Nanofiltration(NF) technology,with its capacity for nanoscale filtration and controllable selectivity,holds significant promise in diverse applications.However,the current upper bound of permeance and selectivity of N...Nanofiltration(NF) technology,with its capacity for nanoscale filtration and controllable selectivity,holds significant promise in diverse applications.However,the current upper bound of permeance and selectivity of NF membranes is intrinsically constrained by the morphology and structure of the polyamide(PA) selective layer.This issue arises because NF membranes typically exhibit relatively smooth nodular structures,which theoretically impede efficient water transport.In this study,we enhanced the formation of nanobubbles by synergistically regulating with surfactant and low temperatures,resulting in the fabrication of PA NF membranes with a crumpled morphology.We observed that lower temperatures promote enhanced gas solubility in the aqueous phase,facilitating increased nanobubble formation through the foaming effect of surfactant sodium dodecylbenzene sulfonate(SDBS).Consequently,this resulted in the creation of PA NF membranes with more crumpled structures and superior performance,with pure water permeance reaching 36.25 ± 0.42 L m^(-2)h^(-1)bar^(-1),representing an improvement of 14.47 L m^(-2)h^(-1)bar^(-1)compared to the control group.Additionally,it maintains a high Na_(2)SO_(4) rejection rate of97.00 % ± 0.58 %.The PA NF membranes produced by eliminating nanobubbles and free interfaces exhibited a smooth structure,whereas introducing nanobubbles(through Na HCO_(3) addition,N_(2) pressurization,and ultrasonication) resulted in the formation of crumpled membranes.This emphasized that the large amount of nanobubbles generated by SDBS and low temperature in the interfacial process played a critical role in shaping crumpled PA NF membranes and enhancing membrane performance.This approach has the potential to provide valuable insights into customizing the structural design of TFC PA NF membranes,contributing to further advancements in this field.展开更多
Triboelectric nanogenerators(TENGs)are a feasible solution to the energy shortage.As a high performance engineering thermoplastic,polyamides(PAs)have often been used as triboelectric materials of TENGs.However,most ex...Triboelectric nanogenerators(TENGs)are a feasible solution to the energy shortage.As a high performance engineering thermoplastic,polyamides(PAs)have often been used as triboelectric materials of TENGs.However,most existing PAs are synthesized from petroleum-based monomers,and their production processes involve greenhouse gas emissions,which conflict with the sustainable development of TENGs.Accordingly,the research on biobased PAs has attracted increasing attention.Herein,heat-resistant semi-aromatic polyamide(HR-PA)was designed and synthesized from terephthalic acid,butylenediamine,and biobased pentanediamine.HR-PA exhibited outstanding thermal properties in terms of glass transition temperature(T_(g)~130℃),melting point(T_(m)~308℃)and initial decomposition temperature at weight loss of 5%(T_(d)^(5wt%)~436℃).The heat-resistant triboelectric nanogenerator(HR-TENG)was fabricated with HR-PA and high thermal conductivity filler hexagonal boron nitride(h-BN).Introduction of h-BN with good thermal dissipation,the resultant HR-TENG possessed excellent electronic output performances at elevated temperatures,for instance,maximum open-circuit voltage(V_(oc))~90 V,short-circuit current(I_(sc))~8.7μA,and shortcircuit charge(Q_(sc))~30 nC at 150℃.Consequently,this work paves the way for developing HR-TENG that can be integrated into firefighting protective clothing systems for real-time physiological health monitoring.展开更多
The chemical structure of polyamide 6(PA6)dictates that only 50%of hydrogen bonds participate in crystallization during the crystallization process,resulting in the properties of its products being significantly depen...The chemical structure of polyamide 6(PA6)dictates that only 50%of hydrogen bonds participate in crystallization during the crystallization process,resulting in the properties of its products being significantly dependent on the molding process.Therefore,the design and development of nucleating agents suitable for PA6 holds great practical significance for high-performance PA6 materials.Amide-based nucleating agents can effectively improve the crystallization rate by increasing intermolecular hydrogen bond density.Further introduction of hydroxyl groups can enhance the hydrogen bonding interactions between the nucleating agent and PA6.In this study,a hydroxyl-containing amidebased nucleating agent,BHT,was designed and synthesized using a tyramine-based biomass as the raw material.These results demonstrated that BHT exhibited good structural compatibility with PA6.After adding 1 wt%BHT,the crystallization temperature of PA6 increased from 170.9℃to 193.3℃,the crystallinity increased 16.6%,the heat distortion temperature and Vicat softening temperature rose to 89.5 and 187.8℃,respectively,the haze decreased to 46%,achieving the synergistic optimization of mechanical,thermal,and optical properties.The in situ time-resolved FTIR results indicated that the addition of BHT increased the enthalpy of hydrogen bond formation during the nucleation stage,facilitated the segmental conformation adjustment of PA6,and enhanced the molar concentration of trans-conformations,ultimately leading to an improvement in the crystallization rate.展开更多
Carbon fibres have been produced from hydroxypropyl-modified lignin(TcC)/bio-based polyamide 1010(PA1010)blended filaments.Two grades of PA1010,with different molecular weights and rheological properties,were used for...Carbon fibres have been produced from hydroxypropyl-modified lignin(TcC)/bio-based polyamide 1010(PA1010)blended filaments.Two grades of PA1010,with different molecular weights and rheological properties,were used for blending with TcC.An oxidative thermal stabilisation step was used prior to carbonisation in an inert atmosphere to prevent the fusion of the filaments during the latter step.Thermal stabilisation was not possible using a one-step stabilisation process reported in the literature for lignin and other lignin/synthetic polymer blends.As a consequence,a cyclic process involving an additional isothermal phase at a lower temperature than the precursor filaments’melting point,was introduced to increase the cross-linking reactions between the lignin and polyamide.Thermally stabilised filaments were characterised by DSC,TGA,TGA-FTIR,ATR,and SEM techniques.Polymer rheology and heating rate used during thermal stabilisation influenced the thermal stabilisation process and mechanical properties of the derived filaments.Thermally stabilised filaments using optimised conditions(heating in the air atmosphere at 0.25℃/min to 180℃;isothermal for 1 h,cooling back down to ambient at 5℃/min;heating to 250℃ at 0.25℃/min,isothermal for 2 h)could be successfully carbonised.Carbon fibres pro-duced had void-free morphologies and mechanical properties comparable to similarly thermally stabilised and carbonised polyacrylonitrile(PAN)filaments.展开更多
The fabrication of highly flame-retardant polyamide 6(PA6)composites is of great significance for expanding their practical applications.Herein,a new flame-retardant system(ADP/FA)was developed by combining aluminum d...The fabrication of highly flame-retardant polyamide 6(PA6)composites is of great significance for expanding their practical applications.Herein,a new flame-retardant system(ADP/FA)was developed by combining aluminum diethylphosphinate(ADP)with excellent flame retardancy and fly ash(FA),an economical and environmentally friendly industrial waste.Due to the synergistic flame-retardant effect of ADP/FA in the condensed phase and gas phase,the PA6 composite containing only 11 wt%of ADP/FA(mass ratio 93:7)obtained vertical burning(UL-94)tests V-0 rating with a limiting oxygen index(LOI)of 30.9%.To obtain the same flame-retardant level of PA6/ADP/FA-3,the loading amount of ADP alone was required 14 wt%.Compared with the PA6/ADP,the introduction of FA not only reduced the amount of flame retardant added but also inhibited the formation of molten droplets during combustion,greatly enhancing the fire safety of the PA6 composites.The flame-retardant performance of the ADP/FA system is superior to that of most current ADP-based synergistic strategies.In the meantime,the introduction of FA also significantly reduced the high smoke release caused by ADP flame retardant.The peak smoke production rate(pSPR)of the PA6 composite,from 0.221 m2⋅s-1(PA6/ADP)to 0.116 m2⋅s-1,represents a 47.5%decrease.This work provides a feasible solution for fabricating PA6 composites with excellent flame retardancy.展开更多
Environmental concerns over synthetic dyes,including water pollution and high energy demands,have driven interest in sustainable alternatives.This research investigates the colouration of polyamide 6(nylon 6)textiles ...Environmental concerns over synthetic dyes,including water pollution and high energy demands,have driven interest in sustainable alternatives.This research investigates the colouration of polyamide 6(nylon 6)textiles using a natural dye derived from the mature pods of Cassia fistula,which serve as a source of anthraquinone-based pigments.The study systematically evaluated the influence of dyeing parameters-namely temperature(30-90℃),duration(10-60 min),pH range(4-11),dye concentration(10%-70%owf),and post-mordanting using alum,ferrous sulfate,and stannous chloride-on the resulting colour strength(K/S)and CIE Lab*coordinates.The fastness characteristics of polyamide 6 fabric were assessed,with the corresponding results detailed in the subsequent sections.Maximum dye absorption was achieved at 90℃for 60 minutes under acidic conditions(pH 4),and from the conditions was given K/S 2.242.An increase in dye concentration led to higher K/S values,which were further augmented by mordanting,with aluminum potassium sulfate and stannous chloride yielding the greatest results.Colour fastness assessments indicated good to excellent resistance to washing,water exposure,rubbing,and perspiration,all of the properties were up to 4.Whereas resistance to light was found from 1 to 2.The findings confirm Cassia fistula extract as a renewable,eco-friendly dye for polyamide 6,offering commercially viable colour strength and fastness while supporting sustainable textile processing.展开更多
In this paper,polyamide(PA)woven fabric was used as the base fabric,and polyurethane(PU)solution containing silica nanoparticles(PU@SiO_(2)NPs)was used as the coating solution to prepare composite tent fabric(PA/PU@Si...In this paper,polyamide(PA)woven fabric was used as the base fabric,and polyurethane(PU)solution containing silica nanoparticles(PU@SiO_(2)NPs)was used as the coating solution to prepare composite tent fabric(PA/PU@SiO_(2)).The morphology,structure,and durability of the tent fabric under ultraviolet(UV)radiation,waterstained,or thermal conditions were investigated.The results show that compared with PA/PU fabric without SiO_(2)NPs,when the mass fraction of SiO_(2)NPs in PU coating is 5%,the air permeability of PA/PU@SiO_(2)fabric decreases from about 7.5 to 6.0 nm/s,while the reflectivity to UVvisible light is significantly improved.The surface wettability decreases,as indicated by the average water contact angle(WCA)on PA/PU@SiO_(2)remaining stable at 47°after 9 min.After thermal treatment,the PA/PU@SiO_(2)fabric shows superior mechanical stability.The degradation rate of the tensile strength is only 6.3%,approximately half that of the PA/PU fabric.Meanwhile,the elongation at break increases to 98.9%,compared to 61.8%for the PA/PU fabric.展开更多
Lithium extraction from salt lakes has become an environmentally friendly way of lithium acquisition.The development of new nanofiltration membrane is significant to enhance the separation efficiency of lithium from a...Lithium extraction from salt lakes has become an environmentally friendly way of lithium acquisition.The development of new nanofiltration membrane is significant to enhance the separation efficiency of lithium from a high Mg^(2+)/Li^(+) mass ratio brine.In this work,Fe^(3+)/tannic acid-trimesoyl chloride-polyetherimide(Fe^(3+)/TA-TMC-PEI) composite nanofiltration membranes were designed to study the separation performance of Mg^(2+)/Li^(+) in a high Mg^(2+)/Li^(+) mass ratio simulated brine.Fe^(3+)/TA separation layer was introduced through the rapid assembly of tannic acid and coordination mediated by Fe^(3+)on polyethersulfone supporting membrane.The polyamide layer was prepared through the reverse interfacial polymerization between TMC and PEI.The composite nanofiltration membrane has high crosslinking degree and positive charge and low pore size.The best performance of the composite nanofiltration membrane was obtained with 0.3%(mass) Fe^(3+) solution,0.9%(mass) TA,and 2 g·L^(-1) PEI 600ethanol solution.The retention of bivalent ions was significantly greater than that of monvalent ions in single salt solution.The Fe^(3+)/TA-TMC-PEI composite nanofiltration membrane showed a stable separation factor of 12.02 when the Mg^(2+)/Li^(+) mass ratio was 120 in the mixed salt solution.This work deepens the understanding of the mechanism of lithium extraction in magnesia-lithium system,and the modification strategy provides a possible guide for the design of Mg^(2+)/Li^(+) separation membranes with practical potential from the perspective of lithium extraction technology.展开更多
Long-chain polyamides(LCPAs)are a class of bio-based polymers that can bridge conventional polyolefins and polycondensates.In this work,taking the advantage of the amphiphilic nature of polyamide 1012(PA1012),membrane...Long-chain polyamides(LCPAs)are a class of bio-based polymers that can bridge conventional polyolefins and polycondensates.In this work,taking the advantage of the amphiphilic nature of polyamide 1012(PA1012),membranes were prepared by using a non-conventional phase separation approach,namely,mixed‘non-solvents’evaporation induced phase separation(MNEIPS).PA1012 can be dissolved in a mixture of polar and non-polar solvents,both of which are non-solvents of PA1012.During the sequential evaporation of the two solvents,the phase separation of PA1012 occurred,inducing the formation of porous structures.We investigated the process of membrane formation in detail,with a specific focus on the liquid-liquid and liquid-solid phase transitions involved.Moreover,we studied the influence of critical factors,such as polymer concentration and mixed-solvent ratio,on the morphologies and properties of PA1012 membranes.This study provides new insights into the development of porous materials based on long-chain polycondensates.展开更多
Two master-batches,polyamide 66 (PA66)/organo-montmorillonite (OMMT) and polyamide 6 (PA6)/OMMT, prepared by melt compounding with methyl methacrylate (MMA) as co-intercalation agent,have been used to prepare nearly e...Two master-batches,polyamide 66 (PA66)/organo-montmorillonite (OMMT) and polyamide 6 (PA6)/OMMT, prepared by melt compounding with methyl methacrylate (MMA) as co-intercalation agent,have been used to prepare nearly exfoliated PA661montmorillonite (MMT) nanocomposites.The resulting nanocomposites are compared in view of their morphology and properties.Nano-scale dispersion of OMMT is realized in both types of nanocomposites,as revealed by XRD,TEM and Molau tests.PA66/MMT nanocomposites having superior mecha...展开更多
An improved method for preparing melamine cyanurate （MCA） based flame retardant polyamide 6 （FRPA6） materials has been proposed. This processing method, i.e., improved in situ polymerization, was used to synthesiz...An improved method for preparing melamine cyanurate （MCA） based flame retardant polyamide 6 （FRPA6） materials has been proposed. This processing method, i.e., improved in situ polymerization, was used to synthesize flame retardant PA6. In situ formed MCA nanoparticles were supposed to be linked to PA6 chains in the ε-caprolactam hydrolytic polymerization system to obtain startype polymers for the first time. Through TEM photographs, it can be found that the in situ formed MCA nanoparticles with diametric size of less than 50 nm, are nanoscaled, highly uniformly dispersed in the PA6 matrix. Synthesized flame retardant PA6 have good fire performance which can achieve UL-94 V-0 rating at 1.6 mm thickness with the presence of 7.34 wt.% MCA in the matrix.展开更多
Novel bio-based and biodegradable block copolymers were synthesized by "click" reaction between poly(L-lactide)(PLLA) and polyamide 4(PA4). Upon tuning the molar mass of PLLA block, the properties of copolym...Novel bio-based and biodegradable block copolymers were synthesized by "click" reaction between poly(L-lactide)(PLLA) and polyamide 4(PA4). Upon tuning the molar mass of PLLA block, the properties of copolymers and electrospun ultrafine fibers were investigated and compared with those of PLLA and PA4 blends. PLLA and PA4 were found incompatible and formed individual crystalline regions, along with reciprocal inhibition in crystallization. Electrospun fibers were highly hydrophobic, even if hydrophilic PA4 was the rich component. The crystallinity of either PLLA or PA4 decreased after electrospinning and PLLA-rich as-spun fibers were almost amorphous. Immersion tests proved that fibers of block copolymers were relatively homogeneous with micro-phase separation between PLLA and PA4. The fibrous structures of copolymers were different from those of the fibers electrospun from blends, for which sheath-core structure induced by macro-phase separation between homopolymers of PLLA and PA4 was confirmed by TEM, EDS, and XPS.展开更多
A diamine containing ether and ester units, as basic monomer for the preparation of polyamides, was prepared via three consecutive reactions. Nucleophilic substitution reaction of 1,4-dihydroxy benzene with 4-nitroben...A diamine containing ether and ester units, as basic monomer for the preparation of polyamides, was prepared via three consecutive reactions. Nucleophilic substitution reaction of 1,4-dihydroxy benzene with 4-nitrobenzoyl chloride produced 4-hydroxyphenyl 4-nitrobenzoate （HPNB）. Reduction of nitro groups to amino groups using Fe and HC1 resulted in preparation of 4-hydroxyphenyl 4-aminobenzoate （HPAB）. The diamine was synthesized through nucleophilic substitution reaction of HPAB with 2,6-dichloropyridine. The precursors and diamine were fully characterized by common methods, and the diamine was polycondensed with different diacid chlorides in the presence of an acid scavenger to prepare new polyamides. The polyamides were characterized, and their physical properties including thermal stability and behavior, inherent viscosity and solubility were studied.展开更多
Polyamide 6 underwent an efficient depolymerization in hydrophilic ionic liquids under microwave irradiation at 300C. The depolymerization completed within 60 min. Caprolactam was readily separated by simple extractio...Polyamide 6 underwent an efficient depolymerization in hydrophilic ionic liquids under microwave irradiation at 300C. The depolymerization completed within 60 min. Caprolactam was readily separated by simple extraction procedure and the ionic liquids were recovered and reused for several times. Addition of catalytic amounts of DMAP(N,N-dimethylaminopyridine) promoted the depolymerization effectively.The present improved procedure provides a method to avoid direct distillation procedure, which consumes energy for the separation of caprolactam from ionic liquids. Although some contamination of ionic liquids was observed, the present procedure provides a new possibility for the use of ionic liquids for plastic chemical recycling from the viewpoint of development of an energy-saving methodology. Use of solubility switchable ionic liquids is also examined to explore a possibility for better separation although depolymerization did not work well.展开更多
Liquid crystalline polymer-polyamide 66 (LCP/PA66) blends were compounded by using a Brabender mixing followed by compression moulding. The LCP employed was a semi-flexible liquid crystalline copolyesteramide based o...Liquid crystalline polymer-polyamide 66 (LCP/PA66) blends were compounded by using a Brabender mixing followed by compression moulding. The LCP employed was a semi-flexible liquid crystalline copolyesteramide based on 30% (molar fraction ) of p-amino benzoic acid (ABA ) and 70% (molar fraction) of poly (ethylene terephthalate) (PET). The LCP/PA66 blends were investigated in terms of the thermal and dynamic mechanical properties. It was found that PA66 and LCP components of the blends are miscible in the molten state, but are partially miscible in the solid state. The inclusion of the semi-flexible LCP into PA66 retards the crystallization rate of PA66. Furthermore, the melting temperature and the degree of crystallinity of PA66 are reduced considerably due to the LCP addition.展开更多
Crosslinking treatments for a commercially available aromatic polyamide reverse osmosis membrane were carried out to improve its chlorine resistance.The crosslinking agents including 1,6-hexanediol diglycidyl ether,ad...Crosslinking treatments for a commercially available aromatic polyamide reverse osmosis membrane were carried out to improve its chlorine resistance.The crosslinking agents including 1,6-hexanediol diglycidyl ether,adipoyl dichloride and hexamethylene diisocyanate ester with long flexible aliphatic chains and high reactivity with N-H groups were used in the experiments.Attenuated total reflective Fourier transform infrared spectra verified the successful preparation of highly crosslinked membranes by crosslinking treatments.It was suggested that the crosslinking agents were connected to membrane surface through the reactions with amine and amide Ⅱ groups,which is confirmed by surface charge measurements.Based on contact angle measurements,crosslinking treatments decreased membrane hydrophilicity by introducing methylene groups to membrane surface.With increasing amount of crosslinking agent molecules connected to membrane surface,the hydrolysis of unconnected functional groups of crosslinking agent produced polar groups and increased membrane hydrophilicity.The highly crosslinked membranes showed higher salt rejections and lower water fluxes as compared with the raw membrane.Since the active sites(N-H groups) vulnerable to free chlorine on membrane surface were eliminated by crosslinking treatments,the chlorine resistances of the highly crosslinked membranes were significantly improved by slighter changes in both water fluxes and salt rejections after chlorination.展开更多
Long chain semiaromatic polyamides with high molecular weight were synthesized by the reactions of undecanediamine with various aromatic diacids,and characterized by fourier transform infrared spectra（FT-IR） and nuc...Long chain semiaromatic polyamides with high molecular weight were synthesized by the reactions of undecanediamine with various aromatic diacids,and characterized by fourier transform infrared spectra（FT-IR） and nuclear magnetic resonance（1H-NMR）.The thermal behaviors were determined by differential scanning calorimetry（DSC） and thermogravimetric analysis（TGA）.The solubility,dynamic mechanical,physical and mechanical properties of the polyamides were also investigated.The experimental results show that the polyamides with high molecular weights are obtained only the PH value of the polyamides salt are in the range of 7.2-7.4.The melting temperatures and the glass transition temperatures of the polyamides increase with the increase of the rigidity of aromatic diacids,and are near to those of poly（nonamethylenetere-phthalamide）（PA9T）.展开更多
In-situ composites based on dispersed poly (ethylene terephthalate) (PET) or polyamide (PA), and continuous polyethylene (PE) were prepared through a single screw extruder of Haake rheometer system with a rod-die rela...In-situ composites based on dispersed poly (ethylene terephthalate) (PET) or polyamide (PA), and continuous polyethylene (PE) were prepared through a single screw extruder of Haake rheometer system with a rod-die relatively small in diameter. The extrudate was drawn at a drawing ratio of 3.1, and then quickly cooled in cold water. The specimens were obtained by injection molding at processing temperatures less than 190℃, far below the melting temperature of PET (265℃) and PA (230℃), which can maintain the solid state of PET and PA microfiber phase in the composites. Morphological observation with scanning electron microscopy (SEM) indicated that PET and PA can more or less form in-situ microfibers at compositions studied (0~20 wt pct PET or PA), and especially, PET and PA were almost deformed into fibers at the concentration of 15 wt pct. Tensile strength and modulus of the blends reinforced by PET or PA microfibers showed to be increased from the tensile test results. The most noticeable improvement of the tensile properties occurred at 15 wt pct of PET in PET/PE system, corresponding to the highest microfiber content, where the tensile strength reached 32.5 MPa, whereas only 19.5 MPa for the pure PE.展开更多
Polyamide 11 (PA 11) is a widely used polyamide resin, but its application is limited since the impact properties, tensile strength, and thermal properties are not very satisfactory for industrial application. In orde...Polyamide 11 (PA 11) is a widely used polyamide resin, but its application is limited since the impact properties, tensile strength, and thermal properties are not very satisfactory for industrial application. In order to improve the mechanical properties of PA 11, in this paper, the preparation of polyamide 11/clay nanocomposites (PACN) via in-situ intercalated polymerization was reported. SEM, TEM and XRD were employed to investigate the dispersion of clay sheet in the matrix. The results indicate that clay layers were homogeneously dispersed in PA11 matrix on a nano-scale, and an exfoliated and intercalated structure co-existed in the composites. The mechanical and thermal properties of the obtained nanocomposites were improved to certain extent by the addition of clay.展开更多
A new hypocrellin B （HB） derivative bearing a bispyrrolecarboxamide-containing side chain was synthesized, which presents improved absorptivity in phototherapeufic window than HB and affinity feature towards dsDNA.
基金the National Natural Science Foundation of China (Nos.52430001,52470091,52200108) for the financial support。
文摘Nanofiltration(NF) technology,with its capacity for nanoscale filtration and controllable selectivity,holds significant promise in diverse applications.However,the current upper bound of permeance and selectivity of NF membranes is intrinsically constrained by the morphology and structure of the polyamide(PA) selective layer.This issue arises because NF membranes typically exhibit relatively smooth nodular structures,which theoretically impede efficient water transport.In this study,we enhanced the formation of nanobubbles by synergistically regulating with surfactant and low temperatures,resulting in the fabrication of PA NF membranes with a crumpled morphology.We observed that lower temperatures promote enhanced gas solubility in the aqueous phase,facilitating increased nanobubble formation through the foaming effect of surfactant sodium dodecylbenzene sulfonate(SDBS).Consequently,this resulted in the creation of PA NF membranes with more crumpled structures and superior performance,with pure water permeance reaching 36.25 ± 0.42 L m^(-2)h^(-1)bar^(-1),representing an improvement of 14.47 L m^(-2)h^(-1)bar^(-1)compared to the control group.Additionally,it maintains a high Na_(2)SO_(4) rejection rate of97.00 % ± 0.58 %.The PA NF membranes produced by eliminating nanobubbles and free interfaces exhibited a smooth structure,whereas introducing nanobubbles(through Na HCO_(3) addition,N_(2) pressurization,and ultrasonication) resulted in the formation of crumpled membranes.This emphasized that the large amount of nanobubbles generated by SDBS and low temperature in the interfacial process played a critical role in shaping crumpled PA NF membranes and enhancing membrane performance.This approach has the potential to provide valuable insights into customizing the structural design of TFC PA NF membranes,contributing to further advancements in this field.
基金supported by the National Key Research and Development Program of China(2021YFC2101800)the National Natural Science Foundation of China(52173117,52473004)+2 种基金the Natural Science Foundation of Shanghai(22ZR1400700)the Science and Technology Commission of Shanghai Municipality(20DZ2254900)the Fundamental Research Funds for the Central Universities(CUSF-DH-T-2023034)。
文摘Triboelectric nanogenerators(TENGs)are a feasible solution to the energy shortage.As a high performance engineering thermoplastic,polyamides(PAs)have often been used as triboelectric materials of TENGs.However,most existing PAs are synthesized from petroleum-based monomers,and their production processes involve greenhouse gas emissions,which conflict with the sustainable development of TENGs.Accordingly,the research on biobased PAs has attracted increasing attention.Herein,heat-resistant semi-aromatic polyamide(HR-PA)was designed and synthesized from terephthalic acid,butylenediamine,and biobased pentanediamine.HR-PA exhibited outstanding thermal properties in terms of glass transition temperature(T_(g)~130℃),melting point(T_(m)~308℃)and initial decomposition temperature at weight loss of 5%(T_(d)^(5wt%)~436℃).The heat-resistant triboelectric nanogenerator(HR-TENG)was fabricated with HR-PA and high thermal conductivity filler hexagonal boron nitride(h-BN).Introduction of h-BN with good thermal dissipation,the resultant HR-TENG possessed excellent electronic output performances at elevated temperatures,for instance,maximum open-circuit voltage(V_(oc))~90 V,short-circuit current(I_(sc))~8.7μA,and shortcircuit charge(Q_(sc))~30 nC at 150℃.Consequently,this work paves the way for developing HR-TENG that can be integrated into firefighting protective clothing systems for real-time physiological health monitoring.
文摘The chemical structure of polyamide 6(PA6)dictates that only 50%of hydrogen bonds participate in crystallization during the crystallization process,resulting in the properties of its products being significantly dependent on the molding process.Therefore,the design and development of nucleating agents suitable for PA6 holds great practical significance for high-performance PA6 materials.Amide-based nucleating agents can effectively improve the crystallization rate by increasing intermolecular hydrogen bond density.Further introduction of hydroxyl groups can enhance the hydrogen bonding interactions between the nucleating agent and PA6.In this study,a hydroxyl-containing amidebased nucleating agent,BHT,was designed and synthesized using a tyramine-based biomass as the raw material.These results demonstrated that BHT exhibited good structural compatibility with PA6.After adding 1 wt%BHT,the crystallization temperature of PA6 increased from 170.9℃to 193.3℃,the crystallinity increased 16.6%,the heat distortion temperature and Vicat softening temperature rose to 89.5 and 187.8℃,respectively,the haze decreased to 46%,achieving the synergistic optimization of mechanical,thermal,and optical properties.The in situ time-resolved FTIR results indicated that the addition of BHT increased the enthalpy of hydrogen bond formation during the nucleation stage,facilitated the segmental conformation adjustment of PA6,and enhanced the molar concentration of trans-conformations,ultimately leading to an improvement in the crystallization rate.
文摘Carbon fibres have been produced from hydroxypropyl-modified lignin(TcC)/bio-based polyamide 1010(PA1010)blended filaments.Two grades of PA1010,with different molecular weights and rheological properties,were used for blending with TcC.An oxidative thermal stabilisation step was used prior to carbonisation in an inert atmosphere to prevent the fusion of the filaments during the latter step.Thermal stabilisation was not possible using a one-step stabilisation process reported in the literature for lignin and other lignin/synthetic polymer blends.As a consequence,a cyclic process involving an additional isothermal phase at a lower temperature than the precursor filaments’melting point,was introduced to increase the cross-linking reactions between the lignin and polyamide.Thermally stabilised filaments were characterised by DSC,TGA,TGA-FTIR,ATR,and SEM techniques.Polymer rheology and heating rate used during thermal stabilisation influenced the thermal stabilisation process and mechanical properties of the derived filaments.Thermally stabilised filaments using optimised conditions(heating in the air atmosphere at 0.25℃/min to 180℃;isothermal for 1 h,cooling back down to ambient at 5℃/min;heating to 250℃ at 0.25℃/min,isothermal for 2 h)could be successfully carbonised.Carbon fibres pro-duced had void-free morphologies and mechanical properties comparable to similarly thermally stabilised and carbonised polyacrylonitrile(PAN)filaments.
基金financially supported by the Natural Science Foundation of China(52173069)the Key Research and Development Projects in Heilongjiang Province(2024ZXDXA29)+1 种基金the Natural Science Foundation of Heilongjiang Province(LH2024B004)the Fundamental Research Funds for the Central Universities(ZHLJZR241700006).
文摘The fabrication of highly flame-retardant polyamide 6(PA6)composites is of great significance for expanding their practical applications.Herein,a new flame-retardant system(ADP/FA)was developed by combining aluminum diethylphosphinate(ADP)with excellent flame retardancy and fly ash(FA),an economical and environmentally friendly industrial waste.Due to the synergistic flame-retardant effect of ADP/FA in the condensed phase and gas phase,the PA6 composite containing only 11 wt%of ADP/FA(mass ratio 93:7)obtained vertical burning(UL-94)tests V-0 rating with a limiting oxygen index(LOI)of 30.9%.To obtain the same flame-retardant level of PA6/ADP/FA-3,the loading amount of ADP alone was required 14 wt%.Compared with the PA6/ADP,the introduction of FA not only reduced the amount of flame retardant added but also inhibited the formation of molten droplets during combustion,greatly enhancing the fire safety of the PA6 composites.The flame-retardant performance of the ADP/FA system is superior to that of most current ADP-based synergistic strategies.In the meantime,the introduction of FA also significantly reduced the high smoke release caused by ADP flame retardant.The peak smoke production rate(pSPR)of the PA6 composite,from 0.221 m2⋅s-1(PA6/ADP)to 0.116 m2⋅s-1,represents a 47.5%decrease.This work provides a feasible solution for fabricating PA6 composites with excellent flame retardancy.
文摘Environmental concerns over synthetic dyes,including water pollution and high energy demands,have driven interest in sustainable alternatives.This research investigates the colouration of polyamide 6(nylon 6)textiles using a natural dye derived from the mature pods of Cassia fistula,which serve as a source of anthraquinone-based pigments.The study systematically evaluated the influence of dyeing parameters-namely temperature(30-90℃),duration(10-60 min),pH range(4-11),dye concentration(10%-70%owf),and post-mordanting using alum,ferrous sulfate,and stannous chloride-on the resulting colour strength(K/S)and CIE Lab*coordinates.The fastness characteristics of polyamide 6 fabric were assessed,with the corresponding results detailed in the subsequent sections.Maximum dye absorption was achieved at 90℃for 60 minutes under acidic conditions(pH 4),and from the conditions was given K/S 2.242.An increase in dye concentration led to higher K/S values,which were further augmented by mordanting,with aluminum potassium sulfate and stannous chloride yielding the greatest results.Colour fastness assessments indicated good to excellent resistance to washing,water exposure,rubbing,and perspiration,all of the properties were up to 4.Whereas resistance to light was found from 1 to 2.The findings confirm Cassia fistula extract as a renewable,eco-friendly dye for polyamide 6,offering commercially viable colour strength and fastness while supporting sustainable textile processing.
文摘In this paper,polyamide(PA)woven fabric was used as the base fabric,and polyurethane(PU)solution containing silica nanoparticles(PU@SiO_(2)NPs)was used as the coating solution to prepare composite tent fabric(PA/PU@SiO_(2)).The morphology,structure,and durability of the tent fabric under ultraviolet(UV)radiation,waterstained,or thermal conditions were investigated.The results show that compared with PA/PU fabric without SiO_(2)NPs,when the mass fraction of SiO_(2)NPs in PU coating is 5%,the air permeability of PA/PU@SiO_(2)fabric decreases from about 7.5 to 6.0 nm/s,while the reflectivity to UVvisible light is significantly improved.The surface wettability decreases,as indicated by the average water contact angle(WCA)on PA/PU@SiO_(2)remaining stable at 47°after 9 min.After thermal treatment,the PA/PU@SiO_(2)fabric shows superior mechanical stability.The degradation rate of the tensile strength is only 6.3%,approximately half that of the PA/PU fabric.Meanwhile,the elongation at break increases to 98.9%,compared to 61.8%for the PA/PU fabric.
基金supported by the National Natural Science Foundation of China (22138012)Shandong Energy Institute (SEI I202144,SEI I202133)。
文摘Lithium extraction from salt lakes has become an environmentally friendly way of lithium acquisition.The development of new nanofiltration membrane is significant to enhance the separation efficiency of lithium from a high Mg^(2+)/Li^(+) mass ratio brine.In this work,Fe^(3+)/tannic acid-trimesoyl chloride-polyetherimide(Fe^(3+)/TA-TMC-PEI) composite nanofiltration membranes were designed to study the separation performance of Mg^(2+)/Li^(+) in a high Mg^(2+)/Li^(+) mass ratio simulated brine.Fe^(3+)/TA separation layer was introduced through the rapid assembly of tannic acid and coordination mediated by Fe^(3+)on polyethersulfone supporting membrane.The polyamide layer was prepared through the reverse interfacial polymerization between TMC and PEI.The composite nanofiltration membrane has high crosslinking degree and positive charge and low pore size.The best performance of the composite nanofiltration membrane was obtained with 0.3%(mass) Fe^(3+) solution,0.9%(mass) TA,and 2 g·L^(-1) PEI 600ethanol solution.The retention of bivalent ions was significantly greater than that of monvalent ions in single salt solution.The Fe^(3+)/TA-TMC-PEI composite nanofiltration membrane showed a stable separation factor of 12.02 when the Mg^(2+)/Li^(+) mass ratio was 120 in the mixed salt solution.This work deepens the understanding of the mechanism of lithium extraction in magnesia-lithium system,and the modification strategy provides a possible guide for the design of Mg^(2+)/Li^(+) separation membranes with practical potential from the perspective of lithium extraction technology.
基金supported by the Fundamental Research Funds for the Central Universities(No.2023ZYGXZR107)the TCL Science and Technology Innovation Fund。
文摘Long-chain polyamides(LCPAs)are a class of bio-based polymers that can bridge conventional polyolefins and polycondensates.In this work,taking the advantage of the amphiphilic nature of polyamide 1012(PA1012),membranes were prepared by using a non-conventional phase separation approach,namely,mixed‘non-solvents’evaporation induced phase separation(MNEIPS).PA1012 can be dissolved in a mixture of polar and non-polar solvents,both of which are non-solvents of PA1012.During the sequential evaporation of the two solvents,the phase separation of PA1012 occurred,inducing the formation of porous structures.We investigated the process of membrane formation in detail,with a specific focus on the liquid-liquid and liquid-solid phase transitions involved.Moreover,we studied the influence of critical factors,such as polymer concentration and mixed-solvent ratio,on the morphologies and properties of PA1012 membranes.This study provides new insights into the development of porous materials based on long-chain polycondensates.
文摘Two master-batches,polyamide 66 (PA66)/organo-montmorillonite (OMMT) and polyamide 6 (PA6)/OMMT, prepared by melt compounding with methyl methacrylate (MMA) as co-intercalation agent,have been used to prepare nearly exfoliated PA661montmorillonite (MMT) nanocomposites.The resulting nanocomposites are compared in view of their morphology and properties.Nano-scale dispersion of OMMT is realized in both types of nanocomposites,as revealed by XRD,TEM and Molau tests.PA66/MMT nanocomposites having superior mecha...
文摘An improved method for preparing melamine cyanurate （MCA） based flame retardant polyamide 6 （FRPA6） materials has been proposed. This processing method, i.e., improved in situ polymerization, was used to synthesize flame retardant PA6. In situ formed MCA nanoparticles were supposed to be linked to PA6 chains in the ε-caprolactam hydrolytic polymerization system to obtain startype polymers for the first time. Through TEM photographs, it can be found that the in situ formed MCA nanoparticles with diametric size of less than 50 nm, are nanoscaled, highly uniformly dispersed in the PA6 matrix. Synthesized flame retardant PA6 have good fire performance which can achieve UL-94 V-0 rating at 1.6 mm thickness with the presence of 7.34 wt.% MCA in the matrix.
基金financially supported by the National Key Research and Development Program of China (Nos. 2017YFB0309301 and 2017YFB0309302)the Natural Science Foundation of Shanghai, China (No. 17ZR1407200)
文摘Novel bio-based and biodegradable block copolymers were synthesized by "click" reaction between poly(L-lactide)(PLLA) and polyamide 4(PA4). Upon tuning the molar mass of PLLA block, the properties of copolymers and electrospun ultrafine fibers were investigated and compared with those of PLLA and PA4 blends. PLLA and PA4 were found incompatible and formed individual crystalline regions, along with reciprocal inhibition in crystallization. Electrospun fibers were highly hydrophobic, even if hydrophilic PA4 was the rich component. The crystallinity of either PLLA or PA4 decreased after electrospinning and PLLA-rich as-spun fibers were almost amorphous. Immersion tests proved that fibers of block copolymers were relatively homogeneous with micro-phase separation between PLLA and PA4. The fibrous structures of copolymers were different from those of the fibers electrospun from blends, for which sheath-core structure induced by macro-phase separation between homopolymers of PLLA and PA4 was confirmed by TEM, EDS, and XPS.
文摘A diamine containing ether and ester units, as basic monomer for the preparation of polyamides, was prepared via three consecutive reactions. Nucleophilic substitution reaction of 1,4-dihydroxy benzene with 4-nitrobenzoyl chloride produced 4-hydroxyphenyl 4-nitrobenzoate （HPNB）. Reduction of nitro groups to amino groups using Fe and HC1 resulted in preparation of 4-hydroxyphenyl 4-aminobenzoate （HPAB）. The diamine was synthesized through nucleophilic substitution reaction of HPAB with 2,6-dichloropyridine. The precursors and diamine were fully characterized by common methods, and the diamine was polycondensed with different diacid chlorides in the presence of an acid scavenger to prepare new polyamides. The polyamides were characterized, and their physical properties including thermal stability and behavior, inherent viscosity and solubility were studied.
基金partially supported by the Grant-inAid for Scientific Research A(24241023)Grant-in-Aid for Challenging Exploratory Research(17K19139)from the Japan Society for the Promotion of Science
文摘Polyamide 6 underwent an efficient depolymerization in hydrophilic ionic liquids under microwave irradiation at 300C. The depolymerization completed within 60 min. Caprolactam was readily separated by simple extraction procedure and the ionic liquids were recovered and reused for several times. Addition of catalytic amounts of DMAP(N,N-dimethylaminopyridine) promoted the depolymerization effectively.The present improved procedure provides a method to avoid direct distillation procedure, which consumes energy for the separation of caprolactam from ionic liquids. Although some contamination of ionic liquids was observed, the present procedure provides a new possibility for the use of ionic liquids for plastic chemical recycling from the viewpoint of development of an energy-saving methodology. Use of solubility switchable ionic liquids is also examined to explore a possibility for better separation although depolymerization did not work well.
基金Supported by the National Natural Science Foundation of China.
文摘Liquid crystalline polymer-polyamide 66 (LCP/PA66) blends were compounded by using a Brabender mixing followed by compression moulding. The LCP employed was a semi-flexible liquid crystalline copolyesteramide based on 30% (molar fraction ) of p-amino benzoic acid (ABA ) and 70% (molar fraction) of poly (ethylene terephthalate) (PET). The LCP/PA66 blends were investigated in terms of the thermal and dynamic mechanical properties. It was found that PA66 and LCP components of the blends are miscible in the molten state, but are partially miscible in the solid state. The inclusion of the semi-flexible LCP into PA66 retards the crystallization rate of PA66. Furthermore, the melting temperature and the degree of crystallinity of PA66 are reduced considerably due to the LCP addition.
基金Supported by the National Natural Science Foundation of China （20676095）the Program of Introducing Talents of Discipline to Universities （B06006）
文摘Crosslinking treatments for a commercially available aromatic polyamide reverse osmosis membrane were carried out to improve its chlorine resistance.The crosslinking agents including 1,6-hexanediol diglycidyl ether,adipoyl dichloride and hexamethylene diisocyanate ester with long flexible aliphatic chains and high reactivity with N-H groups were used in the experiments.Attenuated total reflective Fourier transform infrared spectra verified the successful preparation of highly crosslinked membranes by crosslinking treatments.It was suggested that the crosslinking agents were connected to membrane surface through the reactions with amine and amide Ⅱ groups,which is confirmed by surface charge measurements.Based on contact angle measurements,crosslinking treatments decreased membrane hydrophilicity by introducing methylene groups to membrane surface.With increasing amount of crosslinking agent molecules connected to membrane surface,the hydrolysis of unconnected functional groups of crosslinking agent produced polar groups and increased membrane hydrophilicity.The highly crosslinked membranes showed higher salt rejections and lower water fluxes as compared with the raw membrane.Since the active sites(N-H groups) vulnerable to free chlorine on membrane surface were eliminated by crosslinking treatments,the chlorine resistances of the highly crosslinked membranes were significantly improved by slighter changes in both water fluxes and salt rejections after chlorination.
文摘Long chain semiaromatic polyamides with high molecular weight were synthesized by the reactions of undecanediamine with various aromatic diacids,and characterized by fourier transform infrared spectra（FT-IR） and nuclear magnetic resonance（1H-NMR）.The thermal behaviors were determined by differential scanning calorimetry（DSC） and thermogravimetric analysis（TGA）.The solubility,dynamic mechanical,physical and mechanical properties of the polyamides were also investigated.The experimental results show that the polyamides with high molecular weights are obtained only the PH value of the polyamides salt are in the range of 7.2-7.4.The melting temperatures and the glass transition temperatures of the polyamides increase with the increase of the rigidity of aromatic diacids,and are near to those of poly（nonamethylenetere-phthalamide）（PA9T）.
基金Thanks are kindly given to the Scientific and Technological Committee of Sichuan for financial supportWe are also grate-ful for project subsidizing by the Special Funds for Major Basic Research (Contract No. G1999064805) the National Natural Science
文摘In-situ composites based on dispersed poly (ethylene terephthalate) (PET) or polyamide (PA), and continuous polyethylene (PE) were prepared through a single screw extruder of Haake rheometer system with a rod-die relatively small in diameter. The extrudate was drawn at a drawing ratio of 3.1, and then quickly cooled in cold water. The specimens were obtained by injection molding at processing temperatures less than 190℃, far below the melting temperature of PET (265℃) and PA (230℃), which can maintain the solid state of PET and PA microfiber phase in the composites. Morphological observation with scanning electron microscopy (SEM) indicated that PET and PA can more or less form in-situ microfibers at compositions studied (0~20 wt pct PET or PA), and especially, PET and PA were almost deformed into fibers at the concentration of 15 wt pct. Tensile strength and modulus of the blends reinforced by PET or PA microfibers showed to be increased from the tensile test results. The most noticeable improvement of the tensile properties occurred at 15 wt pct of PET in PET/PE system, corresponding to the highest microfiber content, where the tensile strength reached 32.5 MPa, whereas only 19.5 MPa for the pure PE.
基金We would like to express our heartfelt thanks to the China National Distinguished Young Investigator Fund(No. 29925413) and the National Natural Science Foundation of China (No. 20274028) for Financial Support.
文摘Polyamide 11 (PA 11) is a widely used polyamide resin, but its application is limited since the impact properties, tensile strength, and thermal properties are not very satisfactory for industrial application. In order to improve the mechanical properties of PA 11, in this paper, the preparation of polyamide 11/clay nanocomposites (PACN) via in-situ intercalated polymerization was reported. SEM, TEM and XRD were employed to investigate the dispersion of clay sheet in the matrix. The results indicate that clay layers were homogeneously dispersed in PA11 matrix on a nano-scale, and an exfoliated and intercalated structure co-existed in the composites. The mechanical and thermal properties of the obtained nanocomposites were improved to certain extent by the addition of clay.
文摘A new hypocrellin B （HB） derivative bearing a bispyrrolecarboxamide-containing side chain was synthesized, which presents improved absorptivity in phototherapeufic window than HB and affinity feature towards dsDNA.
