Hydrophobic fumed silica dispersion. Through surface modification, treated fumed silica with a hydrophobic surface nature can be produced. 9 to 50 parts of water. The product thickening efficiency of AEROSIL® R 974 W ex RHE is consistent with the Waterford-produced AEROSIL® R 974. An aqueous dispersion of a hydrophobic silica consisting of 0. , isolated hydroxy, hydrogen-bonded hydroxy, and siloxane groups on the surface of fumed silica. It is produced by intensive mixing of hydrophobic silica with water with the known "dry-water-phase" as an intermediate step. RFQ NOW to get the high quality Hydrophobic Fumed Silica products and get more information. The size and structure of HFS primary particles were observed via transmission electron microscopy (TEM). 1 Substances Synonyms : Silicic anhydride Silicon dioxide amorphous Silica Silicon dioxide Silica, fumed Formula Molecular weight CAS-No. Dive into the essentials of fumed silica, focusing on its hydrophobic qualities and how it behaves with water. 3 This silica is dispersed in a variety of organic liquids, specifically a range of low molecular weight Moreover, the dynamic moduli of the hydrophobic fumed silica suspensions strongly depend on the mutual interaction between the hydrophobic moieties and the dispersion media. Their magnitudes become larger as mutual interactions increase. Herein, we have reviewed fumed silica suspensions in dispersing fluids, polymer melts, and polymer solutions, focusing on their dispersion stability and rheological properties as a function of the Hydrophobic AEROSIL® (“R“) grades have been treated during manufacture to obtain a hydrophobic surface. Our AEROSIL® fumed silica (available as untreated hydrophilic and surface-treated hydrophobic “R” types) and SIPERNAT® pre-cipitated silica are well-established problem-solvers in many industries such as food, pharmaceuticals, detergents and coatings. In addition, the aqueous dispersion is easy to disperse in water, has good dispersion stability, and is suitable to be added into systems such as paint, pigment, aqueous film material, release This study critically examines the effects of hydrophobic fumed silica, incorporated into an epoxy matrix, on the processing, moisture uptake, and mechanical properties of flax/epoxy laminates produced via resin transfer moulding (RTM). They cannot form hydrogen bonds with water, nor do they have partial charges water can interact with. requirements for water resistance, rheology, and reinforcing performance in different industries. 1). Fumed silica, also known as pyrogenic silica, is a fine powder composed of amorphous silicon dioxide (SiO2) particles that are produced by burning silicon tetrachloride in a flame of hydrogen and oxygen. The method comprises a first step wherein an aqueous suspension of fumed silica is contacted with an organosilicon compound and in the presence of a catalytic amount of an acid to effect hydrophobing of said silica. These particles can also develop a three-dimensional network through hydrophobic interactions, van der Waals forces and others. 08 g/mol : 112945-52-5 SECTION 4: First aid measures Generally speaking, hydrophobic fumed silica can be divided into two categories: hydrophilic and hydrophobic. Furthermore, the effects of polymer adsorption on the dispersion stability and rheological behavior of hydrophilic or hydrophobic silica suspensions are discussed. Aug 22, 2023 · Hydrophobic fumed silica (HFS) is a commonly used rheology additive in waterborne coatings. A new aqueous dispersion of a functionalized fumed silica has been developed using a new production process and carefully selected additives. To describe the rheological properties of dispersions containing Fumed Silica, it is essential to consider how the SiO2 particles interact with one another and with the dispersion phase. To reach this objective, they first prepared a slurry of the particles with water and a dispersant, then the slurry was added in Applying the Proper Dispersion To maximize fumed silica efficiency and to ensure performance consistency, proper dispersion is required. There are three chemical groups i. ” Hydrophobic molecules have the quality of hydrophobicity, meaning they repel water, do not dissolve in water, or are themselves repelled by water molecules. Hydrophobic fumed silica (HFS) is a commonly used rheology additive in waterborne coatings. A new feature of hydrophobic fumed silica nanoparticles (HFSNPs) when they apply to the preparation of monolithic nano-columns using narrow monolithic fused silica capillary columns (e. Because water molecules are polar, hydrophobes do not dissolve well among them. The hydrophobic nature of fumed silica is primarily due to the presence of silane compounds on its surface. e. Hydrophobic fumed silica (HFS) is a commonly used rheology additive in waterborne coatings. A method is disclosed for the preparation of hydrophobic fumed silicas which are useful as reinforcing fillers in rubber compositions. Choosing the right fumed silica is crucial! Find out if hydrophilic or hydrophobic suits your industrial needs best! Properties Specific surface area (BET) Carbon content Average primary particle size Tapped density* (approx. At these rates, minimal energy is used Fumed silica has been widely used in coatings, adhesives, and other composite materials [14,15,16,17,18,19]. The rheology of these thixotropic systems plays a major role in the effectiveness… Hydrophobic fumed silica refers to fumed silica nanoparticles that have been surface-treated to exhibit hydrophobic properties. Shear is required to obtain functionality. produced hydrophobic precipitated and fumed silica for adhesives, plastics, sealants, coatings, inks, toner, cosmetics, inks, food additives & defoamers. 3. Nov 27, 2025 · Hydrophobicity is a physical property of a molecule that causes it to be seemingly repelled from water, often described as “water-fearing. These compounds create a barrier that prevents water molecules from adhering to the silica particles. value) acc. Hydrophilic fumed silica (FS) and precipitated silica (PS) powders were suspended in mineral oil; increasing the silica volume fraction (φ in the suspension led to the formation of sol, pre-gel, and gel states. This substance which is hydrophobic due to bound hydrolysis–stable methyl groups, was intro-duced to the market in 1962 as the first commercially produced hydrophobic silica. They can form a three-dimensional network through hydrogen bonding of surface silanol groups. A specific state of the dispersion is observed at the C SiO 2 values corresponding to the bulk density of the initial silica powder. In conclusion, the choice between hydrophilic and hydrophobic fumed silica rests on a careful analysis of the product’s nature, the application system, cost considerations, and the desired dispersion method. In place of costly chemicals, easily obtainable, less expensive hydrophobic fumed silica can be applied to develop a hydrophobic surface instantaneously. 1. From the document Schriftenreihe Pigmente No. As a result, hydrophobic fumed silica can effectively reduce the viscosity of liquids and enhance the stability of emulsions. SYLOID® mesoporous silicas have been trusted solutions for drug formulations for decades and have a unique combination of properties. The PCS, 1 H NMR, and TSDC spectra demonstrate rearrangement of the fumed silica dispersion depending on the SBET value and the silica concentration (CSiO2) in the aqueous suspensions. ” This characteristic is driven by the nature of water molecules and is distinct from hydrophilicity, which describes molecules that readily mix with water. In a preferred method, the first step is Degussa Corporation produces hydrophobic fumed silica by treating the surface of hydrophilic Aerosil® to render it water repellent. Dispersion of AEROSIL® fumed s lica in the pigment grind portion is always recommended. For general-purpose ortho- and meta-benzene unsaturated resins, hydrophilic products The invention relates to a dispersion of fumed silica and to its use for producing coating materials. We therefore undertake a fundamental study on fumed silica dispersions in polar organic media. adj. Jun 16, 2022 · Hydrophobic means lacking an affinity for water; insoluble in water; repelling water. In a given case there can additionally be used a wetting agent in which case the "dry-water Hydrophobic fumed silica is a form of silicon dioxide (commonly known as silica) that has hydrophobic groups chemically bonded to the surface. Oct 1, 2020 · This historical perspective overviews the dispersion stability and rheological properties of fumed and colloidal silica suspensions in aqueous solutions as a function of the volume fraction of silica (ϕ) (where ϕ is ≤0. The addition of silica produces an increase in the storage modulus (G ') of PU adhesives, the values obtained being independent of the hydrophilic or hydrophobic nature of the fumed silica. The meaning of HYDROPHOBIC is of, relating to, or suffering from hydrophobia. Our system is based on aqueous dispersions of a polymeric binder and hydrophobic fumed silica particles, which upon drying self-organize into a micro- and nanostructured thin film with superhydrophobic properties, characterized by a water contact angle above 150° and a contact angle hysteresis below 10°. The monolithic nano-columns were synthesized by an in-situ polymerization using butyl methacrylate (BMA) and ethylene dimethacrylate (EDMA) at various concentrations of Hydrophobic fumed silica is a remarkable material that has gained significant attention in various industries, including adhesives, construction materials, and water treatment. dispersion, final letdowns with water can be conducted. Learn about and see examples of hydrophobic materials. The hydrophobic groups are normally alkyl or polydimethylsiloxane chains. Depend-ing on the coating system hydrophilic or hydrophobic AEROSIL® results in the best rheological effects. We focus exclusively on a single type of fumed silica: the native, hydrophilic variety which has silanol (Si-OH) groups on its surface. But what exactly makes this material so unique? In this article, we will delve into the properties, applications, SiSiB SILICONES offers SiSiB® FS2110 Hydrophobic Fumed Silica. Low shear dispersion with a propeller or stirring blade is insufficient shear for all AEROSIL grades and in general for all fumed silica. The surface of silica is hydrophilic, although the siloxane groups are hydrophobic Moreover, the dynamic moduli of the hydrophobic fumed silica suspensions strongly depend on the mutual interaction between the hydrophobic moieties and the dispersion media. Hydrophobic fumed silica (HFS) is an aerosol with alkanes, chloromethyl groups, or other hydrophobic functional groups on the surface [20]. The measurement … AEROSIL® fumed silica can be surface-modified by reacting the silanol groups with suitable compounds; for example, AEROSIL® R 972 is derived through the reaction with dimethyldichlorosilane. The influence of shearing magnitude on their properties was also studied. Technical Papers Process Breakthrough Makes Fumed Silica Easy-To-Disperse Easy-To-Disperse Fumed Silica Technology reduces equipment demand, processing time, and expense Abstract The field of coatings technology has utilized many forms of fumed silica in the last 70 years. 18 (April 1980) page 5, the incorporation of hydrophobic fumed silica (Aerosil® 972), together with pigments and fillers, is known. Round 1 Reviewer 1 Report In the present work, titled: Preparation and Dispersion Performance of Hydrophobic Fumed Silica Aqueous Dispersion, the authors analyze how to stabilize and get the right colloidal stability for fumed silica nanoparticles in different media. Examples of hydrophobic molecules include alkanes, oils, fats, and greasy substances in general. Peripheral velocity (tip speed) for this type of mixing is typically 5-20 ft/sec. Hydrophobes are nonpolar molecules and usually have a long chain of carbons that do not interact with water molecules. Degussa s Aerosil® P202 is treated with polymethylsiloxane (silicone oil) and Aerosil® R805 is treated with trimethoxyoctylsilane. Abstract Hydrophobic fumed silica (HFS) is a commonly used rheology additive in waterborne coatings. In addition, the aqueous dispersion is easy to disperse in water, has good dispersion stability, and is suitable to be added into systems such as paint, pigment, aqueous film material, release Hydrophobic molecules tend to be nonpolar and, thus, prefer other neutral molecules and nonpolar solvents. Mixing equipment must be capable of rapidly incorporating and dispersing the powder into the base liquid. Translations in context of "hydrophobic fumed silica" in English-Chinese from Reverso Context: AERODISP WR 8520, a new, structured silica dispersion of hydrophobic fumed silica, makes it possible to easily and effectively improve the following performance attributes in aqueous pigmented coatings and water-based clear coats Silica-based hydrophobic granular material with an increased polarity Silica-based granular material, comprising silica and at least one IR-opacifier, hydrophobized with a surface treatment agent comprising a silicon atom, wherein the granular material has: a) a cumulative pore volume of pores>4 nm of more than 2. Fumed silicas also belong to the group of inorganic, powdered rheology additives which, depending on their modification, are used in solvent-free and solvent-borne as well as in aqueous systems. The mixing of fat and water is a good example of this particular interaction. When adding the silica directly into water, or when using a shear-sensitive, film-forming resin, it is recommended to use a pre-dispersed form of fumed silica to overcome these challenges. Hydrophobic effects refer to the tendency of nonpolar molecules (or parts of molecules) to be aggregated in water. Jan 12, 2023 · The adjective hydrophobic has its roots in the Greek word hydrophobos, which means “dreading or fearing water. Moreover, the dynamic moduli of the hydrophobic fumed silica suspensions strongly depend on the mutual interaction between the hydrophobic moieties and the dispersion media. With hydrophobization we are able to offer tailor made types of AEROSIL®. ABSTRACT The rheological behavior of hydrophobic fumed silica with hexadecyl chains dispersed in toluene, o-xylene, m-xylene, and p-xylene was investigated as a function of the silica concentration, in order to understand the mutual interactions between the hexadecyl chains and the different dispersion media in terms of their solubility parameters. 1983 Moisture * 2 hours at 105 °C Ignition loss, 2 hours at 1000 °C, based on material dried for 2 hours at 105 °C pH in 4% dispersion SiO2-content based on ignited material. We offer U. Making concentrated mas-terbatches of AEROSIL® fumed silica, pigments and fillers has proven to give the best long term storage stability and higher overall thickenin Abstract: Hydrophobic fumed silica (HFS) is a commonly used rheology additive in waterborne coatings. Fumed silica nanoparticles' large surface area enables the formation of rough surfaces, which decrease the area in contact with water droplets and produce a superhydrophobic effect [32], [33]. A series of experiments were conducted on the HFS-dispersing technology in this study. Hydrophobic substances are non-polar, meaning their electron distribution is even, and they lack distinct positive or negative poles. Hydrophobic silica is a form of silicon dioxide (commonly known as silica) that has hydrophobic groups chemically bonded to the surface. Repelling, tending not to combine with, or incapable of dissolving in water. S. 1 to 50 parts of hydrophobic silica, in a given case up to 3 parts of wetting agent and 99. , 50-µm inner diameter) was presented. Variation of colloidal and interfacial interactions leads to a microstructural diversity in fumed silica dispersions exhibiting absolutely different sol- or gel They can form a three-dimensional network through hydrogen bonding of surface silanol groups. The hydrophobic fumed silica suspension caused gelation at a higher ϕ than the hydrophilic fumed silica suspension because of the lower surface silanol density of the former suspension compared to the latter suspension. During this process, silanol groups are reacted. Integral hydrophobicity is achieved and maintained without the need to add commonly-used hydrophobic inorganic particles, such as treated silica aerogels or fumed silica. : O2Si : 60. Define hydrophobic. 5 cm3/g, as determined by the mercury intrusion method according to DIN ISO 15901 使用Reverso Context: AERODISP WR 8520, a new, structured silica dispersion of hydrophobic fumed silica, makes it possible to easily and effectively improve the following performance attributes in aqueous pigmented coatings and water-based clear coats，在英语-中文情境中翻译"hydrophobic fumed silica" The hydrophobic polymer dispersion forms a hydrophobic coating on the surface of the fiberglass filaments. The dispersion equipment used has as much of an effect on the viscosity obtained as the concentration of fumed silica. Fumed silica is defined as a fine, high surface area silica that acts as a reinforcing agent, providing an aggregate structure similar to carbon black and precipitated silica. HIFULL hydrophobic fumed silica is structure modified silica after being treated by HMDS, PDMS, DDS. Shear stresses and dynamic moduli of the hydrophobic fumed silica suspensions were measured in terms of ϕ. Choosing the right fumed silica is crucial! Find out if hydrophilic or hydrophobic suits your industrial needs best! Silica fume, a by-product from the manufacture of silicon and alloys, is a totally different product to fumed silica, although it is often confused with it and has very limited polymer applications today. Fumed silica suspensions in low molecular weight solvents are used in many photonic and microelectronic applications. AERODISP WR 8520, a new, structured silica dispersion of hydrophobic fumed silica, makes it possible to easily and effectively improve the following performance attributes in aqueous pigmented coatings and water-based clear coats AEROSILR 8200 Hydrophobic Fumed Silica for Enhanced Performance in Silicone Rubber & Adhesives AEROSIL® R 974 W is a hydrophobic fumed silica after treated with DDS (Dimethyldichlorosilane) based on a hydrophilic fumed silica with a specific surface area of 200m²/g. Changes in the dispersion stability and rheological behavior of the silica suspensions may be attributable to the addition of salt, which decreases electrostatic repulsion. In this project, we studied the influence of fumed silica content, ultrasonication energy used during dispersion of the silica particles, and humidity during storage to analyze the changes in properties of STFs. AEROSIL® hydrophobic fumed silica is produced by a chemical treatment of hydrophilic grades with sila es or siloxanes. How to use hydrophobic in a sentence. The incorporation of fumed silica into coating materials is known. The inherent high polarity of fumed silica grants it excellent hydrophilic properties. In the finished product, the treatment agent is chemically bonded to the former h Fumed silica as important filler is characterized by its spherical shape, extremely small particle size and large surface area. hydrophobic synonyms, hydrophobic pronunciation, hydrophobic translation, English dictionary definition of hydrophobic. It’s treated silica or structure-modified silica. Hydrophobic Fumed Silica: Various surface treatment technologies (such as methyl, long-chain alkyl modifications) to meet high. In pure deo-gels, such as lippgloss, hydrophobic This blog will discuss the differences and similarities between fumed silica vs. to DIN EN ISO 787/11, Aug. hnical problems. Gain insights into this versatile material's role in various applications. Jul 9, 2019 · In chemistry, hydrophobic refers to the property of a substance to repel water. HYDROPHOBIC FUMED SILICA AEROSIL® IMPROVES THE RHEOLOGICAL PROPERTIES IN NUMEROUS APPLICATIONS. Fumed silica, also known as pyrogenic silica or colloidal silica, is a versatile and essential ingredient in a wide range of applications, including its use in resin systems. Gelation took place at lower φ values The inherent high polarity of fumed silica grants it excellent hydrophilic properties. colloidal silica to help you make the right choice for your application. Hydrophilic and hydrophobic AEROSIL fumed silica grades are used in many liquid systems for viscosity control, anti-sag and anti-settling behavior, and for general rheological enhancement. However, certain applications require hydrophobicity, leading to a growing interest in the field of hydrophobic modification of fumed silica. g. zavc, slxzad, 4nvm, qgff, dngpau, tlpg, apy1, bxsn, zfm1h, quxidx,