Flame retardants play a crucial role in improving theflame retardant properties of polymer materials.In recent years,environmental problems caused byflame retar-dants have attracted widespread attention.It is urgent to ...Flame retardants play a crucial role in improving theflame retardant properties of polymer materials.In recent years,environmental problems caused byflame retar-dants have attracted widespread attention.It is urgent to use green and effective methods to prepareflame retardant polymers.Bioinspired nanocomposites with lay-ered structures seem to provide effective ideas,but in general,their hydrophilic raw materials limit their applications in certainfields.Here,we prepared biomimetic composites with a layered“brick-and-mortar”structure by gravity-induced depo-sition using polyimide as the polymer matrix and montmorillonite(MMT)as thefiller.The well-arranged structures of the composite material could isolate oxygen and prevent combustible gases from escaping.The gas barrier performance has been greatly improved,in which the water vapor transmission rate and the oxygen trans-mission rate decreased by 99.18%and three orders of magnitude,respectively.Theflame retardant performance has also been improved,and its limiting oxygen index can reach 67.9%.The polyimide matrix can be converted to water-insoluble by ther-mal imidization of water-soluble poly(amic acid)salt precursors,which endows the composites with low hygroscopicity.The coating containing MMT can protect against polyurethane(PU)foam fromfire.During the conical calorimetric test,the coated sample self-extinguished,and the peak heat release rate,total heat release,and total smoke production are significantly decreased by 53.39%,40.69%,and 53.03%,respectively.Taking advantage of these properties,this work utilizes a facile method to prepare biomimetic composites with low moisture absorption,excellent gas barrier properties,andflame retardancy,which have great application potential.展开更多
Relatively well crystallized and high aspect ratio Mg-Al layered double hydroxides(LDHs) were prepared by coprecipitation process in aqueous solution and further rehydrated to an organic modified LDH(OLDH) in the ...Relatively well crystallized and high aspect ratio Mg-Al layered double hydroxides(LDHs) were prepared by coprecipitation process in aqueous solution and further rehydrated to an organic modified LDH(OLDH) in the presence of surfactant. The intercalated structure and high aspect ratio of OLDH were verified by X-ray diffraction(XRD) and scanning electron microscopy(SEM). A series of poly(propylene carbonate)(PPC)/OLDH composite films with different contents of OLDH were prepared via a melt-blending method. Their cross section morphologies, gas barrier properties and tensile strength were investigated as a function of OLDH contents. SEM results show that OLDH platelets are well dispersed within the composites and oriented parallel to the composite sheet plane. The gas barrier properties and tensile strength are obviously enhanced upon the incorporation of OLDH. Particularly, PPC/2%OLDH film exhibits the best barrier properties among all the composite films. Compared with pure PPC, the oxygen permeability coefficient(OP) and water vapor permeability coefficient(WVP) is reduced by 54% and 17% respectively with 2% OLDH addition. Furthermore, the tensile strength of PPC/2%OLDH is 83% higher than that of pure PPC with only small lose of elongation at break. Therefore, PPC/OLDH composite films show great potential application in packaging materials due to its biodegradable properties, superior oxygen and moisture barrier characteristics.展开更多
In this study,polypyrrole-silver coated layered double hydroxides(LDHs@PPy-Ag)was prepared by chemical polymerization of pyrrole(Py)with silver ions.Silver nanoparticles(AgNPs)could be uniformly reduced onto PPy coati...In this study,polypyrrole-silver coated layered double hydroxides(LDHs@PPy-Ag)was prepared by chemical polymerization of pyrrole(Py)with silver ions.Silver nanoparticles(AgNPs)could be uniformly reduced onto PPy coatings in situ by redox reaction during simultaneous polymerization process.And LDHs@PPy-Ag/poly(ε-caprolactone)(PCL)nanocomposites were fabricated by solution casting method.It is revealed that spherical AgNPs are loaded on PPy coatings uniformly.Particularly,compared with pure PCL,LDHs@PPy-Ag/PCL nanocomposites with incorporation of only 1 wt%LDHs@PPy-Ag show a 17%increase in tensile strength(36.5 MPa)and a 29%increase in elongation at break(822%).Upon PPy-Ag coatings onto original LDHs,oxygen relative permeability of LDHs@PPy-Ag/PCL nanocomposites decreases to 52%with the same addition.Meanwhile,due to the double antibacterial activity of PPy and AgNPs,the antibacterial rate of LDHs@PPy-Ag reaches 100%.And the corresponding LDHs@PPy-Ag/PCL nanocomposites also show outstanding antibacterial activity.Considering the superiority of their comprehensive performance,antibacterial LDHs@PPy-Ag/PCL nanocomposites can be used further for the application as biodegradable polymeric active packaging materials.展开更多
It is a daunting task to develop a promising strategy at an industrial scale for simultaneously ameliorating ductility and gas barrier performance of poly(lactic acid)(PLA)films in the application of green packaging.I...It is a daunting task to develop a promising strategy at an industrial scale for simultaneously ameliorating ductility and gas barrier performance of poly(lactic acid)(PLA)films in the application of green packaging.In this work,biaxial stretching and constrained annealing were employed to prepare transparent PLA films with superior ductility and barrier properties.The oriented nano-sized crystals induced by biaxial stretching were developed into regularαform during constrained annealing,which could not only serve as“nano-barrier wall”to impede the diffusion and dissolution of gas molecules,but also strengthen amorphous chain entanglement network as physical crosslink to enhance ductility.As a result,the as-prepared PLA films exhibited an outstanding comprehensive performance with a low oxygen and water vapor permeability coefficient of 0.733×10^(-14) cm^(3)·cm·cm^(-2)·s^(-1)·Pa^(-1) and 3.82×10^(-14) g·cm·cm^(-2)·s^(-1)·Pa^(-1),respectively,outstanding ductility with elongation at break of 66.0%,high yield strength of 84.2 MPa,and good transparency of more than 80%at 550 nm.The new insight in the relationship between microscopic amorphous and crystalline structure and macroscopic performance is conducive to alleviating the intrinsic defects of brittle and insufficient barrier PLA films without the aid of any heterogenous modifiers,facilitating their widespread commercialization in the booming sustainable packaging market.展开更多
Poly(propylene carbonate) (PPC), the copolymerization product of carbon dioxide and propylene oxide, was chlorinated for the first time in our laboratory. Nuclear magnetic resonance (NMR) spectroscopy and ion ch...Poly(propylene carbonate) (PPC), the copolymerization product of carbon dioxide and propylene oxide, was chlorinated for the first time in our laboratory. Nuclear magnetic resonance (NMR) spectroscopy and ion chromatography test showed that chlorine atoms were successfully introduced onto the polymer chains of PPC. We named this newborn polymer material as chlorinated poly(propylene carbonate) (CPPC). It is worth noting that the reaction conditions of the chlorination of PPC were quite mild, which could be easily and simply realized at industrial level. What is more important is that CPPC possessed many more distinguished properties in solubility, wettability, adhesiveness, and gas barrier compared with PPC. For example, the bonding strength of CPPC as thermal adhesive is nearly four times higher than that of PPC for wood, stainless steel and glass. The oxygen permeability coefficient of CPPC exhibits a decrease of 33% compared with that of PPC. Moreover, CPPC is quite stable in air, whereas it could be well biodegraded in soil compared with PPC. These results indicated that CPPC could be widely used in the fields of coating, adhesive, barrier materials and so on, which could greatly promote the development of PPC industry.展开更多
基金Ministry of Science and Technology,Grant/Award Number:2022YFB3806601National Natural Science Foundation of China,Grant/Award Numbers:U20A20255,51873239,52103022,52203286+2 种基金Guangdong Provincial Department of Science and Technology,Grant/Award Numbers:2020B010182001,2020B010179001,2021A1515010664,2019B040401002Fellowship of China Postdoctoral Science Foundation,Grant/Award Number:2022M723572Guangxi Provincial Department of Science and Technology,Grant/Award Number:GLESI-KFKY2301013。
文摘Flame retardants play a crucial role in improving theflame retardant properties of polymer materials.In recent years,environmental problems caused byflame retar-dants have attracted widespread attention.It is urgent to use green and effective methods to prepareflame retardant polymers.Bioinspired nanocomposites with lay-ered structures seem to provide effective ideas,but in general,their hydrophilic raw materials limit their applications in certainfields.Here,we prepared biomimetic composites with a layered“brick-and-mortar”structure by gravity-induced depo-sition using polyimide as the polymer matrix and montmorillonite(MMT)as thefiller.The well-arranged structures of the composite material could isolate oxygen and prevent combustible gases from escaping.The gas barrier performance has been greatly improved,in which the water vapor transmission rate and the oxygen trans-mission rate decreased by 99.18%and three orders of magnitude,respectively.Theflame retardant performance has also been improved,and its limiting oxygen index can reach 67.9%.The polyimide matrix can be converted to water-insoluble by ther-mal imidization of water-soluble poly(amic acid)salt precursors,which endows the composites with low hygroscopicity.The coating containing MMT can protect against polyurethane(PU)foam fromfire.During the conical calorimetric test,the coated sample self-extinguished,and the peak heat release rate,total heat release,and total smoke production are significantly decreased by 53.39%,40.69%,and 53.03%,respectively.Taking advantage of these properties,this work utilizes a facile method to prepare biomimetic composites with low moisture absorption,excellent gas barrier properties,andflame retardancy,which have great application potential.
基金financially supported by the National Natural Science Foundation of China(No.21376276)the Specialfunded Program on National Key Scientific Instruments and Equipment Development of China(No.2012YQ230043)+1 种基金Guangdong Province Sci&Tech Bureau(Key Strategic Project No.2008A080800024)the Fundamental Research Funds for the Central Universities
文摘Relatively well crystallized and high aspect ratio Mg-Al layered double hydroxides(LDHs) were prepared by coprecipitation process in aqueous solution and further rehydrated to an organic modified LDH(OLDH) in the presence of surfactant. The intercalated structure and high aspect ratio of OLDH were verified by X-ray diffraction(XRD) and scanning electron microscopy(SEM). A series of poly(propylene carbonate)(PPC)/OLDH composite films with different contents of OLDH were prepared via a melt-blending method. Their cross section morphologies, gas barrier properties and tensile strength were investigated as a function of OLDH contents. SEM results show that OLDH platelets are well dispersed within the composites and oriented parallel to the composite sheet plane. The gas barrier properties and tensile strength are obviously enhanced upon the incorporation of OLDH. Particularly, PPC/2%OLDH film exhibits the best barrier properties among all the composite films. Compared with pure PPC, the oxygen permeability coefficient(OP) and water vapor permeability coefficient(WVP) is reduced by 54% and 17% respectively with 2% OLDH addition. Furthermore, the tensile strength of PPC/2%OLDH is 83% higher than that of pure PPC with only small lose of elongation at break. Therefore, PPC/OLDH composite films show great potential application in packaging materials due to its biodegradable properties, superior oxygen and moisture barrier characteristics.
基金National Natural Science Foundation of China(No.11872179)Science and Technology Planning Project of Fujian Province(No.2018H6024)+4 种基金Natural Science Foundation of Hunan Province(No.2019JJ50132)High-Level Talents Support Plan of Xiamen University of Technology(No.YKJ19008R)Open Fund for Innovation Platform of University in Hunan Province,China(No.18K079)Open Fund of Fujian Provincial Key Laboratory of Functional Materials and Applications(Xiamen University of Technology)China(No.fma2018004,No.fma2017110).
文摘In this study,polypyrrole-silver coated layered double hydroxides(LDHs@PPy-Ag)was prepared by chemical polymerization of pyrrole(Py)with silver ions.Silver nanoparticles(AgNPs)could be uniformly reduced onto PPy coatings in situ by redox reaction during simultaneous polymerization process.And LDHs@PPy-Ag/poly(ε-caprolactone)(PCL)nanocomposites were fabricated by solution casting method.It is revealed that spherical AgNPs are loaded on PPy coatings uniformly.Particularly,compared with pure PCL,LDHs@PPy-Ag/PCL nanocomposites with incorporation of only 1 wt%LDHs@PPy-Ag show a 17%increase in tensile strength(36.5 MPa)and a 29%increase in elongation at break(822%).Upon PPy-Ag coatings onto original LDHs,oxygen relative permeability of LDHs@PPy-Ag/PCL nanocomposites decreases to 52%with the same addition.Meanwhile,due to the double antibacterial activity of PPy and AgNPs,the antibacterial rate of LDHs@PPy-Ag reaches 100%.And the corresponding LDHs@PPy-Ag/PCL nanocomposites also show outstanding antibacterial activity.Considering the superiority of their comprehensive performance,antibacterial LDHs@PPy-Ag/PCL nanocomposites can be used further for the application as biodegradable polymeric active packaging materials.
基金financially supported by the National Key Research and Development Program of China(No.2018YFB0704200)the National Natural Science Foundation of China(Nos.51803140,52033005,51822305 and 21776186)+2 种基金the Science and Technology Department of Sichuan Province(No.2018JY0584)the Postdoctoral Science Foundation of China(No.2019M663496)the State Key Laboratory of Polymer Materials Engineering(No.sklpme2021-4-03)。
文摘It is a daunting task to develop a promising strategy at an industrial scale for simultaneously ameliorating ductility and gas barrier performance of poly(lactic acid)(PLA)films in the application of green packaging.In this work,biaxial stretching and constrained annealing were employed to prepare transparent PLA films with superior ductility and barrier properties.The oriented nano-sized crystals induced by biaxial stretching were developed into regularαform during constrained annealing,which could not only serve as“nano-barrier wall”to impede the diffusion and dissolution of gas molecules,but also strengthen amorphous chain entanglement network as physical crosslink to enhance ductility.As a result,the as-prepared PLA films exhibited an outstanding comprehensive performance with a low oxygen and water vapor permeability coefficient of 0.733×10^(-14) cm^(3)·cm·cm^(-2)·s^(-1)·Pa^(-1) and 3.82×10^(-14) g·cm·cm^(-2)·s^(-1)·Pa^(-1),respectively,outstanding ductility with elongation at break of 66.0%,high yield strength of 84.2 MPa,and good transparency of more than 80%at 550 nm.The new insight in the relationship between microscopic amorphous and crystalline structure and macroscopic performance is conducive to alleviating the intrinsic defects of brittle and insufficient barrier PLA films without the aid of any heterogenous modifiers,facilitating their widespread commercialization in the booming sustainable packaging market.
基金This work was financially supported by the National Natural Science Foundation of China(No.51673195).
文摘Poly(propylene carbonate) (PPC), the copolymerization product of carbon dioxide and propylene oxide, was chlorinated for the first time in our laboratory. Nuclear magnetic resonance (NMR) spectroscopy and ion chromatography test showed that chlorine atoms were successfully introduced onto the polymer chains of PPC. We named this newborn polymer material as chlorinated poly(propylene carbonate) (CPPC). It is worth noting that the reaction conditions of the chlorination of PPC were quite mild, which could be easily and simply realized at industrial level. What is more important is that CPPC possessed many more distinguished properties in solubility, wettability, adhesiveness, and gas barrier compared with PPC. For example, the bonding strength of CPPC as thermal adhesive is nearly four times higher than that of PPC for wood, stainless steel and glass. The oxygen permeability coefficient of CPPC exhibits a decrease of 33% compared with that of PPC. Moreover, CPPC is quite stable in air, whereas it could be well biodegraded in soil compared with PPC. These results indicated that CPPC could be widely used in the fields of coating, adhesive, barrier materials and so on, which could greatly promote the development of PPC industry.