不同CNF添加量对CNC气凝胶结构与性能的影响
|
摘要
采用硫酸水解法制备纤维素纳米晶体(CNC),并通过悬浮滴定、叔丁醇置换和冷冻干燥制备球形纤维素气凝胶(CNCa)。为了提高CNCa的性能,将化学预处理结合机械研磨法制备得到的纤维素纳米纤丝(CNF),添加到CNC悬浮液中,最后制得CNC/CNF混合气凝胶。采用透射电镜、X-射线衍射仪观察纤维素的形态和结晶度,利用扫描电镜、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、化学态、比表面积及压缩性能进行表征。结果表明:CNC与CNF的尺寸、形态和结晶度均有差异;CNCa内部纤丝无序交联,比表面积达96.67 m2/g;在80%应变下,压缩强度为0.148 MPa。添加CNF,气凝胶直径随之增加,形态由"球形"趋向"米粒状";当CNF添加量为25%时,内部孔隙丰富,比表面积增至134.41 m2/g,压缩强度增至0.221 MPa。CNF的添加未对CNC气凝胶的化学官能团和晶型结构产生影响;但CNF添加量过大时,气凝胶各项性能均减弱。
Cellulose nanocrystals( CNC) were prepared by sulfuric acid hydrolysis and spherical cellulose aerogels( CNCa)were prepared by suspension titration,tert-butanol displacement and freeze-drying. In order to improve the performance of CNCa,the chemical pretreatment was combined with the mechanical grinding method to prepare the cellulose nanofibril(CNF),which was added to the CNC solution,and finally the CNC/CNF mixed aerogel was made. Transmission electron microscopy and X-ray diffraction were used to observe the morphology and crystallinity of cellulose. The microstructure,chemical state,specific surface area and compression properties of aerogel were characterized by scanning electron microscope,Fourier infrared spectrometer,specific surface area analyzer and universal mechanical testing machine. The size,shape and crystallinity of CNC and CNF were different. CNCa internal filodex crosslinking,with a specific surface area of96.67 m~2/g,with a compression strength of 0.148 MPa under 80% strain. With the addition of CNF,the diameter of the aerogels increased with the morphology from"spherical"to"rice-like",when CNF was added to 25%,the internal porosity was rich,and the specific surface area increased to 134.41 m~2/g,and the compression strength increased to 0.221 MPa.The addition of CNF did not affect the chemical functional groups and crystal structure of the CNC aerogel. However,the performance of aerogel was reduced when the CNF was too large.
Cellulose nanocrystals( CNC) were prepared by sulfuric acid hydrolysis and spherical cellulose aerogels( CNCa)were prepared by suspension titration,tert-butanol displacement and freeze-drying. In order to improve the performance of CNCa,the chemical pretreatment was combined with the mechanical grinding method to prepare the cellulose nanofibril(CNF),which was added to the CNC solution,and finally the CNC/CNF mixed aerogel was made. Transmission electron microscopy and X-ray diffraction were used to observe the morphology and crystallinity of cellulose. The microstructure,chemical state,specific surface area and compression properties of aerogel were characterized by scanning electron microscope,Fourier infrared spectrometer,specific surface area analyzer and universal mechanical testing machine. The size,shape and crystallinity of CNC and CNF were different. CNCa internal filodex crosslinking,with a specific surface area of96.67 m~2/g,with a compression strength of 0.148 MPa under 80% strain. With the addition of CNF,the diameter of the aerogels increased with the morphology from"spherical"to"rice-like",when CNF was added to 25%,the internal porosity was rich,and the specific surface area increased to 134.41 m~2/g,and the compression strength increased to 0.221 MPa.The addition of CNF did not affect the chemical functional groups and crystal structure of the CNC aerogel. However,the performance of aerogel was reduced when the CNF was too large.
引文
[1]KISTLER S S.Coherent expanded aerogels and jellies[J].Nature,1931,127:741-741.
[2]张伟娜.疏水性二氧化硅气凝胶的常压制备及其性能表征[D].长春:长春理工大学,2006.
[3]KLOSER E,DEREK G.Surface grafting of cellulose nanocrystals with poly(ethylene oxide)in aqueous media[J].Aqueous Media,2010,26(16):13450-13456.
[4]张俐娜.天然高分子改性材料及应用[M].北京:化学工业出版社,2006.
[5]ZHANG Z,SBE G,RENTSCH D,et al.Ultralightweight and flexible silylated nanocellulose sponges for the selective removal of oil from water[J].Geographical Research,2009,26(8):2659-2668.
[6]李淑君.植物纤维水解技术[M].北京:化学工业出版社,2009.
[7]KLEMM D,KRAMER F,MORITZ S,et al.Nanocelluloses:a new family of nature-based materials[J].Angewandte Chemie,2011,50(24):5438-5466.
[8]JIN H,NISHIYAMA Y,WADA M,et al.Nanofibrillar cellulose aerogels[J].Colloids&Surfaces A Physicochemical&Engineering Aspects,2004,240(1/2/3):63-67.
[9]赵华,张洋,王晓宇,等.液氮冷冻干燥法制备纳米纤维素气凝胶[J].林业工程学报,2017,2(4):109-114.
[10]SHAMSKAR K R,HEIDARI H,RASHIDI A.Preparation and evaluation of nanocrystalline cellulose aerogels from raw cotton and cotton stalk[J].Industrial Crops&Products,2016,93:203-211.
[11]JIAO Y,WAN C,QIANG T,et al.Synthesis of superhydrophobic ultralight aerogels from nanofibrillated cellulose isolated from natural reed for high-performance adsorbents[J].Applied Physics A,2016,122(7):686.
[12]SEHAQUI H,ZHOU Q,BERGLUND L A.High-porosity aerogels of high specific surface area prepared from nanofibrillated cellulose(NFC)[J].Composites Science&Technology,2011,71(13):1593-1599.
[13]姚远,张洋,赵华,等.酸法制备纳米纤维素特性及其气凝胶的制备[J].纤维素科学与技术,2017,25(2):38-44.
[14]李坚.木材波普学[M].北京:科学出版社,2002.
[15]GILBERTO S,JULIEN B,ALAIN D.Cellulose whiskers versus microfibrils:influence of the nature of the nanoparticle and its surface functionalization on the thermal and mechanical properties of nanocomposites[J].Biomacromolecules,2009,10(2):425-432.
[16]ROMAN M,WINTER W T.Effect of sulfate groups from sulfuric acid hydrolysis on the thermal degradation behavior of bacterial cellulose[J].Biomacromolecules,2004,5(5):1671-1677.
[17]CHIEN H C,CHENG W Y,WANG Y H,et al.Ultrahigh specific capacitances for supercapacitors achieved by nickel cobaltite/carbon aerogel composites[J].Advanced Functional Materials,2012,22(23):5038-5043.
[18]JIAN L,YUN L,YANG D,et al.Lignocellulose aerogel from wood-Ionic liquid solution(1-Allyl-3-methylimidazolium Chloride)under freezing and thawing conditions[J].Biomacromolecules,2011,12(5):1860.
[19]LU P,HSIEH Y L.Preparation and characterization of cellulose nanocrystals from rice straw[J].Carbohydrate Polymers,2012,87(1):564-573.
[20]PKKM,VAPAAVUORI J,SILVENNOINEN R,et al.Long and entangled native cellulose I nanofibers allow flexible aerogels and hierarchically porous templates for functionalities[J].Soft Matter,2008,4(12):2492-2499.
[2]张伟娜.疏水性二氧化硅气凝胶的常压制备及其性能表征[D].长春:长春理工大学,2006.
[3]KLOSER E,DEREK G.Surface grafting of cellulose nanocrystals with poly(ethylene oxide)in aqueous media[J].Aqueous Media,2010,26(16):13450-13456.
[4]张俐娜.天然高分子改性材料及应用[M].北京:化学工业出版社,2006.
[5]ZHANG Z,SBE G,RENTSCH D,et al.Ultralightweight and flexible silylated nanocellulose sponges for the selective removal of oil from water[J].Geographical Research,2009,26(8):2659-2668.
[6]李淑君.植物纤维水解技术[M].北京:化学工业出版社,2009.
[7]KLEMM D,KRAMER F,MORITZ S,et al.Nanocelluloses:a new family of nature-based materials[J].Angewandte Chemie,2011,50(24):5438-5466.
[8]JIN H,NISHIYAMA Y,WADA M,et al.Nanofibrillar cellulose aerogels[J].Colloids&Surfaces A Physicochemical&Engineering Aspects,2004,240(1/2/3):63-67.
[9]赵华,张洋,王晓宇,等.液氮冷冻干燥法制备纳米纤维素气凝胶[J].林业工程学报,2017,2(4):109-114.
[10]SHAMSKAR K R,HEIDARI H,RASHIDI A.Preparation and evaluation of nanocrystalline cellulose aerogels from raw cotton and cotton stalk[J].Industrial Crops&Products,2016,93:203-211.
[11]JIAO Y,WAN C,QIANG T,et al.Synthesis of superhydrophobic ultralight aerogels from nanofibrillated cellulose isolated from natural reed for high-performance adsorbents[J].Applied Physics A,2016,122(7):686.
[12]SEHAQUI H,ZHOU Q,BERGLUND L A.High-porosity aerogels of high specific surface area prepared from nanofibrillated cellulose(NFC)[J].Composites Science&Technology,2011,71(13):1593-1599.
[13]姚远,张洋,赵华,等.酸法制备纳米纤维素特性及其气凝胶的制备[J].纤维素科学与技术,2017,25(2):38-44.
[14]李坚.木材波普学[M].北京:科学出版社,2002.
[15]GILBERTO S,JULIEN B,ALAIN D.Cellulose whiskers versus microfibrils:influence of the nature of the nanoparticle and its surface functionalization on the thermal and mechanical properties of nanocomposites[J].Biomacromolecules,2009,10(2):425-432.
[16]ROMAN M,WINTER W T.Effect of sulfate groups from sulfuric acid hydrolysis on the thermal degradation behavior of bacterial cellulose[J].Biomacromolecules,2004,5(5):1671-1677.
[17]CHIEN H C,CHENG W Y,WANG Y H,et al.Ultrahigh specific capacitances for supercapacitors achieved by nickel cobaltite/carbon aerogel composites[J].Advanced Functional Materials,2012,22(23):5038-5043.
[18]JIAN L,YUN L,YANG D,et al.Lignocellulose aerogel from wood-Ionic liquid solution(1-Allyl-3-methylimidazolium Chloride)under freezing and thawing conditions[J].Biomacromolecules,2011,12(5):1860.
[19]LU P,HSIEH Y L.Preparation and characterization of cellulose nanocrystals from rice straw[J].Carbohydrate Polymers,2012,87(1):564-573.
[20]PKKM,VAPAAVUORI J,SILVENNOINEN R,et al.Long and entangled native cellulose I nanofibers allow flexible aerogels and hierarchically porous templates for functionalities[J].Soft Matter,2008,4(12):2492-2499.
© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |