Fiber morphology with off-standing branches,as found in nature,e.g.,in goose downy feather,provides exquisite functions that can be barely achieved by man-made fiber systems.In this work,we develop a simple and scalab...Fiber morphology with off-standing branches,as found in nature,e.g.,in goose downy feather,provides exquisite functions that can be barely achieved by man-made fiber systems.In this work,we develop a simple and scalable method for generating downy feather-like para-aramid fibers and assemblies.Through treating commercial para-aramid microfibers with mild alkaline solution(low concentration of NaOH),a synergistic effect of chemical hydrolysis and physical shearing is successfully triggered to generate abundant nanofiber branches on the surface of para-aramid fibers.When compared with conventional monotonous structures,nonwovens composed of downy feather-like fibers exhibit a typical multiscale fiber morphology,larger specific surface area and smaller pore size,thus showing enhanced particles adsorption capacity(over twice of the pristine nonwoven),excellent oil absorption capacity(increased by~50%),improved air filtration performances(doubled the filtration efficiency)and effective thermal insulation(thermal conductivity=26.1 mW·m^(−1)·K^(−1)).More attractively,the intrinsic flame-retardant nature of para-aramid is well inherited by the downy feather-like fibers,and the fabrication process requires neither sophisticated equipment,nor tedious procedures,making us believe the strong competitiveness of these fibers and assemblies.展开更多
Heterocyclic aramid fibers,a typical kind of high-performance fibers,have been widely used in aerospace and protection fields because of their excellent mechanical properties.However,the application of heterocyclic ar...Heterocyclic aramid fibers,a typical kind of high-performance fibers,have been widely used in aerospace and protection fields because of their excellent mechanical properties.However,the application of heterocyclic aramid fibers as a reinforcement is hindered by the weak interfacial combination with matrix materials,especially epoxy.Traditional strategies enhancing the interfacial shear strength(IFSS)usually decrease the tensile strength.Therefore,simultaneous enhancement of both mechanical properties remains a challenge.Herein,we report a novel heterocyclic aramid fiber with high interfacial shear strength(49.3 MPa)and tensile strength(6.27 GPa),in which 4,4′-diamino-2′-chlorobenzanilide(DABA-Cl)and a small amount of graphene oxide(GO)are introduced through in-situ polymerization.Hydrogen bonds andπ–πinteraction between GO and polymer chains trigger the enhancement in crystallinity,orientation,and lateral interaction of the fibers,thus improving the tensile strength and interfacial shear strength of the fibers.Moreover,the interfacial interaction between fiber and epoxy is enhanced due to the improvement of the surface polarity of the fibers caused by DABA-Cl.Therefore,a method to improve both tensile strength and interfacial shear strength of heterocyclic aramid fibers was found by introducing GO and DABA-Cl,which may provide guidance for the design and preparation of other high-performance fibers.展开更多
基金supported by the Fundamental Research Funds for the Central Universities and Graduate Student Innovation Fund of Donghua University(No.CUSF-DH-D2020021).
文摘Fiber morphology with off-standing branches,as found in nature,e.g.,in goose downy feather,provides exquisite functions that can be barely achieved by man-made fiber systems.In this work,we develop a simple and scalable method for generating downy feather-like para-aramid fibers and assemblies.Through treating commercial para-aramid microfibers with mild alkaline solution(low concentration of NaOH),a synergistic effect of chemical hydrolysis and physical shearing is successfully triggered to generate abundant nanofiber branches on the surface of para-aramid fibers.When compared with conventional monotonous structures,nonwovens composed of downy feather-like fibers exhibit a typical multiscale fiber morphology,larger specific surface area and smaller pore size,thus showing enhanced particles adsorption capacity(over twice of the pristine nonwoven),excellent oil absorption capacity(increased by~50%),improved air filtration performances(doubled the filtration efficiency)and effective thermal insulation(thermal conductivity=26.1 mW·m^(−1)·K^(−1)).More attractively,the intrinsic flame-retardant nature of para-aramid is well inherited by the downy feather-like fibers,and the fabrication process requires neither sophisticated equipment,nor tedious procedures,making us believe the strong competitiveness of these fibers and assemblies.
基金the Ministry of Science and Technology of China(No.2016YFA0200100)the Beijing National Laboratory for Molecular Sciences(No.BNLMS-CXTD-202001)+1 种基金the National Natural Science Foundation of China(Nos.52102035,52021006,T2188101,51720105003,and 21790052)the Strategic Priority Research Program of CAS(No.XDB36030100).
文摘Heterocyclic aramid fibers,a typical kind of high-performance fibers,have been widely used in aerospace and protection fields because of their excellent mechanical properties.However,the application of heterocyclic aramid fibers as a reinforcement is hindered by the weak interfacial combination with matrix materials,especially epoxy.Traditional strategies enhancing the interfacial shear strength(IFSS)usually decrease the tensile strength.Therefore,simultaneous enhancement of both mechanical properties remains a challenge.Herein,we report a novel heterocyclic aramid fiber with high interfacial shear strength(49.3 MPa)and tensile strength(6.27 GPa),in which 4,4′-diamino-2′-chlorobenzanilide(DABA-Cl)and a small amount of graphene oxide(GO)are introduced through in-situ polymerization.Hydrogen bonds andπ–πinteraction between GO and polymer chains trigger the enhancement in crystallinity,orientation,and lateral interaction of the fibers,thus improving the tensile strength and interfacial shear strength of the fibers.Moreover,the interfacial interaction between fiber and epoxy is enhanced due to the improvement of the surface polarity of the fibers caused by DABA-Cl.Therefore,a method to improve both tensile strength and interfacial shear strength of heterocyclic aramid fibers was found by introducing GO and DABA-Cl,which may provide guidance for the design and preparation of other high-performance fibers.
