Lightweight,highly strong and bio-based structural materials remain a long-lasting challenge.Here,inspired by nacre,a lightweight and high mechanical performance cellulosic material was fabricated via a facile and eff...Lightweight,highly strong and bio-based structural materials remain a long-lasting challenge.Here,inspired by nacre,a lightweight and high mechanical performance cellulosic material was fabricated via a facile and effective top-down approach and the resulting material has a high tensile strength of149.21 MPa and toughness of 1.91 MJ/m^(3).More specifically,the natural balsawood(NW) was subjected to a simple chemical treatment,removing most lignin and partial hemicellulose,follow by freeze-drying,forming wood aerogel(WA).The delignification process produced many pores and exposed numerous aligned cellulose nanofibers.Afterwards,the WA absorbed a quantity of moisture and was directly densified to form above high-performance cellulosic material.Such treatment imitates highly ordered"brick-and-mortar" arrangement of nacre,in which water molecules plays the role of mortar and cellulose nanofibrils make the brick part.The lightweight and good mechanical properties make this material promising for new energy car,aerospace,etc.This paper also explains the strengthening mechanism for making biomimetic materials by water molecules-induced hydrogen bonding and will open a new path for designing high-performance bio-based structural materials.展开更多
Researches on novel natural fibers in polymer-based composites will help promote the invention of novel reinforcement and expand their possible applications.Herein,in this study,novel cellulosic fibers were extracted ...Researches on novel natural fibers in polymer-based composites will help promote the invention of novel reinforcement and expand their possible applications.Herein,in this study,novel cellulosic fibers were extracted from the stem of manau rattan(Calamus manan)by mechanical separation.The chemical,thermal,mechanical and morphological properties of manau rattan fibers were comprehensively analyzed and studied by Fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD)analysis,thermogravimetric analysis(TGA),single fiber tensile test and scanning electron microscopy(SEM).Component analysis re-sults showed that the cellulose,hemicellulose and lignin contents of C.manan fibers were 42wt%,20wt%,and 27wt%,respectively.The surface of the rattan fiber was hydrophilic according to the oxygen/carbon ratio of 0.49.The C.manan has a crystalline index of 48.28%,inducing a max-imum degradation temperature of 332.8°C.This reveals that it can be used as a reinforcement for thermoplastic composites whose operating temperature is below 300°C.The average ten-sile strength can reach(273.28±52.88)MPa,which is beneficial to improve the mechanical properties of rattan fiber reinforced composites.The SEM images displayed the rough surface of the fiber,which helped to enhance the interfacial adhesion between the fibers and matrices in composites.These results indicate the great potential of C.manan fibers as the reinforcement in polymer-based composites.展开更多
Natural wood(NW)was treated with sodium chlorite to obtain delignified wood(DW)in this study,then epoxy was impregnated to get transparent wood(TW),and finally the TW was coated with perfluorodecyltriethoxysilane(FAS)...Natural wood(NW)was treated with sodium chlorite to obtain delignified wood(DW)in this study,then epoxy was impregnated to get transparent wood(TW),and finally the TW was coated with perfluorodecyltriethoxysilane(FAS)to acquire hydrophobic and transparent wood(HTW).The hydroxyl group generated by the hydrolysis of the FAS and the hydroxyl group of the epoxy underwent a dehydration condensation reaction to generate a Si-O-C bond,while the FAS molecules were also dehydrated and condensed to form a Si-O-Si bond according to Fourier transform infrared(FT-IR)spectroscopy and X-ray photoelectron spectroscopy(XPS).Therefore,the mechanical property and thermal stability of the HTW were better than the TW based on their tensile tests and thermogravimetric analysis(TGA).Due to the large reduction of hydroxyl in epoxy,the hydrophobicity of the HTW was greatly improved compared with the TW,and their contact angles were 113°and 77°,respectively.The results of scanning electron microscopy(SEM)showed that epoxy was filled in the voids of wood.In addition,the coating of the FAS did not obviously reduce the transmittance,and the transmittance of the TW and HTW was 69%and 67%at 750 nm.All in all,the HTW has potential for application in transparent decoration.展开更多
基金supported by the National Natural Science Foundation of China (No.51803093)National Science Foundation of Jiangsu Province (No.BK20180770)。
文摘Lightweight,highly strong and bio-based structural materials remain a long-lasting challenge.Here,inspired by nacre,a lightweight and high mechanical performance cellulosic material was fabricated via a facile and effective top-down approach and the resulting material has a high tensile strength of149.21 MPa and toughness of 1.91 MJ/m^(3).More specifically,the natural balsawood(NW) was subjected to a simple chemical treatment,removing most lignin and partial hemicellulose,follow by freeze-drying,forming wood aerogel(WA).The delignification process produced many pores and exposed numerous aligned cellulose nanofibers.Afterwards,the WA absorbed a quantity of moisture and was directly densified to form above high-performance cellulosic material.Such treatment imitates highly ordered"brick-and-mortar" arrangement of nacre,in which water molecules plays the role of mortar and cellulose nanofibrils make the brick part.The lightweight and good mechanical properties make this material promising for new energy car,aerospace,etc.This paper also explains the strengthening mechanism for making biomimetic materials by water molecules-induced hydrogen bonding and will open a new path for designing high-performance bio-based structural materials.
基金support by National Natural Science Foundation of China(No.51803093)Natural Science Foundation of Jiangsu Province(No.BK20180770).
文摘Researches on novel natural fibers in polymer-based composites will help promote the invention of novel reinforcement and expand their possible applications.Herein,in this study,novel cellulosic fibers were extracted from the stem of manau rattan(Calamus manan)by mechanical separation.The chemical,thermal,mechanical and morphological properties of manau rattan fibers were comprehensively analyzed and studied by Fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD)analysis,thermogravimetric analysis(TGA),single fiber tensile test and scanning electron microscopy(SEM).Component analysis re-sults showed that the cellulose,hemicellulose and lignin contents of C.manan fibers were 42wt%,20wt%,and 27wt%,respectively.The surface of the rattan fiber was hydrophilic according to the oxygen/carbon ratio of 0.49.The C.manan has a crystalline index of 48.28%,inducing a max-imum degradation temperature of 332.8°C.This reveals that it can be used as a reinforcement for thermoplastic composites whose operating temperature is below 300°C.The average ten-sile strength can reach(273.28±52.88)MPa,which is beneficial to improve the mechanical properties of rattan fiber reinforced composites.The SEM images displayed the rough surface of the fiber,which helped to enhance the interfacial adhesion between the fibers and matrices in composites.These results indicate the great potential of C.manan fibers as the reinforcement in polymer-based composites.
基金support by National Natural Science Foundation of China(No.51803093)Natural Science Foundation of Jiangsu Provinc e(No.BK20180770).
文摘Natural wood(NW)was treated with sodium chlorite to obtain delignified wood(DW)in this study,then epoxy was impregnated to get transparent wood(TW),and finally the TW was coated with perfluorodecyltriethoxysilane(FAS)to acquire hydrophobic and transparent wood(HTW).The hydroxyl group generated by the hydrolysis of the FAS and the hydroxyl group of the epoxy underwent a dehydration condensation reaction to generate a Si-O-C bond,while the FAS molecules were also dehydrated and condensed to form a Si-O-Si bond according to Fourier transform infrared(FT-IR)spectroscopy and X-ray photoelectron spectroscopy(XPS).Therefore,the mechanical property and thermal stability of the HTW were better than the TW based on their tensile tests and thermogravimetric analysis(TGA).Due to the large reduction of hydroxyl in epoxy,the hydrophobicity of the HTW was greatly improved compared with the TW,and their contact angles were 113°and 77°,respectively.The results of scanning electron microscopy(SEM)showed that epoxy was filled in the voids of wood.In addition,the coating of the FAS did not obviously reduce the transmittance,and the transmittance of the TW and HTW was 69%and 67%at 750 nm.All in all,the HTW has potential for application in transparent decoration.
