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
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
A composite of nanocrystalline hydroxyapatite(n HA) and polyamide PA was prepared by the chemical methods of co precipitation and hydrothermal treatment. Hydrothermal treatment not only conduced to the formation of n ...A composite of nanocrystalline hydroxyapatite(n HA) and polyamide PA was prepared by the chemical methods of co precipitation and hydrothermal treatment. Hydrothermal treatment not only conduced to the formation of n HA but also enabled PA to be connected with n HA tightly. Using these methods, a dense composite powder containing high n HA /PA ratio (>50%) was obtained.展开更多
Hydroxyapatite nanoparticles(HAP NPs)were synthesized by a one‐step hydrothermal method.The surface of HAP NPs was grafted-SH and-COOH chelating groups via in situ surface‐modification with iminodiacetic acid(IDA)an...Hydroxyapatite nanoparticles(HAP NPs)were synthesized by a one‐step hydrothermal method.The surface of HAP NPs was grafted-SH and-COOH chelating groups via in situ surface‐modification with iminodiacetic acid(IDA)and 3‐mercaptopropyl trimethoxysilane(MPS)to afford dual surface‐capped nano‐amendment HAPIDA/MPS.The structure of HAP‐IDA/MPS was characterized,and its adsorption performance for Hg^(2+),Cu^(2+),Zn^(2+),Ni^(2+),Co^(2+),and Cd^(2+)was evaluated.The total adsorption capacity of 0.10 g HAP‐IDA/MPS nano‐amendment for Hg^(2+),Cu^(2+),Zn^(2+),Ni^(2+),Co^(2+),and Cd^(2+)with an initial mass concentration of 20 mg·L^(-1) reached 13.7 mg·g^(-1),about 4.3 times as much as that of HAP.Notably,HAP‐IDA/MPS nano‐amendment displayed the highest immobilization rate for Hg^(2+),possibly because of its chemical reaction with-SH to form sulfide,possessing the lowest solubility product constant among a variety of metal sulfides.展开更多
Hydroxyapatite (HA) is widely explored as a biocompatible filler to enhance the mechanical and functional properties of glass ionomer cements (GICs). HA of particle sizes 15 µm and 30 µm were added as a fill...Hydroxyapatite (HA) is widely explored as a biocompatible filler to enhance the mechanical and functional properties of glass ionomer cements (GICs). HA of particle sizes 15 µm and 30 µm were added as a filler into a matrix, composed of calcium aluminosilicate GICs and Poly-acrylic acid (PAA) in varying ratios. The tested ratios were Glass:PAA = 2:1 and Glass:HA:PAA = 2:0.5:1 to improve the mechanical strength of a conventional GIC. Mechanical properties, including compressive, flexural, and diametral tensile strength were studied at different setting times. The compressive strength (CS) was improved with hydroxyapatite addition and prolonged setting time while diametral tensile strength (DTS) did not follow any specific trend. The flexural strength (FS) of the composite cement was increased with increasing setting time regardless of the particle size of hydroxyapatite. The FTIR spectra of hydroxyapatite of particle sizes 15 μm and 30 μm are similar but for HA-GIC composites, the FTIR spectra, the peak around 1460 cm−1 are due to C-H and the peak at 1553 cm−1 is due to calcium carboxylate with calcium in a bridging mode which would be an excellent material that chemically bonds to the tooth structure, making it effective for both restorative procedures and cavity fillings. Scanning electron microscopy (SEM) microstructural study revealed that the glass particles were wrenched out, which was a cohesive fracture. The X-ray diffraction (XRD) pattern showed that the hydroxyapatite has a crystalline single-phase, hexagonal structure. The sharp peaks between the 2-theta range of 30 - 40 degrees are the same as in enamel powder. The spectra indicate the pure set cement as amorphous since there is no prominent peak, but with the addition of hydroxyapatite filler, the peak in the 2-theta range of 20 - 35 degrees is ascribed to crystalline apatite structure. The results indicate that incorporating hydroxyapatite into GIC significantly enhances its mechanical properties and structural integrity, suggesting its potential as an improved material for dental and restorative applications.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
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
Biodegradable magnesium(Mg)alloys have received increased attention as temporary medical implants due to their mechanical properties and density,similar to natural bone.However,the fast corrosion of Mg alloys in a phy...Biodegradable magnesium(Mg)alloys have received increased attention as temporary medical implants due to their mechanical properties and density,similar to natural bone.However,the fast corrosion of Mg alloys in a physiological condition limits their wide applications.Hence,hydroxyapatite(HAp)coatings on Mg alloys have attracted much attention to address this corrosion issue and enhance the surface functionalities.In this paper,we present a review of HAp coating strategies on Mg alloys,including the sol-gel method,hydrothermal treatment,biomimetic coating,electrochemical deposition,electrophoretic deposition,and plasma electrolytic oxidation technique,and their recent progress to enhance the surface characteristics of Mg alloys.This review focused on aspects of coating morphology,hybrid formulations,and how they influence corrosion behavior as well as in vitro and in vivo performance.Moreover,we have discussed the future prospects of HAp-coating strategies,emphasizing on multifunctional,hybrid,and smart coatings for next-generation implant materials.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
The field of bone tissue engineering has experienced an increase in prevalence due to the inherent challenge of the natural regeneration of significant bone deformities.This investigation focused on the preparation of...The field of bone tissue engineering has experienced an increase in prevalence due to the inherent challenge of the natural regeneration of significant bone deformities.This investigation focused on the preparation of Three-Dimensional(3D)-printed Polycaprolactone(PCL)scaffolds with varying proportions of Nanohydroxyapatite(NHA)and Nanoclay(NC),and their physiochemical and biological properties were assessed.The mechanical properties of PCL are satisfactory;however,its hydrophobic nature and long-term degradation hinder its use in scaffold fabrication.NHA and NC have been employed to improve the hydrophilic characteristics,mechanical strength,adhesive properties,biocompatibility,biodegradability,and osteoconductive behavior of PCL.The morphology results demonstrated 3D-printed structures with interconnected rectangular macropores and proper nanoparticle distribution.The sample containing 70 wt%NC showed the highest porosity(65.98±2.54%),leading to an increased degradation rate.The compressive strength ranged from 10.65±1.90 to 84.93±9.93 MPa,which is directly proportional to the compressive strength of cancellous bone(2–12 MPa).The wettability,water uptake,and biodegradability of PCL scaffolds considerably improved as the amount of NC increased.The results of the cellular assays exhibited increased proliferation,viability,and adhesion of MG-63 cells due to the addition of NHA and NC to the scaffolds.Finally,according to the in vitro results,it can be concluded that 3D-printed samples with higher amounts of NC can be regarded as a suitable scaffold for expediting the regeneration process of bone defects.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
Tissue engineering holds promise in developing materials for biological applications,such as bone tissue repair.This study focuses on bioabsorbable and biocompatible polymers like Poly(L-lactic acid)(PLLA),Polyurethan...Tissue engineering holds promise in developing materials for biological applications,such as bone tissue repair.This study focuses on bioabsorbable and biocompatible polymers like Poly(L-lactic acid)(PLLA),Polyurethane(PU),and Polycaprolactone(PCL),along with nanohydroxyapatite(nHA),an essential osteoconductive ceramic.The main objective was the development and characterization of scaffolds obtained by Rotary Jet Spinning(RJS)using PLLA,PU,and PCL incorporated with nHA,for bone-related applications.The resulting scaffolds exhibited uniform fiber morphology and a rough surface,ideal for effective bone-tissue interaction.The crystallinity indicated the scaffolds’bioactivity by apatite deposition in simulated body fluid.In addition,in vitro biological assays using preosteoblastic cells showed the biocompatibility of cells based on cell viability and adhesion parameters on the scaffolds.The results underscore the capacity of scaffolds incorporating nHA to promote both cell proliferation and osteoconduction,which are key elements essential for achieving effective bone regeneration.展开更多
The mesoporous hydroxyapatite （HA） was synthesized by hydrothermal method utilizing cationic surfactant cetyltrimethylammonium bromide （CTAB） as template. The crystalline phase, morphology and porous structure wer...The mesoporous hydroxyapatite （HA） was synthesized by hydrothermal method utilizing cationic surfactant cetyltrimethylammonium bromide （CTAB） as template. The crystalline phase, morphology and porous structure were characterized respectively by different detecting techniques. The results reveal that the particles are highly crystalline hydroxyapatite phase. The surfactant has little influence on the morphology of the crystals, but affects the porous structure obviously. The sample without CTAB has a low surface area not exceeding 33 m^2/g, and no distinct pores can be observed by TEM. While the samples obtained with the surfactant get better parameters. Numerous open-ended pores centered at 2-7 nm spread unequally on the surface of the hydroxyapatite nanorods. The N2 adsorption-desorption experiments show type IV isotherms with distinct hysteresis loops, illustrating the presence of mesoporous structure. When the mole ratio of CTAB to HA is 1：2, the sample has the largest surface area of 97.1 m^2/g and pore volume of 0.466 cm^3/g.展开更多
In order to further improve the transfection efficiency of hydroxyapatite nanoparticle （HAp）, arginine functionalized hydroxyapatite （HAp/Arg） was synthesized by hydrothermal synthesis. The morphology, crystallite...In order to further improve the transfection efficiency of hydroxyapatite nanoparticle （HAp）, arginine functionalized hydroxyapatite （HAp/Arg） was synthesized by hydrothermal synthesis. The morphology, crystallite size and zeta potential of the HAp/Arg were characterized by transmission electron microscopy （TEM）, atomic force microscopy （AFM） and zeta potential analyzer. The loading and protecting properties of HAp/Arg to DNA were tested by electrophoresis. Its cytotoxicity was also measured in Hela cells and HAEC cells by MTT and LDH, and its transfection efficiency was examined by fluorescence microscope and flow cytometry. The results reveal that HAp/Arg is short rod-like and nano single crystal, the mean diameter is 50-90 nm and zeta potential is 35.8 mV at pH 7.4. HAp/Arg to DNA can be condensed by electrostatic effect and protect DNA against degradation in DNase I, and shows high transfection efficiency without cytotoxicity. These results suggest that HAp/Arg can be a promising alternative as a novel gene delivery system.展开更多
The mixture of CaHPO 4·2H 2O and CaCO 3 was ground in an aqueous system under appropriate conditions to investigate the mechanochemical reaction for the synthesis of crystalline hydroxyapatite (HA) powder. Hyd...The mixture of CaHPO 4·2H 2O and CaCO 3 was ground in an aqueous system under appropriate conditions to investigate the mechanochemical reaction for the synthesis of crystalline hydroxyapatite (HA) powder. Hydroxyapatite of high crystallinity powder including trace Ca 10 (PO 4) 6CO 3(OH) and Ca 9HPO 4(PO 4) 6OH can be synthesized by mechanical activation without further thermal treatment at a high temperature. The synthesis reaction during the grinding process was almost completed within 1h. The as-ground powder exhibits a particle distribution of 20-100nm in size with a spherical or rodlike morphology. The composition and degree of crystallinity of the mechanochemical synthesized hydroxyapatite powders were coincident with the cement-type hydroxyapatite.展开更多
The arginine-modified and europium-doped hydroxyapatite nanoparticles（HAP-Eu） were synthesized by hydrothermal synthesis.The prepared nanoparticles were characterized by transmission electron microscopy（TEM）,X-ray...The arginine-modified and europium-doped hydroxyapatite nanoparticles（HAP-Eu） were synthesized by hydrothermal synthesis.The prepared nanoparticles were characterized by transmission electron microscopy（TEM）,X-ray diffractometry（XRD）,Fourier transform infrared（FTIR） and zeta potential analyzer.The cell viability of HAP-Eu was tested by image flow cytometry.The results indicated that HAP-Eu is short column shapes and its size is approximately 100 nm,its zeta potential is about 30.10 mV at pH of 7.5,and shows no cytotoxicity in human epithelial cells and endothelial cells.展开更多
Objective:To investigate possible effects of nanophase powder of hydroxyapatite on proliferation of periodontal ligament cells. Methods: With sol-gel method, the nanophase hydroxyapatite powders were fabricated. These...Objective:To investigate possible effects of nanophase powder of hydroxyapatite on proliferation of periodontal ligament cells. Methods: With sol-gel method, the nanophase hydroxyapatite powders were fabricated. These powders were proved nanopaticles by transmission electron microscope. The effects on proliferation of periodontal ligament cell(PDLC) were observed in vitro with MTT [3-(4,5dimethylthiazo;-2-yl)-2,5-diphenytetralium bromide] method. Results: On the 2nd,3rd,4th day after treated with nanoparticles of hydroxyapatite, the proliferate activity of the PDLC increases significantly, compared with those with dense hydroxyaoatite and control but no significant difference could be found between the dense hydroxyapatite and the control. Conclusion: Nanophase hydroxyapatite can promote the regeneration of periodontal tissue.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
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.
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A composite of nanocrystalline hydroxyapatite(n HA) and polyamide PA was prepared by the chemical methods of co precipitation and hydrothermal treatment. Hydrothermal treatment not only conduced to the formation of n HA but also enabled PA to be connected with n HA tightly. Using these methods, a dense composite powder containing high n HA /PA ratio (>50%) was obtained.
文摘Hydroxyapatite nanoparticles(HAP NPs)were synthesized by a one‐step hydrothermal method.The surface of HAP NPs was grafted-SH and-COOH chelating groups via in situ surface‐modification with iminodiacetic acid(IDA)and 3‐mercaptopropyl trimethoxysilane(MPS)to afford dual surface‐capped nano‐amendment HAPIDA/MPS.The structure of HAP‐IDA/MPS was characterized,and its adsorption performance for Hg^(2+),Cu^(2+),Zn^(2+),Ni^(2+),Co^(2+),and Cd^(2+)was evaluated.The total adsorption capacity of 0.10 g HAP‐IDA/MPS nano‐amendment for Hg^(2+),Cu^(2+),Zn^(2+),Ni^(2+),Co^(2+),and Cd^(2+)with an initial mass concentration of 20 mg·L^(-1) reached 13.7 mg·g^(-1),about 4.3 times as much as that of HAP.Notably,HAP‐IDA/MPS nano‐amendment displayed the highest immobilization rate for Hg^(2+),possibly because of its chemical reaction with-SH to form sulfide,possessing the lowest solubility product constant among a variety of metal sulfides.
文摘Hydroxyapatite (HA) is widely explored as a biocompatible filler to enhance the mechanical and functional properties of glass ionomer cements (GICs). HA of particle sizes 15 µm and 30 µm were added as a filler into a matrix, composed of calcium aluminosilicate GICs and Poly-acrylic acid (PAA) in varying ratios. The tested ratios were Glass:PAA = 2:1 and Glass:HA:PAA = 2:0.5:1 to improve the mechanical strength of a conventional GIC. Mechanical properties, including compressive, flexural, and diametral tensile strength were studied at different setting times. The compressive strength (CS) was improved with hydroxyapatite addition and prolonged setting time while diametral tensile strength (DTS) did not follow any specific trend. The flexural strength (FS) of the composite cement was increased with increasing setting time regardless of the particle size of hydroxyapatite. The FTIR spectra of hydroxyapatite of particle sizes 15 μm and 30 μm are similar but for HA-GIC composites, the FTIR spectra, the peak around 1460 cm−1 are due to C-H and the peak at 1553 cm−1 is due to calcium carboxylate with calcium in a bridging mode which would be an excellent material that chemically bonds to the tooth structure, making it effective for both restorative procedures and cavity fillings. Scanning electron microscopy (SEM) microstructural study revealed that the glass particles were wrenched out, which was a cohesive fracture. The X-ray diffraction (XRD) pattern showed that the hydroxyapatite has a crystalline single-phase, hexagonal structure. The sharp peaks between the 2-theta range of 30 - 40 degrees are the same as in enamel powder. The spectra indicate the pure set cement as amorphous since there is no prominent peak, but with the addition of hydroxyapatite filler, the peak in the 2-theta range of 20 - 35 degrees is ascribed to crystalline apatite structure. The results indicate that incorporating hydroxyapatite into GIC significantly enhances its mechanical properties and structural integrity, suggesting its potential as an improved material for dental and restorative applications.
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the Deanship of Research and Graduate Studies at King Khalid University for funding this work through Small Group Research Project under grant number RGP1/34/46 (RGP1/34/46)
文摘Biodegradable magnesium(Mg)alloys have received increased attention as temporary medical implants due to their mechanical properties and density,similar to natural bone.However,the fast corrosion of Mg alloys in a physiological condition limits their wide applications.Hence,hydroxyapatite(HAp)coatings on Mg alloys have attracted much attention to address this corrosion issue and enhance the surface functionalities.In this paper,we present a review of HAp coating strategies on Mg alloys,including the sol-gel method,hydrothermal treatment,biomimetic coating,electrochemical deposition,electrophoretic deposition,and plasma electrolytic oxidation technique,and their recent progress to enhance the surface characteristics of Mg alloys.This review focused on aspects of coating morphology,hybrid formulations,and how they influence corrosion behavior as well as in vitro and in vivo performance.Moreover,we have discussed the future prospects of HAp-coating strategies,emphasizing on multifunctional,hybrid,and smart coatings for next-generation implant materials.
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.
文摘The field of bone tissue engineering has experienced an increase in prevalence due to the inherent challenge of the natural regeneration of significant bone deformities.This investigation focused on the preparation of Three-Dimensional(3D)-printed Polycaprolactone(PCL)scaffolds with varying proportions of Nanohydroxyapatite(NHA)and Nanoclay(NC),and their physiochemical and biological properties were assessed.The mechanical properties of PCL are satisfactory;however,its hydrophobic nature and long-term degradation hinder its use in scaffold fabrication.NHA and NC have been employed to improve the hydrophilic characteristics,mechanical strength,adhesive properties,biocompatibility,biodegradability,and osteoconductive behavior of PCL.The morphology results demonstrated 3D-printed structures with interconnected rectangular macropores and proper nanoparticle distribution.The sample containing 70 wt%NC showed the highest porosity(65.98±2.54%),leading to an increased degradation rate.The compressive strength ranged from 10.65±1.90 to 84.93±9.93 MPa,which is directly proportional to the compressive strength of cancellous bone(2–12 MPa).The wettability,water uptake,and biodegradability of PCL scaffolds considerably improved as the amount of NC increased.The results of the cellular assays exhibited increased proliferation,viability,and adhesion of MG-63 cells due to the addition of NHA and NC to the scaffolds.Finally,according to the in vitro results,it can be concluded that 3D-printed samples with higher amounts of NC can be regarded as a suitable scaffold for expediting the regeneration process of bone defects.
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financial support from FAPESP-Sao Paulo Research Foundation[grants #2020/07923-0,and #2023/11076-0]the National Council for Scientific and Technological Development-CNPq[grant #406514/2021-6].
文摘Tissue engineering holds promise in developing materials for biological applications,such as bone tissue repair.This study focuses on bioabsorbable and biocompatible polymers like Poly(L-lactic acid)(PLLA),Polyurethane(PU),and Polycaprolactone(PCL),along with nanohydroxyapatite(nHA),an essential osteoconductive ceramic.The main objective was the development and characterization of scaffolds obtained by Rotary Jet Spinning(RJS)using PLLA,PU,and PCL incorporated with nHA,for bone-related applications.The resulting scaffolds exhibited uniform fiber morphology and a rough surface,ideal for effective bone-tissue interaction.The crystallinity indicated the scaffolds’bioactivity by apatite deposition in simulated body fluid.In addition,in vitro biological assays using preosteoblastic cells showed the biocompatibility of cells based on cell viability and adhesion parameters on the scaffolds.The results underscore the capacity of scaffolds incorporating nHA to promote both cell proliferation and osteoconduction,which are key elements essential for achieving effective bone regeneration.
基金Projects(51102285,81170912)supported by the National Natural Science Foundation of ChinaProject supported by the Open Foundation of State Key Laboratory of Powder Metallurgy,China
文摘The mesoporous hydroxyapatite （HA） was synthesized by hydrothermal method utilizing cationic surfactant cetyltrimethylammonium bromide （CTAB） as template. The crystalline phase, morphology and porous structure were characterized respectively by different detecting techniques. The results reveal that the particles are highly crystalline hydroxyapatite phase. The surfactant has little influence on the morphology of the crystals, but affects the porous structure obviously. The sample without CTAB has a low surface area not exceeding 33 m^2/g, and no distinct pores can be observed by TEM. While the samples obtained with the surfactant get better parameters. Numerous open-ended pores centered at 2-7 nm spread unequally on the surface of the hydroxyapatite nanorods. The N2 adsorption-desorption experiments show type IV isotherms with distinct hysteresis loops, illustrating the presence of mesoporous structure. When the mole ratio of CTAB to HA is 1：2, the sample has the largest surface area of 97.1 m^2/g and pore volume of 0.466 cm^3/g.
基金Project(2013SK2024)supported by the Key Projects in Social Development Pillar Program of Hunan Province,ChinaProject(20130162120094)supported by Specialized Research Fund for the Doctoral Program of Higher Education(SRFDP),Ministry of Education,ChinaProjects(81071869,51305464)supported by the National Natural Science Foundation of China
文摘In order to further improve the transfection efficiency of hydroxyapatite nanoparticle （HAp）, arginine functionalized hydroxyapatite （HAp/Arg） was synthesized by hydrothermal synthesis. The morphology, crystallite size and zeta potential of the HAp/Arg were characterized by transmission electron microscopy （TEM）, atomic force microscopy （AFM） and zeta potential analyzer. The loading and protecting properties of HAp/Arg to DNA were tested by electrophoresis. Its cytotoxicity was also measured in Hela cells and HAEC cells by MTT and LDH, and its transfection efficiency was examined by fluorescence microscope and flow cytometry. The results reveal that HAp/Arg is short rod-like and nano single crystal, the mean diameter is 50-90 nm and zeta potential is 35.8 mV at pH 7.4. HAp/Arg to DNA can be condensed by electrostatic effect and protect DNA against degradation in DNase I, and shows high transfection efficiency without cytotoxicity. These results suggest that HAp/Arg can be a promising alternative as a novel gene delivery system.
文摘The mixture of CaHPO 4·2H 2O and CaCO 3 was ground in an aqueous system under appropriate conditions to investigate the mechanochemical reaction for the synthesis of crystalline hydroxyapatite (HA) powder. Hydroxyapatite of high crystallinity powder including trace Ca 10 (PO 4) 6CO 3(OH) and Ca 9HPO 4(PO 4) 6OH can be synthesized by mechanical activation without further thermal treatment at a high temperature. The synthesis reaction during the grinding process was almost completed within 1h. The as-ground powder exhibits a particle distribution of 20-100nm in size with a spherical or rodlike morphology. The composition and degree of crystallinity of the mechanochemical synthesized hydroxyapatite powders were coincident with the cement-type hydroxyapatite.
基金Project (81071869) supported by the National Natural Science Foundation of China Project (2009637526) supported by China Scholarship Council (CSC Program)Project (2010QZZD006) supported by the Key Program of Central South University Advancing Front Foundation
文摘The arginine-modified and europium-doped hydroxyapatite nanoparticles（HAP-Eu） were synthesized by hydrothermal synthesis.The prepared nanoparticles were characterized by transmission electron microscopy（TEM）,X-ray diffractometry（XRD）,Fourier transform infrared（FTIR） and zeta potential analyzer.The cell viability of HAP-Eu was tested by image flow cytometry.The results indicated that HAP-Eu is short column shapes and its size is approximately 100 nm,its zeta potential is about 30.10 mV at pH of 7.5,and shows no cytotoxicity in human epithelial cells and endothelial cells.
文摘Objective:To investigate possible effects of nanophase powder of hydroxyapatite on proliferation of periodontal ligament cells. Methods: With sol-gel method, the nanophase hydroxyapatite powders were fabricated. These powders were proved nanopaticles by transmission electron microscope. The effects on proliferation of periodontal ligament cell(PDLC) were observed in vitro with MTT [3-(4,5dimethylthiazo;-2-yl)-2,5-diphenytetralium bromide] method. Results: On the 2nd,3rd,4th day after treated with nanoparticles of hydroxyapatite, the proliferate activity of the PDLC increases significantly, compared with those with dense hydroxyaoatite and control but no significant difference could be found between the dense hydroxyapatite and the control. Conclusion: Nanophase hydroxyapatite can promote the regeneration of periodontal tissue.
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.
