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
Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing addit...Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.展开更多
BACKGROUND Ulcerative colitis(UC)is a chronic and debilitating inflammatory bowel disease.Cumulative evidence indicates that excess hydrogen peroxide,a potent neutrophilic chemotactic agent,produced by colonic epithel...BACKGROUND Ulcerative colitis(UC)is a chronic and debilitating inflammatory bowel disease.Cumulative evidence indicates that excess hydrogen peroxide,a potent neutrophilic chemotactic agent,produced by colonic epithelial cells has a causal role leading to infiltration of neutrophils into the colonic mucosa and subsequent development of UC.This evidence-based mechanism identifies hydrogen peroxide as a therapeutic target for reducing agents in the treatment of UC.CASE SUMMARY Presented is a 41-year-old female with a 26-year history of refractory UC.Having developed steroid dependence and never achieving complete remission on treatment by conventional and advanced therapies,she began treatment with oral R-dihydrolipoic acid(RDLA),a lipid-soluble reducing agent with intracellular site of action.Within a week,rectal bleeding ceased.She was asymptomatic for three years until a highly stressful experience,when she noticed blood in her stool.RDLA was discontinued,and she began treatment with oral sodium thiosulfate pentahydrate(STS),a reducing agent with extracellular site of action.After a week,rectal bleeding ceased,and she resumed oral RDLA and discontinued STS.To date,she remains asymptomatic with normal stool calprotectin while on RDLA.CONCLUSION STS and RDLA are reducing agents that serve as highly effective and safe therapy for the induction and maintenance of remission in UC,even in patients refractory or poorly controlled by conventional and advanced therapies.Should preliminary findings be validated by subsequent clinical trials,the use of reducing agents could potentially prevent thousands of colectomies and represent a paradigm shift in the treatment of UC.展开更多
The objectives of this paper are to understand the crystallization behavior of polypropylene （PP） composites with surface modified tetra-needle-shaped zinc oxide whisker （T-ZnOw）. T-ZnOw was surface modified with ...The objectives of this paper are to understand the crystallization behavior of polypropylene （PP） composites with surface modified tetra-needle-shaped zinc oxide whisker （T-ZnOw）. T-ZnOw was surface modified with different coupling agents, such as silane coupling agents （KH-550, KH-560） and titanate coupling agent （NDZ-105）, in order to improve the compatibility between PP and T-ZnOw. DSC and POM were used to characterize the melt and crystallization behavior and the crystalline structures of the composites, respectively. The results show that the surface modified T-ZnOw acts as a nucleating agent of PP crystallization, depending on the coupling agent used for modification. KH-550 and KH-560 have more apparent role in improving the interfacial interaction than NDZ-105 and induce PP crystallization at higher temperature and with smaller spherulites size. The results also suggest that the crystallization behavior depends on not only the content of coupling agent, but also the content of the surface modified T-ZnOw used in the composites.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 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
The influence of silane coupling agent on the film forming of galvanized steel treated with cerium salt was studied by scanning electron microscopy （SEM） and X-ray photoelectron spectroscopy （XPS）, and the corrosi...The influence of silane coupling agent on the film forming of galvanized steel treated with cerium salt was studied by scanning electron microscopy （SEM） and X-ray photoelectron spectroscopy （XPS）, and the corrosion resistance of conversion films was analyzed by electro interstitial scanning （EIS）. The results show that silane coupling agent KH-570 has significant influence on the compactness and homogeneity of cerium conversion films, and the process of film forming is promoted by increasing the content of tervalent and tetravalent cerium oxide. The impedance value of the cerium conversion film, especially modified with KH-570, is greater than that of the base metal, which reveals that it is necessary to add silane coupling agent to the film-forming solution in order to improve the corrosion resistance of the conversion film.展开更多
In order to reduce the agglomeration of nanographene and improve its dispersibility,six silane coupling agents were used to modify the surface of the nanographene particles.Visual inspection,Fourier-transform infrared...In order to reduce the agglomeration of nanographene and improve its dispersibility,six silane coupling agents were used to modify the surface of the nanographene particles.Visual inspection,Fourier-transform infrared spectroscopy,transmission electron microscopy,Raman spectroscopy,and X-ray diffraction were employed to evaluate the dispersion properties of the resulting graphene in an aqueous solution of silane coupling agents.Results show that all six types of silane coupling agents are efficient in promoting the dispersion of graphene in aqueous solutions,and no obvious sedimentation of the graphene dispersion solution is observed after a stationary storage period of 30 d.Taking 3-aminopropyltriethoxysilane(KH-550)as an example,after the graphene is dispersed in the KH-550 aqueous solution,the carboxyl group on the surface of the graphene reacts with the KH-550 amino group to form an amide bond,and KH-550 is successfully grafted onto the graphene surface.Polar functional groups ionize in water,creating an electrostatic repulsion effect,or hydrophilic functional groups form hydrogen bonds with water molecules,which is believed to improve the dispersion stability of graphene.The dispersed graphene is curled and contains many folds.Each fold has about three or four layers,with an interlayer spacing of about 0.65 nm.The dispersed graphene also has a complete lattice and a reduced number of defects.Nanographene disperses well in silane coupling agent aqueous solutions and can,therefore,be used to prepare cement-based composites.展开更多
The theory and approach of the surface modified of asphalt fire-retardant with silane coupling agent were introduced. The optimum silane dosage was determined, and the structure and properties of the asphalt fire-reta...The theory and approach of the surface modified of asphalt fire-retardant with silane coupling agent were introduced. The optimum silane dosage was determined, and the structure and properties of the asphalt fire-retardant before and after the surface modification were characterized by infrared spectrum and thermo gravimetric analysis. The dispersion effect of asphalt flre-retardant was studied. The influence of the surface modification on the hydrophilicity and lipophilicity of the asphalt fire-retardant was analyzed. The experimental results showed that there were physical and chemical interactions between the silane coupling agent and the asphalt fire-retardant, which reduced the surface polarity of the asphalt fire retardant. The optimum silane coupling agent dosage was 0.95% of the asphalt fire retardant. The surface modification improved the thermal stability, dispersibility and lipophilicity of the asphalt fire retardant, which enhanced the compatibility between asphalt fire retardant and asphalt.展开更多
Based on the difference of the Y-terminal functional group of the silane coupling agent(Y-Si(X)_(3)),four different silane coupling agents were employed to pretreat the surface of the NdFeB powders.The effects of sila...Based on the difference of the Y-terminal functional group of the silane coupling agent(Y-Si(X)_(3)),four different silane coupling agents were employed to pretreat the surface of the NdFeB powders.The effects of silane coupling agents on the flowability and compressibility of compounds for preparing bonded NdFeB magnets were studied.It is indicated that compounds pretreated by silane coupling agents have weaker friction and meshing force.The apparent density is increased by 0.3 g/cm^(3 )compared with the compound without silane coupling agent,and the radial crushing strength is significantly increased by about 3-4 times.In addition,the epoxy resin is more evenly distributed on the surface of the compounds treated by silane coupling agents observed by scanning electron microscopy,and some agglomerated particles are produced.Also,the compressibility of compounds with silane coupling agents is significantly improved due to the fact that hardening exponents are reduced.However,the addition of silane coupling agents has almost no effect on the magnetic properties of bonded magnets.The special energy was used to manifest the flowability of magnetic powder particles representing the macroscopic performance of the force between powder particles,providing a new direction for the study of the interface compatibility of two-phase or multiphase composite materials.展开更多
A flame retardant containing multiple antiflaming elements usually exhibits high-efficient flame retardancy. Here, a novel P/N/Si-containing ammonium polyphosphate derivative(APTES-APP) is synthesized from ammonium po...A flame retardant containing multiple antiflaming elements usually exhibits high-efficient flame retardancy. Here, a novel P/N/Si-containing ammonium polyphosphate derivative(APTES-APP) is synthesized from ammonium polyphosphate(APP) and silane coupling agent(3-aminopropyl)triethoxysilane(APTES)via cation exchange, which is quite different in the chemical structure from APTES-modified APP for retaining silicon hydroxyls. APTES-APP is highly efficient for the epoxy resin. 8%(mass) APTES-APP imparts excellent flame retardancy to the epoxy resin, with a V-0 rating at the UL-94 test(1.6 mm)and an LOI value of 26%(vol). The peak heat release rate and total smoke production of the flameretardant epoxy resin are decreased by 68.1% and 31.3%, respectively. The synergy of P/N/Si contributes to the well-expanded char residue with a strong and dense surface layer, which is a very good barrier against heat and mass transfer. Besides, there is no significant deterioration in the mechanical properties of flame-retardant epoxy resin thanks to silicon hydroxyls forming hydrogen bonds with epoxy molecules. Meanwhile, other molecules can be grafted onto APTES-APP via these silicon hydroxyls, if needed.Briefly, this work has developed a new strategy for amino silane as flame retardants. In conjunction with a low-cost and simple preparation method, APTES-APP has a promising prospect in the high-performance flame-retardant epoxy.展开更多
The chemical composition and high wear resistance of steel slag(SS)make it a potential alternative to traditional inorganic fillers.3-Aminopropyltriethoxysilane(KH550)modified steel slag(MSS)was successfully prepared,...The chemical composition and high wear resistance of steel slag(SS)make it a potential alternative to traditional inorganic fillers.3-Aminopropyltriethoxysilane(KH550)modified steel slag(MSS)was successfully prepared,and its application in epoxy(EP)anti-corrosion coating was introduced.Due to the grafting of silane coupling agent functional groups onto the surface of SS,MSS exhibited improved solubility in xylene organic solvent and reduced agglomeration.When the MSS content was 15 wt.%,the contact angle of the MSS/EP composite coating was 101°,and the abrasion was only 0.07 g,compared with 56.2°and 0.13 g,respectively,for the pure EP coating.The corrosion resistance of coatings was investigated by performing the electrochemical test(impedance)after immersion in a 3.5 wt.%NaCl solution.The electrochemical test results showed that the impedance modulus of the 15 wt.%MSS/EP composite coating at low frequency(Z_(f)=0.01 Hz)was approximately 1.08×10^(7)Ωcm^(2),which was two orders of magnitude higher than that of the pure EP coating.展开更多
In this paper, unsaturated polyester type GFRP composite was treated with phenylsilane type coupling agents by migration technology, then the mechanical properties were measured. The results show that the mechanical p...In this paper, unsaturated polyester type GFRP composite was treated with phenylsilane type coupling agents by migration technology, then the mechanical properties were measured. The results show that the mechanical properties of GFRP composite are greatly improved but the other properties are little affected after being treated by phenylsilane type coupling agents (named as WGD type coupling agents).展开更多
We experimentally studied the fine lightweight aggregate with the particle size range of 3.15-4.75 mm used as functional bridge between FRP sheet and concrete substrate. However, problems would appear and how to deal ...We experimentally studied the fine lightweight aggregate with the particle size range of 3.15-4.75 mm used as functional bridge between FRP sheet and concrete substrate. However, problems would appear and how to deal with the interfacial transition zone（ITZ） and make it stronger is the key point for this concept. Considering that silane coupling agent（SCA） can provide a better bond on a silicon-containing material surface, it was introduced as a modifying material to further improve the bond quality of the ITZ between lightweight aggregate and cement paste. Results indicated that the water absorptivity of lightweight aggregate can be controlled by SCA solutions, and the pull-off bond strength, mechanical strength, and microhardness were increased, which was attributed to the optimized microstructure under the condition of an appropriate concentration of SCA.展开更多
Nano-silica treated with different kinds of coupling agent （KH550, A-143, A-151） was used to modify the surface condition of glass fiber, and then, the modified glass fiber/unsaturated polyester resin （UPR） compos...Nano-silica treated with different kinds of coupling agent （KH550, A-143, A-151） was used to modify the surface condition of glass fiber, and then, the modified glass fiber/unsaturated polyester resin （UPR） composites materials were prepared. Scanning electron microscopy （SEM）, dynamic mechanical analysis （DMA）, and impact test were used to characterize the composite materials＇ structure and properties. The morphology of composite materials shows that the adhesion between nano-silica and glass fiber is improved when silane coupling agent is added in. The DMA and impact test results show that silane coupling agent （especially KH550 and A-151） could effectively improve the composite＇s mechanical properties. When the dose of KH550 was 0.1% （m ： m）, the storage modulus and impact strength reached the maximum.展开更多
As a hot-melt adhesive, ethylene-vinyl-acetate （EVA） has been used in many industrial applications. But studies of the application of EVA in wood-plastic composites （WPC） are relatively few, so we have investigate...As a hot-melt adhesive, ethylene-vinyl-acetate （EVA） has been used in many industrial applications. But studies of the application of EVA in wood-plastic composites （WPC） are relatively few, so we have investigated the proposition of whether EVA is a suitable coupling agent for WPC or not. The results show that EVA with 8% VA is not a suitable coupling agent, because it reduces the mechanical properties of WPC without any significant effect on its physical properties. With an increase in the amount of wood powder, the mechanical properties of WPC decrease and the ability of water absorption of WPC increases.展开更多
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National Key Research and Development Program of China(2022YFB4600902)Shandong Provincial Science Foundation for Outstanding Young Scholars(ZR2024YQ020)。
文摘Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.
文摘BACKGROUND Ulcerative colitis(UC)is a chronic and debilitating inflammatory bowel disease.Cumulative evidence indicates that excess hydrogen peroxide,a potent neutrophilic chemotactic agent,produced by colonic epithelial cells has a causal role leading to infiltration of neutrophils into the colonic mucosa and subsequent development of UC.This evidence-based mechanism identifies hydrogen peroxide as a therapeutic target for reducing agents in the treatment of UC.CASE SUMMARY Presented is a 41-year-old female with a 26-year history of refractory UC.Having developed steroid dependence and never achieving complete remission on treatment by conventional and advanced therapies,she began treatment with oral R-dihydrolipoic acid(RDLA),a lipid-soluble reducing agent with intracellular site of action.Within a week,rectal bleeding ceased.She was asymptomatic for three years until a highly stressful experience,when she noticed blood in her stool.RDLA was discontinued,and she began treatment with oral sodium thiosulfate pentahydrate(STS),a reducing agent with extracellular site of action.After a week,rectal bleeding ceased,and she resumed oral RDLA and discontinued STS.To date,she remains asymptomatic with normal stool calprotectin while on RDLA.CONCLUSION STS and RDLA are reducing agents that serve as highly effective and safe therapy for the induction and maintenance of remission in UC,even in patients refractory or poorly controlled by conventional and advanced therapies.Should preliminary findings be validated by subsequent clinical trials,the use of reducing agents could potentially prevent thousands of colectomies and represent a paradigm shift in the treatment of UC.
基金This work was supported by the National Natural Science Foundation of China(Youth Foundation:50403019)partly supported by the Opening Project of State Key Laboratory of Polymer Materials Engineering(Sichuan University).
文摘The objectives of this paper are to understand the crystallization behavior of polypropylene （PP） composites with surface modified tetra-needle-shaped zinc oxide whisker （T-ZnOw）. T-ZnOw was surface modified with different coupling agents, such as silane coupling agents （KH-550, KH-560） and titanate coupling agent （NDZ-105）, in order to improve the compatibility between PP and T-ZnOw. DSC and POM were used to characterize the melt and crystallization behavior and the crystalline structures of the composites, respectively. The results show that the surface modified T-ZnOw acts as a nucleating agent of PP crystallization, depending on the coupling agent used for modification. KH-550 and KH-560 have more apparent role in improving the interfacial interaction than NDZ-105 and induce PP crystallization at higher temperature and with smaller spherulites size. The results also suggest that the crystallization behavior depends on not only the content of coupling agent, but also the content of the surface modified T-ZnOw used in the composites.
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.
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.
文摘The influence of silane coupling agent on the film forming of galvanized steel treated with cerium salt was studied by scanning electron microscopy （SEM） and X-ray photoelectron spectroscopy （XPS）, and the corrosion resistance of conversion films was analyzed by electro interstitial scanning （EIS）. The results show that silane coupling agent KH-570 has significant influence on the compactness and homogeneity of cerium conversion films, and the process of film forming is promoted by increasing the content of tervalent and tetravalent cerium oxide. The impedance value of the cerium conversion film, especially modified with KH-570, is greater than that of the base metal, which reveals that it is necessary to add silane coupling agent to the film-forming solution in order to improve the corrosion resistance of the conversion film.
基金The National Key R&D Program of China(No.2018YFC0406701)the National Natural Science Foundation of China(No.51778133,51739008).
文摘In order to reduce the agglomeration of nanographene and improve its dispersibility,six silane coupling agents were used to modify the surface of the nanographene particles.Visual inspection,Fourier-transform infrared spectroscopy,transmission electron microscopy,Raman spectroscopy,and X-ray diffraction were employed to evaluate the dispersion properties of the resulting graphene in an aqueous solution of silane coupling agents.Results show that all six types of silane coupling agents are efficient in promoting the dispersion of graphene in aqueous solutions,and no obvious sedimentation of the graphene dispersion solution is observed after a stationary storage period of 30 d.Taking 3-aminopropyltriethoxysilane(KH-550)as an example,after the graphene is dispersed in the KH-550 aqueous solution,the carboxyl group on the surface of the graphene reacts with the KH-550 amino group to form an amide bond,and KH-550 is successfully grafted onto the graphene surface.Polar functional groups ionize in water,creating an electrostatic repulsion effect,or hydrophilic functional groups form hydrogen bonds with water molecules,which is believed to improve the dispersion stability of graphene.The dispersed graphene is curled and contains many folds.Each fold has about three or four layers,with an interlayer spacing of about 0.65 nm.The dispersed graphene also has a complete lattice and a reduced number of defects.Nanographene disperses well in silane coupling agent aqueous solutions and can,therefore,be used to prepare cement-based composites.
基金Funded by the National Natural Science Foundation of China(No.50978263)
文摘The theory and approach of the surface modified of asphalt fire-retardant with silane coupling agent were introduced. The optimum silane dosage was determined, and the structure and properties of the asphalt fire-retardant before and after the surface modification were characterized by infrared spectrum and thermo gravimetric analysis. The dispersion effect of asphalt flre-retardant was studied. The influence of the surface modification on the hydrophilicity and lipophilicity of the asphalt fire-retardant was analyzed. The experimental results showed that there were physical and chemical interactions between the silane coupling agent and the asphalt fire-retardant, which reduced the surface polarity of the asphalt fire retardant. The optimum silane coupling agent dosage was 0.95% of the asphalt fire retardant. The surface modification improved the thermal stability, dispersibility and lipophilicity of the asphalt fire retardant, which enhanced the compatibility between asphalt fire retardant and asphalt.
基金Project supported by Beijing Youth Top-notch Team Support Project of China(2018000021223TD10)Hebei Province Fund for Transformation of Major Science and Technology Achievements of China(19041029Z)Hebei Province International Science and Technology Cooperation Base Construction Project of China(20591002D)。
文摘Based on the difference of the Y-terminal functional group of the silane coupling agent(Y-Si(X)_(3)),four different silane coupling agents were employed to pretreat the surface of the NdFeB powders.The effects of silane coupling agents on the flowability and compressibility of compounds for preparing bonded NdFeB magnets were studied.It is indicated that compounds pretreated by silane coupling agents have weaker friction and meshing force.The apparent density is increased by 0.3 g/cm^(3 )compared with the compound without silane coupling agent,and the radial crushing strength is significantly increased by about 3-4 times.In addition,the epoxy resin is more evenly distributed on the surface of the compounds treated by silane coupling agents observed by scanning electron microscopy,and some agglomerated particles are produced.Also,the compressibility of compounds with silane coupling agents is significantly improved due to the fact that hardening exponents are reduced.However,the addition of silane coupling agents has almost no effect on the magnetic properties of bonded magnets.The special energy was used to manifest the flowability of magnetic powder particles representing the macroscopic performance of the force between powder particles,providing a new direction for the study of the interface compatibility of two-phase or multiphase composite materials.
基金financially supported by the National Natural Science Foundation of China (22178242)。
文摘A flame retardant containing multiple antiflaming elements usually exhibits high-efficient flame retardancy. Here, a novel P/N/Si-containing ammonium polyphosphate derivative(APTES-APP) is synthesized from ammonium polyphosphate(APP) and silane coupling agent(3-aminopropyl)triethoxysilane(APTES)via cation exchange, which is quite different in the chemical structure from APTES-modified APP for retaining silicon hydroxyls. APTES-APP is highly efficient for the epoxy resin. 8%(mass) APTES-APP imparts excellent flame retardancy to the epoxy resin, with a V-0 rating at the UL-94 test(1.6 mm)and an LOI value of 26%(vol). The peak heat release rate and total smoke production of the flameretardant epoxy resin are decreased by 68.1% and 31.3%, respectively. The synergy of P/N/Si contributes to the well-expanded char residue with a strong and dense surface layer, which is a very good barrier against heat and mass transfer. Besides, there is no significant deterioration in the mechanical properties of flame-retardant epoxy resin thanks to silicon hydroxyls forming hydrogen bonds with epoxy molecules. Meanwhile, other molecules can be grafted onto APTES-APP via these silicon hydroxyls, if needed.Briefly, this work has developed a new strategy for amino silane as flame retardants. In conjunction with a low-cost and simple preparation method, APTES-APP has a promising prospect in the high-performance flame-retardant epoxy.
基金the University Synergy Innovation Program of Anhui Province(GXXT-2020-072).
文摘The chemical composition and high wear resistance of steel slag(SS)make it a potential alternative to traditional inorganic fillers.3-Aminopropyltriethoxysilane(KH550)modified steel slag(MSS)was successfully prepared,and its application in epoxy(EP)anti-corrosion coating was introduced.Due to the grafting of silane coupling agent functional groups onto the surface of SS,MSS exhibited improved solubility in xylene organic solvent and reduced agglomeration.When the MSS content was 15 wt.%,the contact angle of the MSS/EP composite coating was 101°,and the abrasion was only 0.07 g,compared with 56.2°and 0.13 g,respectively,for the pure EP coating.The corrosion resistance of coatings was investigated by performing the electrochemical test(impedance)after immersion in a 3.5 wt.%NaCl solution.The electrochemical test results showed that the impedance modulus of the 15 wt.%MSS/EP composite coating at low frequency(Z_(f)=0.01 Hz)was approximately 1.08×10^(7)Ωcm^(2),which was two orders of magnitude higher than that of the pure EP coating.
文摘In this paper, unsaturated polyester type GFRP composite was treated with phenylsilane type coupling agents by migration technology, then the mechanical properties were measured. The results show that the mechanical properties of GFRP composite are greatly improved but the other properties are little affected after being treated by phenylsilane type coupling agents (named as WGD type coupling agents).
基金Funded by the National Natural Science Foundation of China(No.51172173)
文摘We experimentally studied the fine lightweight aggregate with the particle size range of 3.15-4.75 mm used as functional bridge between FRP sheet and concrete substrate. However, problems would appear and how to deal with the interfacial transition zone（ITZ） and make it stronger is the key point for this concept. Considering that silane coupling agent（SCA） can provide a better bond on a silicon-containing material surface, it was introduced as a modifying material to further improve the bond quality of the ITZ between lightweight aggregate and cement paste. Results indicated that the water absorptivity of lightweight aggregate can be controlled by SCA solutions, and the pull-off bond strength, mechanical strength, and microhardness were increased, which was attributed to the optimized microstructure under the condition of an appropriate concentration of SCA.
基金Supported by the National Natural Science Foundation of of China(J1210061)
文摘Nano-silica treated with different kinds of coupling agent （KH550, A-143, A-151） was used to modify the surface condition of glass fiber, and then, the modified glass fiber/unsaturated polyester resin （UPR） composites materials were prepared. Scanning electron microscopy （SEM）, dynamic mechanical analysis （DMA）, and impact test were used to characterize the composite materials＇ structure and properties. The morphology of composite materials shows that the adhesion between nano-silica and glass fiber is improved when silane coupling agent is added in. The DMA and impact test results show that silane coupling agent （especially KH550 and A-151） could effectively improve the composite＇s mechanical properties. When the dose of KH550 was 0.1% （m ： m）, the storage modulus and impact strength reached the maximum.
文摘As a hot-melt adhesive, ethylene-vinyl-acetate （EVA） has been used in many industrial applications. But studies of the application of EVA in wood-plastic composites （WPC） are relatively few, so we have investigated the proposition of whether EVA is a suitable coupling agent for WPC or not. The results show that EVA with 8% VA is not a suitable coupling agent, because it reduces the mechanical properties of WPC without any significant effect on its physical properties. With an increase in the amount of wood powder, the mechanical properties of WPC decrease and the ability of water absorption of WPC increases.
