Melamine formaldehyde foam(MFF)generates many poisonous chemicals through the traditional recycling methods for organic resin wastes.Herein,a high MFF degradation ratio of ca.97 wt.%was achieved under the mild conditi...Melamine formaldehyde foam(MFF)generates many poisonous chemicals through the traditional recycling methods for organic resin wastes.Herein,a high MFF degradation ratio of ca.97 wt.%was achieved under the mild conditions(160℃)in a NaOH–H2O system with ammelide and ammeline as the main degradation products.The alkaline solvent had an obvious corrosion effect for MFF,as indicated by scanning electron microscopy(SEM).The reaction process and products distribution were studied by Fourier-transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),and ^(13)C nuclear magnetic resonance(NMR).Besides,the MFF degradation products that have the similar chemical structures and bonding performances to those of melamine can be directly used as the raw material for synthesis of melamine urea-formaldehyde resins(MUFs).Moreover,the degradation system demonstrated here showed the high degradation efficiency after reusing for 7 times.The degradation process generated few harmful pollutants and no pre-or post-treatments were required,which proves its feasibility in the safe removal or recovery of waste MFF.展开更多
The development of multifunctional and efficient electromagnetic wave absorbing materials is a challenging research hotspot.Here,the magnetized Ni flower/MXene hybrids are successfully assembled on the surface of mela...The development of multifunctional and efficient electromagnetic wave absorbing materials is a challenging research hotspot.Here,the magnetized Ni flower/MXene hybrids are successfully assembled on the surface of melamine foam(MF)through electrostatic self-assembly and dip-coating adsorption process,realizing the integration of microwave absorption,infrared stealth,and flame retardant.Remarkably,the Ni/MXene-MF achieves a minimum reflection loss(RLmin)of−62.7 dB with a corresponding effective absorption bandwidth(EAB)of 6.24 GHz at 2 mm and an EAB of 6.88 GHz at 1.8 mm.Strong electromagnetic wave absorption is attributed to the three-dimensional magnetic/conductive networks,which provided excellent impedance matching,dielectric loss,magnetic loss,interface polarization,and multiple attenuations.In addition,the Ni/MXene-MF endows low density,excellent heat insulation,infrared stealth,and flame-retardant functions.This work provided a new development strategy for the design of multifunctional and efficient electromagnetic wave absorbing materials.展开更多
Melamine formaldehyde (MF) foam is kind of fire-retardant material and has great potential in acoustic and thermal insulation area. In this article, MF resin foam was prepared by microwave radiation. We discussed the ...Melamine formaldehyde (MF) foam is kind of fire-retardant material and has great potential in acoustic and thermal insulation area. In this article, MF resin foam was prepared by microwave radiation. We discussed the thermal stability of MF foam and the effect of different emulsifiers on its morphology, apparent density, fire-retardancy and mechanical property. The decomposition temperature of MF foam we prepared is nearly 400℃ and the constitution of residue after combustion is made up of carbon and graphite. Emulsifier influenced the apparent density of MF foam and using coemulsifiers can get flexible foam with uniform cell size, good morphology and low apparent density. When the fire-retardant MF foam’s apparent density is low of 5.53 kg/cm-3, its value of LOI can reach 32.4. The mechanical property of foam is consistent with apparent density.展开更多
The leakage of organic phase change materials(OPCMs)at temperatures above their melting point severely limits their large-scale application.The introduction of porous supports has been identified as an efficient leaka...The leakage of organic phase change materials(OPCMs)at temperatures above their melting point severely limits their large-scale application.The introduction of porous supports has been identified as an efficient leakageproofing method.In this study,a novel carbonized Cu-coated melamine foam(MF)/reduced graphene oxide(rGO)framework(MF/rGO/Cu-C)is constructed as a support for fabricating stabilized multifunctional OPCMs.MF serves as the supporting material,while rGO and Cu act as functional reinforcements.As a thermal energy storage material,polyethylene glycol(PEG)is encapsulated into MF/rGO/Cu-C through a vacuum-assisted impregnation method to obtain PEG@MF/rGO/Cu-C composite with excellent comprehensive performance.PEG@MF/rGO/Cu-C exhibits high phase change enthalpies of 148.3 J g^(-1)(melting)and 143.9 J g^(-1)(crystallization),corresponding to a high energy storage capability of 92.7%.Simultaneously,MF/rGO/Cu-C endues the composite with an enhanced thermal conductivity of 0.4621Wm^(-1) K^(-1),which increases by 463%compared to that of PEG@MF.Furthermore,PEG@MF/rGO/Cu-C displays great light-to-thermal and electric-to-thermal conversion capabilities,thermal cycle stability,light-tothermal cycle stability,and shape stability,showing promising application prospects in different aspects.展开更多
采用硬脂酰氯对三聚氰胺进行酰胺化改性得到十七烷基链修饰的三聚氰胺衍生物(酰胺化三聚氰胺),进而与甲醛、混合醇等进行加成、缩聚反应,制备了酰胺化密胺树脂,并将其制备成膜及硬泡材料,采用FTIR、NMR、TG、SEM及EDS对酰胺化三聚氰胺...采用硬脂酰氯对三聚氰胺进行酰胺化改性得到十七烷基链修饰的三聚氰胺衍生物(酰胺化三聚氰胺),进而与甲醛、混合醇等进行加成、缩聚反应,制备了酰胺化密胺树脂,并将其制备成膜及硬泡材料,采用FTIR、NMR、TG、SEM及EDS对酰胺化三聚氰胺、酰胺化密胺树脂以及膜层与硬泡材料进行了表征。结果表明,疏水烷基长链的引入使酰胺化三聚氰胺与水的接触角由改性前的0°升至133.5°以上;随着三聚氰胺酰胺化程度的提高,酰胺化密胺树脂的水容忍点温度逐渐降低,树脂黏度逐渐增大,不溶性颗粒逐渐增多增大。相对于常规密胺树脂制备的材料,酰胺化密胺树脂(无论是膜层材料还是硬泡材料)力学性能均未出现明显降低,样块抗压强度可达39.5 MPa,硬泡材料弯曲强度可达345.8 kPa,压缩强度可达315 k Pa,同时表现出优异的抗水和疏水效果,样块24h吸水率仅为1.1%,硬泡材料的体积吸水率降低至2.0%,膜层水接触角提高至107.5°,抗污染性能得到改善。展开更多
钯的富集常用泡塑作为载体,而通常对泡塑的处理过程需要使用带有胺基的有机试剂,以确保泡塑的官能团带有正电荷,用于富集带有负电荷的钯络阴离子。将样品用HCl-H 2 O 2体系进行消解,避免NO 3-的引入。将消解好的样品溶液用10%(V/V)盐酸...钯的富集常用泡塑作为载体,而通常对泡塑的处理过程需要使用带有胺基的有机试剂,以确保泡塑的官能团带有正电荷,用于富集带有负电荷的钯络阴离子。将样品用HCl-H 2 O 2体系进行消解,避免NO 3-的引入。将消解好的样品溶液用10%(V/V)盐酸处理过的三聚氰胺富集,在盐酸浓度低于10%(V/V),振荡时间为80 min时,选择高温灰化法,Pd的加标回收率可达到95%以上,相对标准偏差(RSD)为3.7%~6.8%。以铂族元素国家一级标准物质进行验证,测定值与认定值基本一致。泡塑富集处理过程简单易实现,且对环境友好,可以满足大部分矿样中Pd的分析检测。展开更多
基金supported by the National Natural Science Foundation of China(No.21774139)China,Key Research and Development Program of Shanxi Province,China(No,202102040201009)special fund of Beijing Key Laboratory of Clean Fuels and Efficient Catalytic Emission Reduction Technology and the Fund for Shanxi“1331 Project”.Thanks to Ningbo Kejiang Culture Sci.&Tech.Development Co.,Ltd.for the help in schematic drawing。
文摘Melamine formaldehyde foam(MFF)generates many poisonous chemicals through the traditional recycling methods for organic resin wastes.Herein,a high MFF degradation ratio of ca.97 wt.%was achieved under the mild conditions(160℃)in a NaOH–H2O system with ammelide and ammeline as the main degradation products.The alkaline solvent had an obvious corrosion effect for MFF,as indicated by scanning electron microscopy(SEM).The reaction process and products distribution were studied by Fourier-transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),and ^(13)C nuclear magnetic resonance(NMR).Besides,the MFF degradation products that have the similar chemical structures and bonding performances to those of melamine can be directly used as the raw material for synthesis of melamine urea-formaldehyde resins(MUFs).Moreover,the degradation system demonstrated here showed the high degradation efficiency after reusing for 7 times.The degradation process generated few harmful pollutants and no pre-or post-treatments were required,which proves its feasibility in the safe removal or recovery of waste MFF.
基金The authors thank National Natural Science Foundation of China(51803190)National Key R&D Program of China(2019YFA0706802)financial support.
文摘The development of multifunctional and efficient electromagnetic wave absorbing materials is a challenging research hotspot.Here,the magnetized Ni flower/MXene hybrids are successfully assembled on the surface of melamine foam(MF)through electrostatic self-assembly and dip-coating adsorption process,realizing the integration of microwave absorption,infrared stealth,and flame retardant.Remarkably,the Ni/MXene-MF achieves a minimum reflection loss(RLmin)of−62.7 dB with a corresponding effective absorption bandwidth(EAB)of 6.24 GHz at 2 mm and an EAB of 6.88 GHz at 1.8 mm.Strong electromagnetic wave absorption is attributed to the three-dimensional magnetic/conductive networks,which provided excellent impedance matching,dielectric loss,magnetic loss,interface polarization,and multiple attenuations.In addition,the Ni/MXene-MF endows low density,excellent heat insulation,infrared stealth,and flame-retardant functions.This work provided a new development strategy for the design of multifunctional and efficient electromagnetic wave absorbing materials.
文摘Melamine formaldehyde (MF) foam is kind of fire-retardant material and has great potential in acoustic and thermal insulation area. In this article, MF resin foam was prepared by microwave radiation. We discussed the thermal stability of MF foam and the effect of different emulsifiers on its morphology, apparent density, fire-retardancy and mechanical property. The decomposition temperature of MF foam we prepared is nearly 400℃ and the constitution of residue after combustion is made up of carbon and graphite. Emulsifier influenced the apparent density of MF foam and using coemulsifiers can get flexible foam with uniform cell size, good morphology and low apparent density. When the fire-retardant MF foam’s apparent density is low of 5.53 kg/cm-3, its value of LOI can reach 32.4. The mechanical property of foam is consistent with apparent density.
基金National Natural Science Foundation of China,Grant/Award Numbers:51861005,52071092,U20A20237Guangxi Natural Science Foundation,Grant/Award Numbers:2019GXNSFDA245023,2019GXNSFGA245005,2020GXNSFGA297004,2021GXNSFFA196002Guangxi Bagui Scholar Foundation。
文摘The leakage of organic phase change materials(OPCMs)at temperatures above their melting point severely limits their large-scale application.The introduction of porous supports has been identified as an efficient leakageproofing method.In this study,a novel carbonized Cu-coated melamine foam(MF)/reduced graphene oxide(rGO)framework(MF/rGO/Cu-C)is constructed as a support for fabricating stabilized multifunctional OPCMs.MF serves as the supporting material,while rGO and Cu act as functional reinforcements.As a thermal energy storage material,polyethylene glycol(PEG)is encapsulated into MF/rGO/Cu-C through a vacuum-assisted impregnation method to obtain PEG@MF/rGO/Cu-C composite with excellent comprehensive performance.PEG@MF/rGO/Cu-C exhibits high phase change enthalpies of 148.3 J g^(-1)(melting)and 143.9 J g^(-1)(crystallization),corresponding to a high energy storage capability of 92.7%.Simultaneously,MF/rGO/Cu-C endues the composite with an enhanced thermal conductivity of 0.4621Wm^(-1) K^(-1),which increases by 463%compared to that of PEG@MF.Furthermore,PEG@MF/rGO/Cu-C displays great light-to-thermal and electric-to-thermal conversion capabilities,thermal cycle stability,light-tothermal cycle stability,and shape stability,showing promising application prospects in different aspects.
文摘采用硬脂酰氯对三聚氰胺进行酰胺化改性得到十七烷基链修饰的三聚氰胺衍生物(酰胺化三聚氰胺),进而与甲醛、混合醇等进行加成、缩聚反应,制备了酰胺化密胺树脂,并将其制备成膜及硬泡材料,采用FTIR、NMR、TG、SEM及EDS对酰胺化三聚氰胺、酰胺化密胺树脂以及膜层与硬泡材料进行了表征。结果表明,疏水烷基长链的引入使酰胺化三聚氰胺与水的接触角由改性前的0°升至133.5°以上;随着三聚氰胺酰胺化程度的提高,酰胺化密胺树脂的水容忍点温度逐渐降低,树脂黏度逐渐增大,不溶性颗粒逐渐增多增大。相对于常规密胺树脂制备的材料,酰胺化密胺树脂(无论是膜层材料还是硬泡材料)力学性能均未出现明显降低,样块抗压强度可达39.5 MPa,硬泡材料弯曲强度可达345.8 kPa,压缩强度可达315 k Pa,同时表现出优异的抗水和疏水效果,样块24h吸水率仅为1.1%,硬泡材料的体积吸水率降低至2.0%,膜层水接触角提高至107.5°,抗污染性能得到改善。
