纳米纤维素聚乙烯醇复合凝胶的制备及表征

摘要

为了增强聚乙烯醇(PVA)凝胶,采用2,2,6,6四甲基哌啶氧自由基(TEMPO)氧化法制得直径4~10 nm、长径比达到100以上的纤维素纳米纤维(CNF),将CNF与PVA在水相中进行混合,并进一步添加硼砂、戊二醛交联制备增强型CNF PVA复合凝胶材料.考察在不同交联剂的条件下CNF与PVA的质量分数对CNF PVA复合凝胶黏弹性及其内部孔隙结构的影响.结果表明:硼砂交联的CNF PVA复合凝胶的黏弹性随PVA质量分数的增加而增大,而其刚性随CNF含量的增大而提高,随CNF的增加CNF PVA复合凝胶内部孔隙结构更为丰富,形成蜂窝状的多孔材料;戊二醛交联的CNF PVA复合凝胶的黏弹性随PVA及CNF质量分数的增加而增大.因此,CNF的复合添加及交联能够有效改善PVA凝胶的力学性能及孔隙结构,达到增强效果.%The cellulose nanofibers ( CNF) with diameters of 4-10 nm,and the length-diameter ratio more than 100,was prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl ( TEMPO) oxidation. Polyvinyl alcohol ( PVA) was mixed with the obtained CNF to prepare enhanced CNF-PVA composite gels cross-linked by borax and glutaraldehyde respectively.The effects of CNF and PVA content on the property of CNF-PVA composite gel were studied.Results showed that the viscoelasticity of CNF-PVA composite hydrogels cross-linked by borax increased with the increase of PVA content.The rigidity of CNF-PVA composite hydrogels increased with the CNF content.With the addition of CNF,CNF-PVA composite gels had more abundant honeycomb pore structures. The viscoelasticity of CNF-PVA composite hydrogels cross-linked by glutaraldehyde was improved with more addition of CNF. Therefore,the addition of CNF and its effective cross-linking improved the mechanical properties and porous structures of PVA gels,and the enhanced CNF-PVA composite gels were prepared.