraction is 6wt%, the SiO2 aerogel reinforced with CNF has the best mechanical properties; its compressive modulus and strength are 12.43 MPa and 2.59 MPa, respectively. 林业公益化行业科研专项（201504603）；中国农科院农业科技创新工程项目“生物质转化利用装备创新团队”通信作者：王思群，教授，研究方向为木质复合材料、生物质纳米材料、功能化纳米材料E-mail：swang@utk.edu.何春霞，教授，研究方向为生物质增强高分子复合材料E-mail：chunxiahe@tom.com