A visible-light-enabled method for the synthesis ofα-azidoketones has been developed via oxo-azidation of alkenyl silanes with trimethylsilylazide and molecular oxygen under mild conditions.The reaction could be carr...A visible-light-enabled method for the synthesis ofα-azidoketones has been developed via oxo-azidation of alkenyl silanes with trimethylsilylazide and molecular oxygen under mild conditions.The reaction could be carried out in gram scale.Various radical sources,including trifluoromethyl radical,thiocyanate radical,bromide radical,chlorine radical could partici-pate effectively instead of azide radical in the reaction.展开更多
The incorporation of KH560-modified steel slag(MSS)as a filler in alkyd coatings significantly impacts their corrosion resistance and mechanical properties.The modification process was characterized using the Fourier ...The incorporation of KH560-modified steel slag(MSS)as a filler in alkyd coatings significantly impacts their corrosion resistance and mechanical properties.The modification process was characterized using the Fourier transform infrared spectrometer,scanning electron microscope,and X-ray photoelectron spectroscope to understand the chemical and morphological changes induced by KH560 treatment.Three types of coatings were prepared:pure alkyd coating(AC),steel slag/alkyd coating(SS/AC),and KH560-modified steel slag/alkyd coating(MSS/AC).Their corrosion resistance was evaluated by electrochemical impedance spectroscopy and salt spray tests,while mechanical properties such as hardness,adhesion,and flexibility were also assessed.Results show that MSS significantly enhances the hardness,flexibility,and adhesion of the coatings,forming a composite structure(MSS-KH560-alkyd)that significantly improves the performance of MSS/AC.Notably,MSS/AC demonstrated superior hydrophobicity with a water absorption rate of 0.624%and a contact angle of 100.7°.Electrochemical tests revealed an impedance modulus of 3.9×10^(7)Ωcm^(2),a corrosion current of 3.39×10^(−4)mA,and a corrosion potential of−35 mV for MSS/AC.After a 10-d immersion in a 3.5 wt.%NaCl solution,MSS/AC maintained its protective properties.These findings underscore the potential of MSS as a sustainable and effective filler for alkyd coatings in corrosion protection applications.展开更多
Magnesium alloys hold promise as biodegradable orthopedic implants but suffer from rapid corrosion and poor corrosion fatigue performance.This study evaluates the efficacy of a micro-arc oxidation(MAO)layer combined w...Magnesium alloys hold promise as biodegradable orthopedic implants but suffer from rapid corrosion and poor corrosion fatigue performance.This study evaluates the efficacy of a micro-arc oxidation(MAO)layer combined with 3-glycidyloxypropyltrimethoxysilane(GPTMS)sealing in enhancing the corrosion fatigue behavior of ZE21B magnesium alloy in Hanks’Balanced Salt Solution(HBSS).Electrochemical testing revealed a two-order-of-magnitude reduction in corrosion current density compared to bare alloy,while immersion tests demonstrated sustained protection against degradation.Corrosion fatigue experiments under cyclic loading showed stress-dependent performance:the composite coating improved fatigue life at low stress amplitudes(60 MPa)by mitigating corrosion pit formation,but interfacial weakness between GPTMS and MAO layers reduced performance at high stresses(90-80 MPa).Fractographic analysis identified asynchronous deformation and stress gradient-dependent coating spallation as key failure modes.These results provide mechanistic insights into coating degradation pathways and offer design strategies for developing robust surface modification systems to advance magnesium-based orthopedic applications.展开更多
With the rapid development of flexible wearable electronic products,their application fields and demands are increasing,posing new challenges to flexible conductive materials.This paper selected flexible polydimethyls...With the rapid development of flexible wearable electronic products,their application fields and demands are increasing,posing new challenges to flexible conductive materials.This paper selected flexible polydimethylsiloxane(PDMS)as the substrate.In order to enhance the adhesion between the substrate and the metal coating,dopamine and silanization were used to co-modify its surface.A conductive layer of metallic copper is deposited on its surface using an inexpensive,easy-to-use electroless plating technique.By optimizing the process conditions,it is found that a uniform copper layer of about 0.6μm can be formed on the surface of the substrate by electroless plating at a constant temperature of 45℃ for 30 min with a conductivity of 5556 S/cm.The relative resistance changes under different deformation conditions,and the I-V curve of the LED circuit is not very different.Therefore,this paper prepared a flexible conductor with excellent electrical conductivity,high coating adhesion,and good electrical stability under large-scale deformation.展开更多
An environmentally friendly waterborne polyurethane(CWPU)emulsion was developed via a dual modification strategy by combining both the silane coupling agent KH-602 with renewable castor oil(CO)as a sustainable substit...An environmentally friendly waterborne polyurethane(CWPU)emulsion was developed via a dual modification strategy by combining both the silane coupling agent KH-602 with renewable castor oil(CO)as a sustainable substitute for petroleum-based polyols.The resulting materials were thoroughly characterized using Fourier-transform infrared spectroscopy(FTIR),thermogravimetric analysis(TGA),and differential scanning calorimetry(DSC).Furthermore,the influence of KH-602 content on the material properties was systematically investigated.The experimental results reveal that the incorporation of KH-602 significantly improves the thermal stability of the composite coating.As the KH-602 content increases,the tensile strength exhibits a gradual enhancement,while the elongation at break displays an initial increase followed by a subsequent decline.At an optimal KH-602 content of 3%,the coating demonstrates a balanced performance,achieving a tensile strength of 14.19 MPa and an elongation at break of 731.12%.These results suggest that the dual modification approach enhances mechanical and thermal properties while maintaining water resistance,making it suitable for sustainable coating applications.展开更多
The new energy vehicle body composed of multi-metals requires a synchronous chemical conversion coating to exhibit excellent corrosion resistance.Herein,we prepared a titanium/zirconium/water-based oligomeric epoxy si...The new energy vehicle body composed of multi-metals requires a synchronous chemical conversion coating to exhibit excellent corrosion resistance.Herein,we prepared a titanium/zirconium/water-based oligomeric epoxy silane composite chemical conversion coating on multi-metals,and conducted an investigation into its electrochemical behavior and micro-zone structural characteristics upon immersion in a 3.5%NaCl solution.The electrochemical results combined with characterization results revealed that the corrosion evolution characteristics of the composite coatings could be categorized into three stages of mild corrosion,synergistic protection,and substrate damage.Besides,Si-OH groups interact with Me-OH at the defect on the multi-metal surface to form an organic monolayer coating.This organic monolayer coating,in conjunction with the synergistic inorganic conversion layer comprising Al_(2)O_(3),TiO_(2),2H_(2)O,ZrO_(2),2H_(2)O,effectively cooperates with the corrosion products to hinder the erosion by the corrosive medium and suppresses the progression of the anodic reaction.展开更多
The direct conversion of methane into aromatics under non-oxidative conditions has received considerable attention since 1993^[1-3].Mo/HZSM-5 is the best one among the tested catalysts.It is generally accepted that th...The direct conversion of methane into aromatics under non-oxidative conditions has received considerable attention since 1993^[1-3].Mo/HZSM-5 is the best one among the tested catalysts.It is generally accepted that the activation of the C-H bond of methane and initial C-C bond formation occur on Mocarbides formed from the reduction of Mo O,species,while the further transformation of C^(2+)hydrocarbons occurs on the Bronsted acid sites of HZSM-5 zeolite^[4].The unique channel structure of HZSM-5 plays a crucial role in constraining side reactions and controlling the product distribution^[5].The Bronsted acid sites of HZSM-5 are also responsible for the for-mation of carbonaceous deposits[6].展开更多
Aim To determine the effect of silane grafted polypropylene on the property of different filler/polypropylene composites. Methods Polypropylene (PP) composites filled with talc(Ta), baryta sulfate and calcium carbonat...Aim To determine the effect of silane grafted polypropylene on the property of different filler/polypropylene composites. Methods Polypropylene (PP) composites filled with talc(Ta), baryta sulfate and calcium carbonate coupled with silane grafted polypropylene (PP-g-Si) were made, their mechanical properties and thermal properties were investigated, respectively. Results As compared with the non-coupled composites, the mechanical properties of PP/Ta/PP-g-Si composites were improved to some extent, though the values of tensile modulus and the strain at peak were decreased. But for PP/BaSO4 and PP/CaCO3 composites, the values of their mechanical properties varied slightly or even decreased with increasing PP-g-Si content within the experimental component. Meanwhile, PP-g-Si also affected the melting and crystallization behavior of PP in the composites. Conclusion PP-g-Si offers compatibilization in PP/Ta composites, but offers no-compatibilization in PP/BaSO4 and PP/CaCO3 composites within the extent of the present range of PP-g-Si, which shows that PP-g-Si can be used as the macromolecular coupling agent of PP and Ta composite.展开更多
Novel hollow Fe3O4 nanoparticles for drug delivery were synthesized via a one-step template- free approach. These nanoparticles were obtained by modifing the Fe3O4 nanoparticles with 3-aminopropyltrimethoxy silane, an...Novel hollow Fe3O4 nanoparticles for drug delivery were synthesized via a one-step template- free approach. These nanoparticles were obtained by modifing the Fe3O4 nanoparticles with 3-aminopropyltrimethoxy silane, and then grafting alginate onto the surface of amine magnetic. The hollow structure of Fe3O4 spheres was characterized by TEM, XRD, and XPS. The M-H hysteresis loop indicated that the magnetic spheres exhibit snperparamagnetic characteristics at room temperature. Daunorubicin acting as a model drug was loaded into the carrier, and the maximum percent of envelop and load were 28.4% and 14.2% respectively. The drug controlled releasing behaviors of the carriers were compared in different pH media.展开更多
The present work aimed at using rare earth lanthanum salt and trimethoxy（viny）silance as chromate substitutes for galvanized steel passivation, in contrast to zinc coating samples treated with chromate.The corrosion...The present work aimed at using rare earth lanthanum salt and trimethoxy（viny）silance as chromate substitutes for galvanized steel passivation, in contrast to zinc coating samples treated with chromate.The corrosion resistance was assessed by electrochemical impedance spectroscopy（EIS） and neutral salt spray tests（NSS）.Scanning electron microscopy（SEM） was used to characterize the sample surfaces.The organic coating adhesion on the panel was also investigated via varnishes-cross cut tests.The results indicated that rare earth and silane two-step treatment gave more effective anticorrosion performance than Cr, which also provided good paint adhesion.The coating formation mechanism was also discussed.展开更多
Bis-3-(triethoxysilyl)propyltetrasulfide(BTESPT) silane-rare earth cerium composite coatings on aluminum-tube were prepared at 60 °C by immersion method.The performance of composite coatings to protect the alumin...Bis-3-(triethoxysilyl)propyltetrasulfide(BTESPT) silane-rare earth cerium composite coatings on aluminum-tube were prepared at 60 °C by immersion method.The performance of composite coatings to protect the aluminum-tube against corrosion was investigated with potentiodynamic polarization curves,electrochemical impedance spectroscopy(EIS),and salt spray test(SST).The results of potentiodynamic polarization curves and EIS indicated that the self-corrosion current decreased by two orders of magnitude and the i...展开更多
A complex film on hot-dip galvanized steel sheet（HDG） was prepared by immersing the sheet in 0.1wt.% Ce（NO3）3 solution and 5vol.% silane solution in turn.The corrosion protection of the complex film was evaluated ...A complex film on hot-dip galvanized steel sheet（HDG） was prepared by immersing the sheet in 0.1wt.% Ce（NO3）3 solution and 5vol.% silane solution in turn.The corrosion protection of the complex film was evaluated by potentiodynamic linear polarization（LPR）, electrochemical impendence spectra（EIS） and natural salt spray（NSS） tests and compared with that of single cerium film and silane film.The results showed that, the presence of these films on the zinc coating hindered corrosion reaction by reducing the rate of both anodic and cathodic reaction in the corrosion process, and the corrosion protection of the complex film was much better than that of single cerium film or silane film and closed to that of chromate film, because the polarization resistance Rp and electrochemical impendence were increased markedly.Microstructure and chemical composition of these pretreated films were also investigated by scanning electron microscopy（SEM） and AES.展开更多
A novel waterborne epoxy curing agent was prepared using 3-glycidoxypropyl trimethoxysilane （GPTMS） as a termination agent of adduct, which was synthesized by triethylene tetramine （TETA） and liquid epoxy resin （...A novel waterborne epoxy curing agent was prepared using 3-glycidoxypropyl trimethoxysilane （GPTMS） as a termination agent of adduct, which was synthesized by triethylene tetramine （TETA） and liquid epoxy resin （E-51）. The effects of the reaction temperature and time on the synthesis process were investigated experimentally. The particle size and the distribution of water dispersion of the curing agent were measured by dynamic light scattering（DLS）. The structure of the products was characterized by Fourier transform infrared spec-trometer （FTIR） and ^1H-nuclear magnetic resonance （^1H NMR）. The properties of the synthesized curing agent and the epoxy resin film cured by it were also measured. The results showed that the appropriate temperature for the synthesis of adduct was at 65-75℃ and the reaction time was 4-5h, and that the suitable reaction temperature of curing agent synthesis was 75-85℃ and the reaction time was 3-4h. When the mass ratios of GPTMS and acetic acid were 3%-5% and 5%-10% respectively, the hardness, water resistance and adhesion of the cured film were improved significantly.展开更多
Mg(OH)2/Mg-Al-layered double hydroxide (LDH) coatings were modified with methyltrimethoxysilane (MTMS) on magnesium alloys. Effect of hydrolysis degree of silane solution on coating formation was investigated. Chemica...Mg(OH)2/Mg-Al-layered double hydroxide (LDH) coatings were modified with methyltrimethoxysilane (MTMS) on magnesium alloys. Effect of hydrolysis degree of silane solution on coating formation was investigated. Chemical compositions and surface morphologies of the coatings were examined using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and field-emission scanning electronic microscopy (FESEM). Results indicated that the composite coatings consisted of polymethyltrimethoxysilane (PMTMS), LDH and Mg(OH)2. Electrochemical and hydrogen evolution measurements revealed that the composite coatings possessed good corrosion resistance, especially the ones prepared in a high hydrolysis degree of silane. The optimum corrosion resistance of the composite coati ng was LDH/PMTMS-3 coating, which had the lowest value of corrosion current density (5.537×10^-9 A·cm^-2) and a dense surface.Plausible mechanism for coating formation and corrosion process of MTMS-modified Mg(OH)2/Mg-Al-LDH coatings were discussed.展开更多
The properties of styrene-butadiene rubber (SBR) reinforced by modified silica was investigated according to national standards. Silica was modified by silane coupling agents KH-570, KH-590, and KH-792. The optimized ...The properties of styrene-butadiene rubber (SBR) reinforced by modified silica was investigated according to national standards. Silica was modified by silane coupling agents KH-570, KH-590, and KH-792. The optimized geome-tries of molecular modified silica reinforced SBR were obtained by using B3LYP calculation of density functional theory with the 6-31+G basis sets. The natural bond orbital analyses were carried out. The Si—O bond length of silica modified by KH-792 was the shortest and the electronegative of O was the highest. It indicated that the connection between silica and KH-792 was the tightest. Higher tensile strength and elongation of reinforced SBR was obtained by silica modified with the KH-792. It was caused by large delocalization of lone pair electrons of the two N atoms in KH-792. The S—C bond length in silica modified by KH-590 was longer than the ordinary S—C bond length. Then the sulfur free radical (·S·) was produced more easily in vulcanization. The degree of crosslink was increased by the cross-linkage of the rubber molecule and the sulfur free radical. That was why the highest stress and tear strength of reinforced SBR was produced when silane coupling agent KH-590 was used. The calculation results was in accord with experimental data.展开更多
The addition of graphene oxide(GO)to cement paste significantly increases its toughness,however its fluidity is adversely affected.GO was first reacted with vinyltrimethoxysilane to produce a silane-modified graphene ...The addition of graphene oxide(GO)to cement paste significantly increases its toughness,however its fluidity is adversely affected.GO was first reacted with vinyltrimethoxysilane to produce a silane-modified graphene oxide(S-GO),which was then copolymerized with acrylic acid and a water reducing agent,isobutaenol polyoxyethylene ether(molecular mass 2400),to obtain a silane and copolymer-modified GO(P-S-GO)which acted as a water-reducing agent of the cement paste.A copolymer without GO was prepared under the same conditions for comparison.The structure,elemental composition and dispersibility of GO,S-GO and P-S-GO in a simulated cement environment(saturated lime water)were investigated by FTIR,XRD and a sedimentation test.The fluidity and rheology of the cement pastes with added GO,copolymer or P-S-GO were investigated.Results showed that vinyltrimethoxysilane reacted with the-OH group on the GO sheets to form an ether bond and the copolymer was grafted onto a vinyl group of S-GO by an addition reaction to produce the P-S-GO.The P-S-GO has a better dispersibility in saturated lime water with a negligible amount of aggregation compared to GO and a significant agglomeration occurs for GO.The addition of the P-S-GO to the cement pastes improves the fluidity and rheological properties compared with GO,offsetting the negative impact of GO and increasing the toughness of the resulting cements.展开更多
The dynamics of the Cl＋SiH4 reaction has been studied using the universal crossed molecular beam method. Angular resolved time-of-flight spectra have been measured for the channel SiH3Cl＋H. Product angular distribut...The dynamics of the Cl＋SiH4 reaction has been studied using the universal crossed molecular beam method. Angular resolved time-of-flight spectra have been measured for the channel SiH3Cl＋H. Product angular distributions as well as energy distributions in the center-ofmass frame were determined for the channel. Experimental results show that the SiH3Cl product is mainly backward scattered relative to the Cl atom beam direction, suggesting that the channel takes place via a typical SN2 type reaction mechanism.展开更多
The corrosion behavior of hot dip galvanized steel pretrvated with bis-[triethoxysilylpropyl] tetrasulfide （BTESPT） modified with alumina particles was studied. The corrosion resistance of the passiving films was ev...The corrosion behavior of hot dip galvanized steel pretrvated with bis-[triethoxysilylpropyl] tetrasulfide （BTESPT） modified with alumina particles was studied. The corrosion resistance of the passiving films was evaluated by Tafel polarization curve and electrochemical impedance spectroscopy. The films formed on the galvanized steel substrate were characterized by Fourier transform infrared spectroscopy and energy dispersive X-ray spectrometry. The surface morphology of the treated hot dip galvanized steel samples was observed by Field Emission Scanning Electron Microscope. The results show that the pretrvatments on the basis of silane films modified with nanoalumina particles have reduced both anodic and cathodic current densities, and increased total impedance in the measured frequency, consequently, improving corrosion protection for hot dip galvanized steel during immersion in NaCl solutions compared to chromate films and silane films.展开更多
An environmentally-friendly hybrid coating on AZ31 magnesium alloy substrates was reported.The synergic effect was studied on Mg−Al-layered double hydroxide Mg−Al LDH/Mg(OH)2-coated AZ31 magnesium alloy via an in-situ...An environmentally-friendly hybrid coating on AZ31 magnesium alloy substrates was reported.The synergic effect was studied on Mg−Al-layered double hydroxide Mg−Al LDH/Mg(OH)2-coated AZ31 magnesium alloy via an in-situ steam coating process and a subsequent combined surface modification of bis-[triethoxysilylpropyl]tetrasulfide(BTESPT)silane and Ce(NO3)3.The microstructure and composition characteristics of the hybrid coatings were investigated by means of X-ray diffraction(XRD),scanning electronic microscopy(SEM),Fourier transform infrared spectrophotometry(FT-IR)and X-ray photoelectron spectroscopy(XPS).The corrosion resistance of the coated samples was evaluated by potentiodynamic polarization(PDP),electrochemical impedance spectrum(EIS)and hydrogen evolution rate during immersion in 3.5 wt.%NaCl solution.The results show an improved corrosion resistance of the alloy in the presence of BTESPT silane and Ce(NO3)3.This is most likely due to the synergistic effect of steam coating and silane coating to enhance the barrier properties of hybrid coating.In addition,the formation mechanism and anti-corrosion mechanism of coatings were discussed.展开更多
The reaction of ZnO nanoparticles grafted with KH570 silane coupling agent was carried out in water-alcohol mixed solvent. Several characterization methods were applied to analyzing the results of surface modification...The reaction of ZnO nanoparticles grafted with KH570 silane coupling agent was carried out in water-alcohol mixed solvent. Several characterization methods were applied to analyzing the results of surface modification such as Soxhlet extraction, Fourier transform infrared spectroscopy （FT-IR）, transmission electron microscopy （TEM）, thermogravimetry （TG）, differential scanning calorimetry （DSC） and zeta potential （ζ）. The results of FT-IR and TG-DSC show that the desired reaction chains have been covalently bonded on the surface of ZnO nanoparticles. Zetasizer results reveal that the maximal absolute value of ζ of the modified ZnO particles in acetone medium was 67.0 mV, which was much higher than that of the unmodified ZnO particles. So the surface of nanosized ZnO changed from hydrophilicity to hydrophobicity and the dispersity of ZnO nanoparticles were improved simultaneously. Finally, the mechanism of graft modification was discussed.展开更多
文摘A visible-light-enabled method for the synthesis ofα-azidoketones has been developed via oxo-azidation of alkenyl silanes with trimethylsilylazide and molecular oxygen under mild conditions.The reaction could be carried out in gram scale.Various radical sources,including trifluoromethyl radical,thiocyanate radical,bromide radical,chlorine radical could partici-pate effectively instead of azide radical in the reaction.
基金financially supported by the National Natural Science Foundation of China(No.U23A20605)the Outstanding Youth Fund of Anhui Province(2208085J19)China Baowu Low Carbon Metallurgy Innovation Foundation(No.BWLCF202202).
文摘The incorporation of KH560-modified steel slag(MSS)as a filler in alkyd coatings significantly impacts their corrosion resistance and mechanical properties.The modification process was characterized using the Fourier transform infrared spectrometer,scanning electron microscope,and X-ray photoelectron spectroscope to understand the chemical and morphological changes induced by KH560 treatment.Three types of coatings were prepared:pure alkyd coating(AC),steel slag/alkyd coating(SS/AC),and KH560-modified steel slag/alkyd coating(MSS/AC).Their corrosion resistance was evaluated by electrochemical impedance spectroscopy and salt spray tests,while mechanical properties such as hardness,adhesion,and flexibility were also assessed.Results show that MSS significantly enhances the hardness,flexibility,and adhesion of the coatings,forming a composite structure(MSS-KH560-alkyd)that significantly improves the performance of MSS/AC.Notably,MSS/AC demonstrated superior hydrophobicity with a water absorption rate of 0.624%and a contact angle of 100.7°.Electrochemical tests revealed an impedance modulus of 3.9×10^(7)Ωcm^(2),a corrosion current of 3.39×10^(−4)mA,and a corrosion potential of−35 mV for MSS/AC.After a 10-d immersion in a 3.5 wt.%NaCl solution,MSS/AC maintained its protective properties.These findings underscore the potential of MSS as a sustainable and effective filler for alkyd coatings in corrosion protection applications.
基金the National Natural Science Foundation of China(52301107)the Joint Fund Project of Henan Provincial Science and Technology Research and Development Plan(242301420036).
文摘Magnesium alloys hold promise as biodegradable orthopedic implants but suffer from rapid corrosion and poor corrosion fatigue performance.This study evaluates the efficacy of a micro-arc oxidation(MAO)layer combined with 3-glycidyloxypropyltrimethoxysilane(GPTMS)sealing in enhancing the corrosion fatigue behavior of ZE21B magnesium alloy in Hanks’Balanced Salt Solution(HBSS).Electrochemical testing revealed a two-order-of-magnitude reduction in corrosion current density compared to bare alloy,while immersion tests demonstrated sustained protection against degradation.Corrosion fatigue experiments under cyclic loading showed stress-dependent performance:the composite coating improved fatigue life at low stress amplitudes(60 MPa)by mitigating corrosion pit formation,but interfacial weakness between GPTMS and MAO layers reduced performance at high stresses(90-80 MPa).Fractographic analysis identified asynchronous deformation and stress gradient-dependent coating spallation as key failure modes.These results provide mechanistic insights into coating degradation pathways and offer design strategies for developing robust surface modification systems to advance magnesium-based orthopedic applications.
基金supported by the Natural Science Foundation of Hunan Province(Grant No.2021JJ40463).
文摘With the rapid development of flexible wearable electronic products,their application fields and demands are increasing,posing new challenges to flexible conductive materials.This paper selected flexible polydimethylsiloxane(PDMS)as the substrate.In order to enhance the adhesion between the substrate and the metal coating,dopamine and silanization were used to co-modify its surface.A conductive layer of metallic copper is deposited on its surface using an inexpensive,easy-to-use electroless plating technique.By optimizing the process conditions,it is found that a uniform copper layer of about 0.6μm can be formed on the surface of the substrate by electroless plating at a constant temperature of 45℃ for 30 min with a conductivity of 5556 S/cm.The relative resistance changes under different deformation conditions,and the I-V curve of the LED circuit is not very different.Therefore,this paper prepared a flexible conductor with excellent electrical conductivity,high coating adhesion,and good electrical stability under large-scale deformation.
基金Funded by the Basic Scientific Research of Liaoning Provincial Department of Education(No.LJ212410153030)。
文摘An environmentally friendly waterborne polyurethane(CWPU)emulsion was developed via a dual modification strategy by combining both the silane coupling agent KH-602 with renewable castor oil(CO)as a sustainable substitute for petroleum-based polyols.The resulting materials were thoroughly characterized using Fourier-transform infrared spectroscopy(FTIR),thermogravimetric analysis(TGA),and differential scanning calorimetry(DSC).Furthermore,the influence of KH-602 content on the material properties was systematically investigated.The experimental results reveal that the incorporation of KH-602 significantly improves the thermal stability of the composite coating.As the KH-602 content increases,the tensile strength exhibits a gradual enhancement,while the elongation at break displays an initial increase followed by a subsequent decline.At an optimal KH-602 content of 3%,the coating demonstrates a balanced performance,achieving a tensile strength of 14.19 MPa and an elongation at break of 731.12%.These results suggest that the dual modification approach enhances mechanical and thermal properties while maintaining water resistance,making it suitable for sustainable coating applications.
基金financially supported by the National Natural Science Foundation of China(No.52075391).
文摘The new energy vehicle body composed of multi-metals requires a synchronous chemical conversion coating to exhibit excellent corrosion resistance.Herein,we prepared a titanium/zirconium/water-based oligomeric epoxy silane composite chemical conversion coating on multi-metals,and conducted an investigation into its electrochemical behavior and micro-zone structural characteristics upon immersion in a 3.5%NaCl solution.The electrochemical results combined with characterization results revealed that the corrosion evolution characteristics of the composite coatings could be categorized into three stages of mild corrosion,synergistic protection,and substrate damage.Besides,Si-OH groups interact with Me-OH at the defect on the multi-metal surface to form an organic monolayer coating.This organic monolayer coating,in conjunction with the synergistic inorganic conversion layer comprising Al_(2)O_(3),TiO_(2),2H_(2)O,ZrO_(2),2H_(2)O,effectively cooperates with the corrosion products to hinder the erosion by the corrosive medium and suppresses the progression of the anodic reaction.
基金Supported by the Ministry of Science and Technology of China(G1999022406)the BP China Joint Center.
文摘The direct conversion of methane into aromatics under non-oxidative conditions has received considerable attention since 1993^[1-3].Mo/HZSM-5 is the best one among the tested catalysts.It is generally accepted that the activation of the C-H bond of methane and initial C-C bond formation occur on Mocarbides formed from the reduction of Mo O,species,while the further transformation of C^(2+)hydrocarbons occurs on the Bronsted acid sites of HZSM-5 zeolite^[4].The unique channel structure of HZSM-5 plays a crucial role in constraining side reactions and controlling the product distribution^[5].The Bronsted acid sites of HZSM-5 are also responsible for the for-mation of carbonaceous deposits[6].
文摘Aim To determine the effect of silane grafted polypropylene on the property of different filler/polypropylene composites. Methods Polypropylene (PP) composites filled with talc(Ta), baryta sulfate and calcium carbonate coupled with silane grafted polypropylene (PP-g-Si) were made, their mechanical properties and thermal properties were investigated, respectively. Results As compared with the non-coupled composites, the mechanical properties of PP/Ta/PP-g-Si composites were improved to some extent, though the values of tensile modulus and the strain at peak were decreased. But for PP/BaSO4 and PP/CaCO3 composites, the values of their mechanical properties varied slightly or even decreased with increasing PP-g-Si content within the experimental component. Meanwhile, PP-g-Si also affected the melting and crystallization behavior of PP in the composites. Conclusion PP-g-Si offers compatibilization in PP/Ta composites, but offers no-compatibilization in PP/BaSO4 and PP/CaCO3 composites within the extent of the present range of PP-g-Si, which shows that PP-g-Si can be used as the macromolecular coupling agent of PP and Ta composite.
文摘Novel hollow Fe3O4 nanoparticles for drug delivery were synthesized via a one-step template- free approach. These nanoparticles were obtained by modifing the Fe3O4 nanoparticles with 3-aminopropyltrimethoxy silane, and then grafting alginate onto the surface of amine magnetic. The hollow structure of Fe3O4 spheres was characterized by TEM, XRD, and XPS. The M-H hysteresis loop indicated that the magnetic spheres exhibit snperparamagnetic characteristics at room temperature. Daunorubicin acting as a model drug was loaded into the carrier, and the maximum percent of envelop and load were 28.4% and 14.2% respectively. The drug controlled releasing behaviors of the carriers were compared in different pH media.
文摘The present work aimed at using rare earth lanthanum salt and trimethoxy（viny）silance as chromate substitutes for galvanized steel passivation, in contrast to zinc coating samples treated with chromate.The corrosion resistance was assessed by electrochemical impedance spectroscopy（EIS） and neutral salt spray tests（NSS）.Scanning electron microscopy（SEM） was used to characterize the sample surfaces.The organic coating adhesion on the panel was also investigated via varnishes-cross cut tests.The results indicated that rare earth and silane two-step treatment gave more effective anticorrosion performance than Cr, which also provided good paint adhesion.The coating formation mechanism was also discussed.
基金supported by the Provincial Natural Science Foundation of Hunan Province (04JJ30817)
文摘Bis-3-(triethoxysilyl)propyltetrasulfide(BTESPT) silane-rare earth cerium composite coatings on aluminum-tube were prepared at 60 °C by immersion method.The performance of composite coatings to protect the aluminum-tube against corrosion was investigated with potentiodynamic polarization curves,electrochemical impedance spectroscopy(EIS),and salt spray test(SST).The results of potentiodynamic polarization curves and EIS indicated that the self-corrosion current decreased by two orders of magnitude and the i...
基金supported by the United Nations Common Fund for Commodities (CFC/LZSG/12)
文摘A complex film on hot-dip galvanized steel sheet（HDG） was prepared by immersing the sheet in 0.1wt.% Ce（NO3）3 solution and 5vol.% silane solution in turn.The corrosion protection of the complex film was evaluated by potentiodynamic linear polarization（LPR）, electrochemical impendence spectra（EIS） and natural salt spray（NSS） tests and compared with that of single cerium film and silane film.The results showed that, the presence of these films on the zinc coating hindered corrosion reaction by reducing the rate of both anodic and cathodic reaction in the corrosion process, and the corrosion protection of the complex film was much better than that of single cerium film or silane film and closed to that of chromate film, because the polarization resistance Rp and electrochemical impendence were increased markedly.Microstructure and chemical composition of these pretreated films were also investigated by scanning electron microscopy（SEM） and AES.
文摘A novel waterborne epoxy curing agent was prepared using 3-glycidoxypropyl trimethoxysilane （GPTMS） as a termination agent of adduct, which was synthesized by triethylene tetramine （TETA） and liquid epoxy resin （E-51）. The effects of the reaction temperature and time on the synthesis process were investigated experimentally. The particle size and the distribution of water dispersion of the curing agent were measured by dynamic light scattering（DLS）. The structure of the products was characterized by Fourier transform infrared spec-trometer （FTIR） and ^1H-nuclear magnetic resonance （^1H NMR）. The properties of the synthesized curing agent and the epoxy resin film cured by it were also measured. The results showed that the appropriate temperature for the synthesis of adduct was at 65-75℃ and the reaction time was 4-5h, and that the suitable reaction temperature of curing agent synthesis was 75-85℃ and the reaction time was 3-4h. When the mass ratios of GPTMS and acetic acid were 3%-5% and 5%-10% respectively, the hardness, water resistance and adhesion of the cured film were improved significantly.
基金financially supported by the National Natural Science Foundation of China (Nos.51601108 and 51571134)the Natural Science Foundation of Shandong Province (No. 2016ZRB01A62)+1 种基金the Shandong University of Science and Technology Research Fund (No. 2014TDJH104)the Opening Fund of Ministry-Province Jointly Constructed Cultivation Base for State Key Laboratory of Processing for Non-ferrous Metal and Featured Materials
文摘Mg(OH)2/Mg-Al-layered double hydroxide (LDH) coatings were modified with methyltrimethoxysilane (MTMS) on magnesium alloys. Effect of hydrolysis degree of silane solution on coating formation was investigated. Chemical compositions and surface morphologies of the coatings were examined using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and field-emission scanning electronic microscopy (FESEM). Results indicated that the composite coatings consisted of polymethyltrimethoxysilane (PMTMS), LDH and Mg(OH)2. Electrochemical and hydrogen evolution measurements revealed that the composite coatings possessed good corrosion resistance, especially the ones prepared in a high hydrolysis degree of silane. The optimum corrosion resistance of the composite coati ng was LDH/PMTMS-3 coating, which had the lowest value of corrosion current density (5.537×10^-9 A·cm^-2) and a dense surface.Plausible mechanism for coating formation and corrosion process of MTMS-modified Mg(OH)2/Mg-Al-LDH coatings were discussed.
文摘The properties of styrene-butadiene rubber (SBR) reinforced by modified silica was investigated according to national standards. Silica was modified by silane coupling agents KH-570, KH-590, and KH-792. The optimized geome-tries of molecular modified silica reinforced SBR were obtained by using B3LYP calculation of density functional theory with the 6-31+G basis sets. The natural bond orbital analyses were carried out. The Si—O bond length of silica modified by KH-792 was the shortest and the electronegative of O was the highest. It indicated that the connection between silica and KH-792 was the tightest. Higher tensile strength and elongation of reinforced SBR was obtained by silica modified with the KH-792. It was caused by large delocalization of lone pair electrons of the two N atoms in KH-792. The S—C bond length in silica modified by KH-590 was longer than the ordinary S—C bond length. Then the sulfur free radical (·S·) was produced more easily in vulcanization. The degree of crosslink was increased by the cross-linkage of the rubber molecule and the sulfur free radical. That was why the highest stress and tear strength of reinforced SBR was produced when silane coupling agent KH-590 was used. The calculation results was in accord with experimental data.
文摘The addition of graphene oxide(GO)to cement paste significantly increases its toughness,however its fluidity is adversely affected.GO was first reacted with vinyltrimethoxysilane to produce a silane-modified graphene oxide(S-GO),which was then copolymerized with acrylic acid and a water reducing agent,isobutaenol polyoxyethylene ether(molecular mass 2400),to obtain a silane and copolymer-modified GO(P-S-GO)which acted as a water-reducing agent of the cement paste.A copolymer without GO was prepared under the same conditions for comparison.The structure,elemental composition and dispersibility of GO,S-GO and P-S-GO in a simulated cement environment(saturated lime water)were investigated by FTIR,XRD and a sedimentation test.The fluidity and rheology of the cement pastes with added GO,copolymer or P-S-GO were investigated.Results showed that vinyltrimethoxysilane reacted with the-OH group on the GO sheets to form an ether bond and the copolymer was grafted onto a vinyl group of S-GO by an addition reaction to produce the P-S-GO.The P-S-GO has a better dispersibility in saturated lime water with a negligible amount of aggregation compared to GO and a significant agglomeration occurs for GO.The addition of the P-S-GO to the cement pastes improves the fluidity and rheological properties compared with GO,offsetting the negative impact of GO and increasing the toughness of the resulting cements.
基金This work is supported by the Chinese Academy of Sciences and the National Natural Science Foundation of China and the Ministry of Science and Technology.
文摘The dynamics of the Cl＋SiH4 reaction has been studied using the universal crossed molecular beam method. Angular resolved time-of-flight spectra have been measured for the channel SiH3Cl＋H. Product angular distributions as well as energy distributions in the center-ofmass frame were determined for the channel. Experimental results show that the SiH3Cl product is mainly backward scattered relative to the Cl atom beam direction, suggesting that the channel takes place via a typical SN2 type reaction mechanism.
基金the National Natural Science Foundation of China(No.50674022).
文摘The corrosion behavior of hot dip galvanized steel pretrvated with bis-[triethoxysilylpropyl] tetrasulfide （BTESPT） modified with alumina particles was studied. The corrosion resistance of the passiving films was evaluated by Tafel polarization curve and electrochemical impedance spectroscopy. The films formed on the galvanized steel substrate were characterized by Fourier transform infrared spectroscopy and energy dispersive X-ray spectrometry. The surface morphology of the treated hot dip galvanized steel samples was observed by Field Emission Scanning Electron Microscope. The results show that the pretrvatments on the basis of silane films modified with nanoalumina particles have reduced both anodic and cathodic current densities, and increased total impedance in the measured frequency, consequently, improving corrosion protection for hot dip galvanized steel during immersion in NaCl solutions compared to chromate films and silane films.
基金Projects(51601108,21676285,51571134)supported by the National Natural Science Foundation of ChinaProject(2017RCJJ015)supported by Scientific Research Foundation of Shandong University of Science and Technology for Recruited Talents,ChinaProject(2014TDJH104)supported by the Shandong University of Science and Technology Research Fund,China。
文摘An environmentally-friendly hybrid coating on AZ31 magnesium alloy substrates was reported.The synergic effect was studied on Mg−Al-layered double hydroxide Mg−Al LDH/Mg(OH)2-coated AZ31 magnesium alloy via an in-situ steam coating process and a subsequent combined surface modification of bis-[triethoxysilylpropyl]tetrasulfide(BTESPT)silane and Ce(NO3)3.The microstructure and composition characteristics of the hybrid coatings were investigated by means of X-ray diffraction(XRD),scanning electronic microscopy(SEM),Fourier transform infrared spectrophotometry(FT-IR)and X-ray photoelectron spectroscopy(XPS).The corrosion resistance of the coated samples was evaluated by potentiodynamic polarization(PDP),electrochemical impedance spectrum(EIS)and hydrogen evolution rate during immersion in 3.5 wt.%NaCl solution.The results show an improved corrosion resistance of the alloy in the presence of BTESPT silane and Ce(NO3)3.This is most likely due to the synergistic effect of steam coating and silane coating to enhance the barrier properties of hybrid coating.In addition,the formation mechanism and anti-corrosion mechanism of coatings were discussed.
基金the Foundation of National Key Technologies R&D Program-Shanghai World Exposition Special Project (Grant No.04DZ05803)the Special Project of Shanghai Nano-technology (Grant No.05nm05011)
文摘The reaction of ZnO nanoparticles grafted with KH570 silane coupling agent was carried out in water-alcohol mixed solvent. Several characterization methods were applied to analyzing the results of surface modification such as Soxhlet extraction, Fourier transform infrared spectroscopy （FT-IR）, transmission electron microscopy （TEM）, thermogravimetry （TG）, differential scanning calorimetry （DSC） and zeta potential （ζ）. The results of FT-IR and TG-DSC show that the desired reaction chains have been covalently bonded on the surface of ZnO nanoparticles. Zetasizer results reveal that the maximal absolute value of ζ of the modified ZnO particles in acetone medium was 67.0 mV, which was much higher than that of the unmodified ZnO particles. So the surface of nanosized ZnO changed from hydrophilicity to hydrophobicity and the dispersity of ZnO nanoparticles were improved simultaneously. Finally, the mechanism of graft modification was discussed.
