Improvement Mechanism of Adhesion Performance of Anti-stripping Agents and Coupling Agents on Asphalt-Aggregate Interface Based on Molecular Dynamics

This study examined the mechanisms for improving the adhesion performance of the asphalt-aggregate interface with two anti-stripping agents and two coupling agents.The investigation of contact behavior between various asphalt-aggregate surfaces was conducted using molecular dynamics(MD)simulations.The interaction energy and the relative concentration distribution were employed as the parameters to analyze the enhancement mechanisms of anti-stripping agents and coupling agents on the asphalt-aggregate interface.Results indicated that the adhesion at the asphalt-aggregate interface could be strengthened by both anti-stripping agents and coupling agents.Anti-stripping agents primarily improve adhesion through the reinforcement of electrostatic attraction,while coupling agents primarily upgrade adhesion by strengthening the van der Waals.Hence,the molecular dynamics modeling and calculation techniques presented in this study can be utilized to elucidate the development mechanism of the asphalt-aggregate interface through the use of anti-stripping agents and coupling agents.

A novel high-efficient P/N/Si-containing APP-based flame retardant with a silane coupling agent in its molecular structure for epoxy resin

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.

Nanolignin,a Coupling Bio-Agent for Wood-Plastic Composites

The influence of nanolignin coupling bio-agent on some characteristics of polypropylene-wood flour composites was studied.Thus,nanolignin was prepared by the acidic method,and then different ratios of it(0,1,3 and 5 wt%)were added to a polypropylene-wood flour mixture.After mechanically mixing wood flour,nanolignin,and polypropylene,the mixture was injection molded.ASTM methods were used to measure the structural properties of nanolignin,and prepared composites’water absorption,thickness swelling,bending modulus,and bending,tensile and impact strengths.Transforming the original lignin to nanolignin did not change the chemical bonds of the material.The addition of nanolignin yielded improved mechanical and physical properties of the composites prepared.Higher strength and dimensional stability are presented by nanolignin-containing composites when comparing them with those prepared with normal lignin.Nanolignin was shown by SEM(Scanning Electron Microscope)observation to be uniformly dispersed within the polymer matrix.Wood polymer composites(WPCs)with nanolignin exhibited comparable properties with the control samples prepared using maleic anhydride polypropylene(MAPP).

Effect of Silane Coupling Agent Concentration on Interfacial Properties of Basalt Fiber Reinforced Composites

The purpose of this study is to investigate the effect of the concentration of silane coupling solution on the tensile strength of basalt fiber and the interfacial properties of basalt fiber reinforced polymer composites.The surface treatment of basalt fibers was carried out using an aqueous alcohol solution method.Basalt fibers were subjected to surface treatment with 3-Methacryloxypropyl trimethoxy silane at 0.5 wt.%,1 wt.%,2 wt.%,4 wt.%and 10 wt.%.The basalt monofilament tensile tests were carried out to investigate the variation in strength with the concentration of the silane coupling agent.The microdroplet test was performed to examine the effect of the concentration of the silane coupling agent on interfacial strength of basalt reinforced polymer composites.The film was formed on the surface of the basalt fiber treated silane coupling agent solution.The tensile strength of basalt fiber increased because the damaged fiber surface was repaired by the firm of silane coupling agent.The firm was effective in not only the surface protection of basalt fiber but also the improvement on the interfacial strength of fiber-matrix interface.However,the surface treatment using the high concentration silane coupling agent solution has an adverse effect on the mechanical properties of the composite materials,because of causing the degradation of the interfacial strength of the composite materials.

Graft modification of ZnO nanoparticles with silane coupling agent KH570 in mixed solvent

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.

Influence of silane coupling agent on the conversion film forming of galvanized steel treated with cerium salt

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.

Reinforcement of Styrene-Butadiene Rubber with Silica Modified by Silane Coupling Agents: Experimental and Theoretical Chemistry Study

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.

Surface Modification of Fire-retardant Asphalt with Silane Coupling Agent

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.

ON PHENYLSILANE TYPE COUPLING AGENTS AND THEIR APPLICATION IN COMPOSITE

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).

EFFECTS OF COUPLING AGENTS ON THE CRYSTALLIZATION BEHAVIOR OF PP/T-ZnOw COMPOSITES

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.

Dispersion of graphene in silane coupling agent aqueous solutions

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.

Improvement of the FRP Sheet Bonded to Concrete Substrate by Silane Coupling Agent

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.

Preliminary study of the effects of EVA coupling agents on properties of wood-plastic composites

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.

EFFECTS OF COUPLING AGENTS ON THE RHEOLOGICAL BEHAVIOR OF KAOLIN FILLED POLYAMIDE 6

An experimental study was carried out to investigate the effects of coupling agents on the rheological properties of kaolin filled polyamide 6(PA6). We have investigated the state of dispersion and interfacial interaction of the filled systems, using 'h:anning electron microscopy (SEM) and Molau test, respectively. It is found that the addition of the coupling agents to the PA6/ kaolin (20 wt percent) significantly decreases the melt viscosity and the melt elasticity (first normal stress difference). Moreover, the states of dispersion and the polymer/filler interactions have significant influences on the rheological properties of kaolin/PA6 systems. The rheological behavior of KH550 kaolin /PA6 system is different from that of KH560 kaolin/PA6 system, although chemical reactions have taken place between the surface of KH550 kaolin (or KH560 kaolin) and PA6 matrix during melt processing. This is attributable, in part, to the differences in the state of dispersion of kaolins in PA6 matrix and, to a great extent, to the differences in the extent of chemical reactions that have taken place between the filler and polymer matrix.

Coupling of anionic wetting agents to dust of sulfide ores by dropping liquid method

By using the experimental approach of dropping liquid, the coupling of three anionic wetting agents with ten dust samples of sulfide ores was studied, and particularly the wetting effects of the wetting agents on the sulfide dust influenced by factors of agent concentration and sulfate additive in the wetting agent solutions were investigated. The results show that when the solution temperature is about 20 ℃, all the selected wetting agents are effective to most dust samples, but the effect is different. Wetting agents are more effective to the dust which is difficult to be wetted. Wetting agent solution with sodium sulfate can improve the wetting ability of sulfide dust. For sodium dodecyl benzene sulfonate, the suitable concentration of sodium sulfate is 12 mmol/L. The cost of wetting agents can be reduced because the sodium sulfate is much cheaper than many surfactants. Since the dust of sulfide ores is composed of various minerals and elements, the whole effect of depressing dust should be considered while innovating a wetting agent.

Improving the Combined State of Rubber-Clay CompositeInterface by Applying Coupling Agent

The surface modification of clay fines was carried out by using silanecoupling agent. By means of IR spectra etc, a study was made on the combined state ofcoupling agent and clay. A rubber--clay composite material with excellent performancehas been prepared.

Surface organic modification of Fe_3O_4 nanoparticles by silane-coupling agents

Fe3O4 nanoparticles were prepared by chemistry co-precipitation and the mean crystal size was 17.9 nm measured by XRD. After it had been treated by silane-coupling agents KH570, magnetic micro-spheres dispersed in organic medium glycol were gained and the mean size of Fe3O4 nanopowders was 33.7 nm. So it can be concluded that magnetic micro-sphere is made of a few Fe3O4 crystals. Many factors of modification were researched, such as the time of ball milling, the content of Fe3O4 and the content of KH570. The modification of Fe3O4 is relative to the time of ball milling, but the dominant function is affected by the content of Fe3O4 and KH570. When the content of Fe3O4 is known, there is a suitable content of KH570. Different content of Fe3O4 will make the different suitable content of KH570, but the range of latter is less than former, which is relative to the distribution of KH570 on Fe3O4 surface or in the solution.

The Coupling Agents' Effects on the BSA Intercalated into Montmorillonite

The effects of surface modification on montmorillonite （MMT） were illustrated in order to produce the composite material with premium properties. MMT was treated with two coupling agents： glutaraldehyde （GA） and 7-methacryloxy-propyl-trimethoxy silane （KH570）. The effects of different coupling agents on MMT and protein interaction were investigated by XRD, FT-IR, TGA, UV-Vis, etc. The results of structure characterization indicated that KH570 modification could change the surface crystal structure of MMT. However, GA reacted with amino groups of Bovine serum albumin （BSA） and the ordered layer structures of MMT were not completely destroyed. Coupling agents could greatly increase the amounts of BSA intercalated and the effect of KH570 is better than that of GA. And, the optimum concentrations of KH570 and GA were 2% and 6%, respectively. The rate of weight loss increased by about 12% after MMT was pretreated with coupling agents. The possible reason is that coupling agent treatment makes the structure of MMT more accessible to protein absorption and helps to stabilize the protein structure. Moreover,the presence of coupling agents can reduce the direct chemical interaction between BSA and MMT, which results in increasing protein desorption.

A STUDY OF THE STRUCTURAL LAYERS OF COUPLING AGENTS AND THE MICROSCOPIC RHEOLOGY IN THE INTERFACES OF GF/UP SYSTEMS

The coupling agents content and thickness on glass fiber (GF) surfaces which have been treated with silanes and titanates under different conditions are tested by means of XRF (X-Ray Fluorescent spectrometry). And the rheological characteristics of the dispersed systems prepared from the above glass fibers combined with unsaturated polyester resin (UP) are discussed. The results show that the rigidity of the internal layers of silane coupling agent absorbed by glass surfaces is greater than the one of the external layers; while the effect of the titanate coupling agents on the rheolo- gical characteristics of the system is approximately the same in each structural layer, that is due to the fact that both the internal and external layers of titanates on glass surfaces have the similar flexible structures.

Chemical Reaction Between Polyvinyl Alcohol and Titanate Coupling Agent with X-Ray Photoelectron Spectroscopy

The chemical reaction between polyvinyl alcohol (PVA) and tri(dioctylpyrophosphoryloxy) isopropyl titanate (NDZ-201) was studied using X-ray photoelectron spectroscopy (XPS).The results show that some C-OH functional groups of PVA react with the titanate coupling agent to form C PVA-O-Ti-O-C PVA bond.The cross-linking of the PVA chains occurs through the formation of C PVA-O-Ti-O-C PVA bonds and produces a three dimensional hydrophobic polymer network.Accordingly,the mechanism is proposed that the titanate coupling agent improves the moisture sensitivity of high alumina cement/polyvinyl alcohol (HAC/PVA) based macro defect free (MDF) composite material.