摘要
通过混合不同类型的纳米纤维素制备混合气凝胶,分析其性能特征。将桉木纸浆经化学预处理,结合机械研磨法制备得到纤维素纳米纤丝(cellulose nanofibril,CNF),桉木微晶纤维素(MCC)经硫酸水解法制备得到纤维素纳米晶体(cellulose nanocrystal,CNC),通过透射电镜与X射线衍射仪观测发现二者具有不同的长径比和结晶度。利用悬浮滴定、叔丁醇置换、冷冻干燥等方法制备球形CNF气凝胶和CNF/CNC混合气凝胶,采用扫描电镜、傅里叶红外光谱仪、比表面积分析仪、万能力学试验机对气凝胶的微观形貌、化学官能团、比表面积、平均孔径及压缩性能进行表征,结果表明:CNF气凝胶内部呈现三维网络结构,片状与纤丝状交织,比表面积为91.07m^2/g,平均孔径为14.81 nm,受压缩到80%应变时,压缩强度为0.125 MPa;添加不同比例的CNC制备CNF/CNC混合气凝胶,当CNC添加量为25%时,气凝胶内部纤丝结构取代片状结构,孔隙更加均匀,比表面积升至143.09m^2/g,压缩强度增至0.2 MPa,化学官能团和晶型结构未发生明显变化。当CNC添加量过大(50%)时,则会造成各项性能的减弱。
As a promising green nanomaterial,nanocellulose is of increasing interest for a range of applications relevant to many different fields,such as,electronic components,material science and biomedical engineering due to its advantages of anisotropic shape,excellent mechanical properties,good biocompatibility,tailorable surface chemistry,and interesting optical properties.In this study,mixed aerogels were prepared by mixing different types of nanocellulose and their performance characteristics were examined.The cellulose nanofiber(CNF)was prepared by chemical pretreatment combined with mechanical grinding method,while the cellulose nanocrystal(CNC)was fabricated using the sulfuric acid hydrolysis.According to the examinations of the transmission electron microscopy and X-ray diffractometer,it showed that the prepared CNC and CNF had different length-diameter ratio and crystallinity.The spherical CNF aerogel and CNF/CNC mixed aerogel were prepared using the suspension titration,tert-butyl alcohol replacement,and freeze-dry methods.The morphology,chemical functional groups,specific surface area,average pore size and compressive properties of the aerogels were characterized by the scanning electron microscopy,Fourier transform infrared spectroscopy,surface area analyzer and universal mechanical testing machine.The results showed that the three-dimensional network structure of the CNF aerogel interlaced with flake and filament;the specific surface area was 91.07 m 2/g and the average pore size was 14.81 nm;the compressive strength was 0.125 MPa when it was compressed to 80%strain.The CNF/CNC mixed aerogel was prepared by adding different proportions of the CNC.Since the adding amount of the CNC was up to 25%,the internal fibrillar structure of aerogel replaced the lamellar structure,and the pores arranged more uniformly.The specific surface area was improved to 143.09 m 2/g while the compression strength increased to 0.2 MPa.Moreover,the chemical functional groups and structure did not change significantly.It was also found that,once the amount of the CNC was over 50%,the performance of the mixed aerogel would be worsening.
作者
张天蒙
张洋
江华
刘双
姚远
ZHANG Tianmeng;ZHANG Yang;JIANG Hua;LIU Shuang;YAO Yuan(College of Materials Science and Engineering,Nanjing Forestry University;College of Chemical Engineering,Nanjing Forestry University,Nanjing 210037,China)
出处
《林业工程学报》
北大核心
2018年第5期91-96,共6页
Journal of Forestry Engineering
基金
国家林业公益性行业科研专项(201504603)
