Silicon Coupling Agent Research Articles

Influences of Ion Abundance of Cationic Hydrophilic Polyurethane Modified with Polysiloxane on its Emulsion Properties

Several cationic water-based polyurethanes end-capped with silicone coupling agent with different ion abundance are prepared. The effects of ion abundance of those polyurethanes on its emulsion particle size distribution, wet rubbing fastness improvement, hydrophility and soft handle are studied. The results show that the sample with moderate cationic ion abundance has optimal efficiency for color fixing of reactive dyes, and the quaterized cationic groups in polyurethane molecule should has positive contribution to hydrophility and soft handle of the treated fabric, especially for the color fabric treated with higher concentration polyurethane emulsion.

Role of fiber/matrix interphases on dielectric, friction, and mechanical properties of glass fiber-reinforced epoxy composites

This study compares the mechanical, tribological, and dielectric properties of glass fiber-reinforced epoxy (GFRE), presenting various fiber/matrix adhesions. Three GFRE composites were studied. The only difference between them is in the initial preparation of fibers which is intentionally simplified compared to the complex sizings used in industry. Thus, fibers treated with aminosilane or silicone coupling agents were compared with fibers simply washed with deionized water. The dielectric measurements show the leading role of interfacial bonding in the trapping or diffusion of electric charges. To obtain high mechanical properties, a fiber treatment that contributes to the diffusion of electric charges along the fiber/matrix interface is preferred. In addition, after friction, a modification of the dielectric properties in all materials is observed, and the trapping or the diffusion of the charges along the interfaces can make it possible to lower the friction coefficient, or the wear.

The Preparation of Mica Composite Insulation Material with Starch Adhesive and its Modified Enhancement

Silicone resin is the mainly adhesive in mica insulation industry, and this sort of adhesive is easy to produce toxic and harmful volatile organic compounds and causing the environment pollution. Under the premise of no decrease in insulation performance of the mica composite insulation material, the environmental friendly modified starch adhesive is chosen. In order to obtain the high performance composite materials, the improvement of its flexural strength is necessary, and the method of modification is introduced. Four kinds of modified starch, such as: maize soluble starch, oxidized starch, β-dextrin and cationic starch are discussed. The cationic starch is avaliable as the bond medium and the silicone coupling agent KH-550 is used for modified enhancement. When the dosage of the cationic starch is 10% and modified 30mins by silicone coupling agent KH-550 with the concentration of 1%, the flexural strength and dielectric strength of the mica composite insulation material can reach 248.5 N/mm2and 23.16 KV/mm respectively.

Research on Compound Powder of Bonded NdFeB Magnets from Injection Molding

The injection molding of magnetic powder could cost-effectively mass-produce net shape magnets. In order to prepare the injection molding bonded NdFeB permanent magnet material with better combined properties, the effect of binder on the magnetic property, mechanical property and fluidity of injection molding magnets and its mechanism microcosmically were investigated. The effect of additives such as silicone coupling agent, compound lubricants and antioxidant on the properties of injection molding magnets are discussed. The injection molding bonded magnets were prepared by using the MQP-B rapidly quenching NdFeB magnetic powder and polyamide 12. The magnetic properties are :Br=0.539T, Hcb=345.37kA/m, Hci=681.02kA/m, and (BH)max=47.37kJ/m3.

UV aging resistance properties of PBO fiber coated with nano‐ZnO hybrid sizing

AbstractIn this article, we focus on the ultraviolet (UV) shielding efficiency for poly(p‐phenylene‐2,6‐benzobisoxazole) (PBO) fiber with zinc oxide (ZnO) nanoparticle/epoxy hybrid coating. ZnO nano particles were initially functionalized with silicon coupling agent for improving their dispersion and surface reactivity, and then they were hybridized with epoxy resin by grafting on the ZnO nano particles. The hybrid reactions have been indicated by means of Fourier transform infrared spectrometer (FT‐IR). Its UV light shielding effect of the hybrid coating on PBO fiber properties has been studied using ultraviolet spectrum, tensile test, atomic force microscopy (AFM), and X‐ray photoelectron spectroscopy (XPS). Results showed that the surface topographic, the surface polymer structure, and the tensile strength of coated PBO fiber were less declined than that of uncoated fiber by UV light. From these results, the nano‐ZnO hybrid sizing had good UV‐aging shielding efficiency for PBO fiber. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Dispersion, Mechanical and Thermal Properties of Epoxy Resin Composites Filled with the Nanometer Carbon Black

The nanometer carbon black (CB) was employed to prepare epoxy resin/carbon black (EP/CB) composites by blending-casting method. The different modified methods of silicone coupling agent were used to improve the dispersion of CB in epoxy resin. The mechanical and thermal properties of EP/CB composites were investigated. Experimental results showed that the mechanical properties increased at first, but decreased with excessive addition of CB. When the mass fraction of CB was 2%, the mechanical properties were maximum. The use of modified CB significantly enhanced the mechanical properties of the composites. For given CB loading, the CB modified by pretreatment method displayed better dispersion in the epoxy resin than that of the direct mixing method. SEM observation revealed that the tensile fracture surface of the composite filled with 2 wt% modified CB held more microcracks than that of 5 wt% modified CB, and the formed microcracks could consume more energy of rupture, finally to have better tensile strength. DSC analysis showed that the glass transition temperature (Tg) of the composites increased with the increasing mass fraction of CB.

Effect of Surface Modifications on the Magnetic Properties of Ni 0.5Zn 0.5Fe 2O 4 Nanoparticles

Two different silica sources have been used for the preparation of Ni0.5Zn0.5Fe2O4/SiO2 nanocomposites, and their effects on the particle size, crystallinity and the magnetic properties have been investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and physical property measurement system (PPMS). In both cases, Ni0.5Zn0.5Fe2O4 nanoparticles of 11 nm in mean particle size were well dispersed in silica matrix. The coercivity and the blocking temperature of Ni0.5Zn0.5Fe2O4 nanoparticles modified with the silicon coupling agent show little decrease, whereas the saturation magnetization increases obviously with respect to nanoparticles dispersed directly in silica matrix. It is considered that the decrease of the surface anisotropy resulting from the change in the surface coordination is responsible for the observed behavior.

Preparation and atomic oxygen erosion resistance of silica film formed on silicon rubber by sol–gel method

Based on the characteristic that silicon coupling agents have the capability to develop ‘molecular bridge’ in the interface of organic materials and inorganic materials, silica films were prepared on the surface of flexible silicon rubber by sol–gel method and the optical transmittance of the sample before and after atomic oxygen irradiation was tested. The surface morphology and structure of silica films were investigated by scanning electronic microscope (SEM) and Fourier transformed infrared spectroscopy (FTIR). The results indicated that the silica sol could easily form a uniform thin film on the surface of silicon rubber pretreated by high concentration silicon coupling agents, and the inorganic silica films could combine with organic silicon rubber without obvious delamination on the interface.

The Influence of High Content Nano-Al2O3 on the Properties of Epoxy Resin Composites

The nano-alumina (nano-Al2O3) particles were modified by silicon coupling agent KH-550, and the epoxy matrix nanocomposites were prepared by using nano-Al2O3 as reinforcing agent. The dispersion status was studied by transmission electron microscope (TEM). On this basis, effects of nano-Al2O3 content on dielectric and mechanical properties of the nanocomposites were studied. Morphologies of the fracture surface of nano-Al2O3/epoxy composites were observed by scanning electron microscope (SEM). As a result, the mechanical properties reached to the best when the nano-Al2O3 content is 20%. The impact strength, flexural modulus and flexural strength increased by 84%, 29% and 18% respectively. The relative dielectric constant and the dielectric loss tangent were increased with nano-Al2O3 content.

End-functional silicone coupling agent modifiedPEO/P(VDF-HFP)/SiO2 nanocomposite polymer electrolyte DSSC

The end-functional silicone coupling agent (dodecyl-trimethoxysilane, DTMS for short) was used to modifythe PEO/P(VDF-HFP)/SiO2 nanocomposite polymer electrolyte (CPE) and the different amounts of DTMS modification effectswere studied. The experiments showed the silicone coupling agent with hydrophobic alkyl chains(–C12H25) chemicallyengineered on the SiO2 nanoparticles, and formed a Si–O–Si cross-linked network in the new nanocompositepolymer electrolyte. Proper content of DTMS modified CPE exhibited improved ionicconductivity and the connection with the photoanode and counter electrode. However,much higher content of the DTMS modification changed the conformation of the polymernetwork and reduced the ionic movement. Compared with the performance (3.84%) of theoriginal DSSC, the DSSC with functional silicone coupling agent modified CPE(DTMS:SiO2 = 2:1, mol ratio)exhibited improved Jsc (7.94 mA cm−2), Voc (0.624 V) and optimal efficiency (5.2%) (measured at AM1.5, light intensity of58.4 mW cm−2).The Voc of the silicone coupling agent modified polymer electrolyte DSSC is obviouslyimproved, which is mainly due to that the hydrophobic alkyl chain end groupsformed an insulating layer that retarded the electron recombination at theTiO2 nanoporous photoanode/polymer electrolyte interface. TheDTMS:SiO2 = 2:1 modified CPE type DSSC exhibited a performance of 6.42% at a light intensity of32.1 mW cm−2 and4.94% at 99.2 mW cm−2.

The preparation of composites of poly(N‐isopropylacrylamide) with silica and its application in HPLC for separating naphthalene derivatives

AbstractIn this study thermosensitive composites were prepared through grafting copolymerization of N‐isopropylacrylamide (NIPAM) with [3‐(methacryloyloxy) propyl] trimethoxysilane (MOPT, a silicon coupling agent) coupled on the surface of ultrafine silica beads. The effects of some synthetic conditions such as stabilizers, solvents, initiator, feed ratio on the grafting yields were investigated. The structures of the composites were characterized by infrared spectra, differential scanning calorimetry, and scanning electron microscope. The thermosensitive composite was used as a packing material in high performance liquid chromatography for separating naphthalene derivatives. The result indicated that satisfactory separation was achieved by controlling temperature of the column. As a comparison the packing material of silica‐MOPT has no this separating efficiency due to absence of thermosensitivety. The mechanism for the temperature‐controlled separation is attributed to polarity change of the poly(N‐isopropylacrylamide) (PNIPAM) on silica surface when PNIPAM undergoes volume phase transition. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers

THE DESIGN OF SURFACE MODIFICATION OF AMORPHOUS ZrO2 NANOPARTICLES AS A LUBRICANT ADDITIVE

ZrO 2 is a kind of inorganic material with high hardness, high tenacity, antiwear, corrosion, and resistance, therefore it is regarded as an ideal nanolubricant material. But untreated ZrO 2 nanoparticles are reunited in the lubricant medium instead of monodisperse because the consistency is poor between the material surface and lubricant, which restricts its application as a nanolubricant additive. Through theoretical analysis, this paper designed that the surface of ZrO 2 nanoparticles was modified with silicon coupling agent, and it was changed to lipophilic surface, so it was possible to be a monodisperse system in the lubricant. The modified spherical nanoparticles of ZrO 2 were dispersed in the lubricant and they could play a molecular bearing part in lubricating media. When the friction surface reached a certain load and temperature, once the metal surface produces the deficiency, physical adsorption and chemisorption on the metal surface would be produced because of high nano- ZrO 2 particle activity, and even the N atom in the particle surface silane tends to be absorbed to the metal surface to form chelate compound, and make ZrO 2 particles enrich to defective locations of the metal surface. Then, a self-repairing lubricated membrane in the friction surfaces was set up, and it can play the function in the antifriction, antiwear, and surface dynamic self-repair.

Mechanical properties of nanohydroxyapatite reinforced poly(vinyl alcohol) gel composites as biomaterial

Nanohydroxyapatite reinforced poly(vinyl alcohol) gel (nano-HA/PVA gel) composites has been proposed as a promising biomaterial, especially used as an articular cartilage repair biomaterial. In this paper, nano-HA/PVA gel composites were prepared from mixing nano-HA particles modified by silicon coupling agent, with physiological saline solution (PSS) of PVA by freezing-thawing method. The effects of various factors on the mechanical properties of nano-HA/PVA gel composites were evaluated. It was shown that the mechanical behavior of nano-HA/PVA gel composites was similar to that of natural articular cartilage, which held special viscoelastic characteristics. The tensile strength and tensile modulus of the composites improved correspondingly with the increase of freezing-thawing times and concentration of PVA solution. The more concentration of PVA solution, the higher influence degree of concentration on the tensile strength of composites is. The tensile strength and tensile modulus of nano-HA/PVA hydrogel composites increased first and then decreased with the rising nano-HA content of the composites. The tensile modulus of the composites improved remarkably with the increase of elongation ratio.

Special epoxy silicone adhesive for inertial confinement fusion experiment

The effects of toughener and coupling agent on special epoxy silicone adhesive were discussed by researching the surface morphology characters, thermal properties and shear strength of the adhesive. The results indicate that silicone coupling agent (KH-550) can improve the shear strength of the epoxy silicone adhesive effectively. The mass fraction of the toughener in the epoxy silicone adhesive plays an important role in its properties. When the mass fraction of the toughener is less than 14%, the shear strength of the adhesive is low. When the mass fraction of the toughener is over 33%, thermal properties and shear strength of the adhesive decrease with the increasing of the toughener. The mass fraction of toughener of 25% results in good integral properties of the epoxy silicone adhesive. The morphologic analysis indicates that the micro-phase separation exists in the epoxy molecular chain and the silicone molecular chain of the epoxy silicone adhesive.

Fundamental studies of a new hybrid (inorganic–organic) positively charged membrane. II. Membrane preparation via alcoholysis reaction and amination processes of silicone and titanate coupling agents

A series of novel inorganic–organic hybrid positively charged membranes were prepared by coupling of 3-glycidoxypropyltrimethoxysilane (GPTMS) and mixed GPTMS/Ti(O- n-C 4H 9) 4 in n-butyl alcohol (BuOH) solution at various temperatures and then followed quaternary amination with trimethyl amine (TMA). The synthesized membranes were characterized by IEC, streaming potential, pure water flux, FT-IR, TGA measurements as well as SEM observations. It was exhibited that anion exchange capacities (IECs) of the membranes decreased with increasing curing temperature within a range of (1.4–3.1) × 10 −2 mequiv. cm −2 coated for one time and (3.5–4.6) × 10 −2 mequiv. cm −2 coated for two times. The positive charge of the membranes was approved by these IEC values as well as FT-IR spectrum of step products and streaming potential values. The thermal stability was tested by TGA analysis and showed that the membranes doped with titanium could undergo a curing temperature up to 300 °C. Pure water flux showed that they decreased with increasing curing temperature, the composition of precursor and dip-coating times, respectively. SEM observations indicated that the membranes became thicker and denser with increasing content of titanium, but excessive Ti-content would decrease the stability of Si O Ti bonds in the membranes.

Synthesis and characterization of poly(methyl methacrylate)/montmorillonite nanocomposites by in situ bulk polymerization

AbstractPoly(methyl methacrylate)/montmorillonite (MMT) nanocomposites were prepared by in situ bulk polymerization. The results showed that the silicone coupling agent affected the structure and properties of hybrid materials. XRD analysis showed that the dispersion of clay in nanocomposites with silicone‐modified organophilic MMT was more ordered than that in nanocomposites with unmodified organophilic MMT. The glass transition temperature (Tg) of the nanocomposites was 6–15°C higher and the thermal decomposition temperature (Td) was 100–120°C higher than those of pure PMMA. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2256–2260, 2003

Organophosphorus-Based Organic / Inorganic Hybrids

ABSTRACTThis paper is a concise review of some recent works which highlights the interest of phosphonate groups RP (O)32- in the field of organic/inorganic hybrid materials, as a general alternative to silicon coupling agents in anchoring of an organic group to an inorganic support or within an inorganic network. Examples, focused on metals of groups 4 and 13, illustrate various synthetic routes, from the hydrothermal synthesis of two- or three-dimensional metal phosphonates, to the introduction of organic moieties into oxide matrices by sol-gel processing, without excluding the grafting of metal oxide surfaces.

Effect of coupling agents on mechanical property of AN/PU energy Composite

Silicon and titanate coupling agents are used to process the surface of ammonium nitrate (AN) particles in order to decrease their surface tension, improve affinity to the adhesive and the adhesive strength of the surface, and improve the mechanical property of an AN/polyurethane (PU) energy composite. SEM and ESCA analyses verify the effect of coupling agents on the mechanical property of the AN/PU energy composite.

Robust titanate-modified encapsulants for high voltage potting application of multichip module/hybrid IC

High-voltage gated-diode-crosspoint (GDX) devices (operation at 375-V) for AT&Ts No. 5 electronic switching system (ESS), which require exceptional protection, are considered. Heat-curable silicone elastomer appears to be the ideal material for this application. The material formulation includes small amounts of a silane coupling agent which increases material adhesion to the potted multichip module (MCM)/hybrid integrated circuit (HIC) structure. However, residual silicone coupling agent tends to defuse to outer casings, thereby contaminating leads and preventing further lead attach assembly. Titanate modified silicone elastomer was developed which prevents silane coupling agent contamination and also further improves adhesion within the potted structure. Fourier-transform infrared (FT-IR) and gas chromatography mass spectrometry (GC/MS) analyses of contaminants are described. A solution that achieves a robust potted GDX MCM HIC is described. Laser ionization mass spectrometry (LIMA) analysis was used to elucidate the additional titanate interaction with the potting compound.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The wetting of silicon carbide surfaces

Abstract Silicon carbide fibers, 3 mil in diameter, produced by thermal decomposition of dichloromethylsilane on a tungsten substrate, have a relatively smooth surface. This is shown by close agreement of the measured specific surface area, 0.016 m 2 /gm ± 0.02 m 2 /gm with the calculated geometric specific surface area, 0.04 m 2 /gm and is supported by evidence from surface electron micrographs. Electron microprobe analysis of the fibers qualitatively showed the presence of oxygen on the fiber surface, indicating that surface oxidation of silicon carbide takes place quite readily. The critical surface tension of silicon carbide coated graphite coupons, prepared similarly to the fibers was found to be 52 ± 5 dyne/cm. The critical surface tension was not altered by exposure of the coupons to highly oxidizing conditions or to hydrofluoric acid. However, high temperature surface oxidation (air, 500°C) followed by boiling water treatment increased the critical surface tension to greater than 70 dynes/cm. The critical surface tension of a room temperature cured epoxy resin was found to be 45 ± 5 dyne/cm, indicating that an epoxy resin has a lower energy surface than untreated, oxidized, or oxidized-hydrated silicon carbide. Adhesion tension measurements between treated silicon carbide coupons and coupling agents showed that (i) oxidation and oxidation-hydration promote good adhesion of certain coupling agents to the silicon carbide surfaces, (ii) the adsorbed films are retained on the oxidized silicon carbide surfaces under rigid desorption conditions, and (iii) the “bond” between oxidized-hydrated silicon carbide surface and 4,4′-methylenedianiline was improved considerably over the “bond” between oxidized silicon carbide surface and the same compound.