Showing papers on "Precipitated silica published in 2008"

Process for recovering heavy oil utilizing one or more membranes

Abstract: An oil recovery process utilizes one or more membranes to remove silica and/or oil from produced water. In one method, the process includes separating oil from produced water and precipitating silica. The produced water having the precipitated silica is directed to a membrane, such as a ceramic membrane, which removes the precipitated silica from the produced water. In some cases, residual oil is present and is also removed by the membrane.

Reinforcement of maleated natural rubber by precipitated silica

Abstract: Graft copolymers of maleic anhydride and natural rubber or so-called maleated natural rubbers (MNRs) were prepared in a molten state with varying maleic anhydride contents from 4 to 10 phr. In this work, the filler–filler and filler–rubber interactions of the MNR and precipitated silica were investigated. The MNR compounds containing 40 phr of silica both with and without 9 wt % of silane coupling agent were prepared. By increasing the maleic anhydride contents, the Mooney viscosity and cure times were increased, but the torque differences and cure rate indices were decreased. Bound rubber was increased with increasing maleic anhydride content, indicating an increase of filler–rubber interaction. In case of the compounds without silane, the MNR with 6 phr of maleic anhydride showed the lowest filler–filler interaction as indicated by a decrease of storage modulus upon an increase of strain in the filled compound i.e., Payne effect. This MNR compound also yielded the optimum mechanical properties. It has been demonstrated that a use of MNR with appropriate maleic anhydride content can reduce filler–filler interaction dramatically and hence improve a silica dispersion, as confirmed by SEM micrographs, resulting in an enhancement of the mechanical and dynamical properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Effect of fly ash silica and precipitated silica fillers on the viscosity, cure, and viscoelastic properties of natural rubber

Abstract: The viscosity, cure properties, storage, and loss moduli and tan δ of natural rubber (NR) filled with the same amounts of precipitated silica (PSi) and fly ash silica (FASi) fillers were measured. The fillers were treated with bis[3-triethoxysilylpropyl-]tetrasulfide (TESPT), or, used in the rubber untreated. TESPT is a sulfur-containing bi-functional organosilane that chemically adheres silica to rubber and also prevents silica from interfering with the reaction mechanism of sulfur cure. The dispersion of PSi and FASi in the rubber was investigated using scanning electron microscope (SEM). The effects of silica type and loading and surface treatment on the aforementioned properties were of interest. The SEM results showed that the FASi particles were larger in size and had a wider particle size distribution when compared with the PSi particles. The viscosity of the compounds decreased progressively with mixing time, and the compounds with FASi had a lower viscosity than those filled with PSi. The treatment with Si69 had no beneficial effect on the dispersion of the fillers in the rubber matrix. At low temperatures, the type and loading of the filler had no effect on the storage and loss moduli of the compounds, but the effect was more pronounced at high temperatures. There was also evidence from the tan δ and glass transition temperature (Tg) measurements that some limited interaction between the filler particles and rubber had occurred because of TESPT. Copyright © 2008 John Wiley & Sons, Ltd.

Filled Ethylene-propylene Diene Terpolymer Elastomer as ThermalInsulator for Case-bonded Solid Rocket Motors

Abstract: Ethylene-propylene diene terpolymer (EPDM)-based insulation system is being globallyused for case-bonded solid rocket motors. A study was undertaken using EPDM as base polymer,blended with hypalon and liquid EPDM and filled with fibrous and non-fibrous fillers. Theseformulations were evaluated as rocket motor insulation system. The basic objective of the studywas to develop an insulation system based on EPDM for case-bonded applications. A series ofrocket motor insulator compositions based on EPDM, filled with particulate and fibrous fillerslike precipitated silica, fumed silica, aramid, and carbon fibres have been studied for mechanical,rheological, thermal, and interface properties. Compositions based on particulate fillers wereoptimised for the filler content. Comparatively, fumed silica was found to be superior as fillerin terms of mechanical and interface properties. Addition of fibrous filler (5 parts) improved thepeel strength, and reduced the thermal conductivity and erosion rate. All the compositions wereevaluated for sulphur and peroxide curing. Superior mechanical properties were achieved forsulphur-cured products, whereas peroxide-cured products exhibited an excellent ageing resistance.Rocket motors were insulated with optimised composition and propellant cast, and the motorswere evaluated by conducting static test in end-burning mode. Defence Science Journal, 2008, 58(1), pp.94-102 , DOI : http://dx.doi.org/10.14429/dsj.58.1628

Effect of compatibilizer on the dispersion of untreated silica in a polypropylene matrix

Abstract: BACKGROUND: A new processing method for polypropylene-untreated precipitated silica (PP/SiO2) Composites based on the incorporation of a second polymer phase of polyamide 6 (PA6) is presented and compared with a more classic one making use of compatibilizers: glycerol monostearate (GMS), ethylene acrylic acid ionomer (IAAZE) and maleic anhydride grafted polypropylene (NIA-graft-PP). The effects of processing methods and conditions on the microstructure and properties Of PP/SiO2 Composites prepared by melt compounding are investigated with a view to reduce the size of aggregates of silica from the micrometre to the nanometre scale and to improve the link between filler and matrix. RESULTS: On the one hand, the presence of GMS and LAAZE compatibilizers significantly improves the dispersion of the silica particles. On the other hand, when using a PA6 second phase, the SiO2 particles are dispersed in PA6 nodules. Within these nodules, SiO2 appears dispersed at the nanoscale but with larger particles ('aggregates') of about 200 nm. Significant improvements in tensile strength and modulus are obtained using MA-graft-PP compatibilizer. An increase in impact strength is observed in the case of GMS compatibilizer. Thermal parameters indicate also that silica plays the role of nucleation agent for PP matrix. All improvements (tensile strength, modulus and impact strength) increase with the addition of compatibilized PA6 second phase. CONCLUSION: By the incorporation of masterbatch of silica in PA6 as a second polymer polar phase, a successful new production method for PP/SiO2 nanocomposites has been developed. Interestingly, this method does not require any (expensive) pre-treatment of the silica. (c) 2007 Society of Chemical Industry.

Comparing effects of silanized silica nanofiller on the crosslinking and mechanical properties of natural rubber and synthetic polyisoprene

Abstract: The effect of the same amount of precipitated silica nanofiller on the curing and mechanical properties of natural rubber and synthetic polyisoprene was investigated. The silica surfaces were pretreated with bis(3-triethoxysilylpropyl) tetrasulfide (TESPT) to chemically bond silica to rubber. The rubbers were primarily cured by using sulfur in TESPT, and the cure was optimized by the addition of accelerator and activator, which helped to form sulfur chemical bonds between the rubber and filler. Different amounts of accelerator and activator were needed to fully crosslink the filled rubbers. The hardness, tensile strength, elongation at break, stored energy density at break, tearing energy, and modulus of the vulcanizates improved substantially by the incorporation of the filler in the rubber. This was due to high level of rubber-filler adhesion and formation of chemical bonds between the rubber and TESPT. Interestingly, natural rubber benefited more from the filler than did synthetic polyisoprene. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Effect of the Filler Characteristics on the Miscibility of Styrene-Butadiene Rubber and Nitrile-Butadiene Rubber Blends

Abstract: Styrene-butadiene rubber (SBR) and nitrile-butadiene rubber (NBR) blends are immiscible. Fillers can be used as compatibilizers. The SBR + NBR blends reinforced with a mesoporous silica and a precipitated silica are characterized by studying their miscibility by the determination of rubber bound, their changes in heat capacity at each glass transition temperature, and their mechanical performance. NBR is preferentially located at the silica surface improving its dispersion. Larger rubber + filler as well as SBR + NBR interphases are obtained for the blends reinforced with the mesoporous silica, whose high surface area and organized porous structure allow a better polymer + filler interaction. The reinforced blends present higher strength at break than each reinforced polymer alone. The best performance is attained for blends reinforced with mesoporous silica. POLYM. ENG. SCI., 00:000–000, 2008. a 2008 Society of Plastics Engineers

Mechanism of silica reinforcement in CPE/NR blends by the use of rheological approaches

Abstract: Blends of elastomeric chlorinated polyethylene (CPE) and natural rubber (NR) at blend composition ratio of 80/20 CPE/NR with various precipitated silica loadings were prepared By the use of rheological approaches, a mechanism of silica reinforcement was proposed Results obtained reveal that the viscoelastic behavior of blends is influenced remarkably by loadings of silica A cure promotion phenomenon is found as silica is loaded due probably to the strong silica-CPE interaction and/or a reduction in curative absorption on silica surfaces A strong Payne effect is observed, which is increased by a rise in silica loading, implying a formation of pseudocrosslink via a physical interaction, which could be disrupted at high strain of deformation The proposed mechanism of silica reinforcement based on the formation of pseudocrosslink is validated by the deactivation of silanol groups on silica surfaces using silane-coupling agents The bis-(3-triethoxysilylpropyl) tetrasulfane (Si-69) is found to be more effective in suppressing the pseudocrosslink than 3-thiocyanatopropyl triethoxy silane (Si-264), which is thought to be the result of its larger amount of alkoxy groups at a given silane loading © 2007 Wiley Periodicals, Inc J Appl Polym Sci, 2008

Fly ash particles and precipitated silica as fillers in rubbers. III. Cure characteristics and mechanical and oil‐resistance properties of acrylonitrile‐butadiene rubber

Abstract: This study investigated the cure characteristics, mechanical properties, and oil resistance of acrylonitrile–butadiene rubber (NBR) filled with 60 phr carbon black (CB) and different amounts of silica from fly ash [fly ash silica (FASi)] and precipitated silica (PSi). Loadings of CB and PSi silica in NBR vulcanizates reduced the scorch and cure times. An increase in the cure time of FASi–CB–NBR vulcanizates was probably caused by an interaction between the polarity of NBR and the metal oxide activators in FASi, which could retard the curing. The tensile modulus of NBR vulcanizates increased with the addition of CB and silica fillers and with immersion in hydraulic oil at 125°C. CB exhibited a more pronounced effect on the NBR reinforcement versus the PSi and FASi fillers. The tensile and tear strengths and elongation at break decreased under thermal aging in hydraulic oil. The PSi system showed better reinforcement of CB–NBR vulcanizates than the FASi system. The hardness of NBR vulcanizates increased with CB and silica. The results in this work suggest that silica from fly ash particles could be used as an extender for cost savings in NBR compounds. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Effect of Plasma Polymerization on the Performance of Silica in NBR, EPDM and NBR/EPDM Blends

Abstract: The surface modification of precipitated silica powders by plasma-polymerization with acetylene monomer in order to improve their performance in NBR, EPDM and NBR/EPDM rubber blends, by matching the surface energies of the silica fillers of the rubbers, is the subject of this study. Silica, used as reinforcing filler for elastomers, is coated with a polyacetylene (PA) film and characterized by water penetration measurements, Cetyltrimethyl Ammonium Bromide (CTAB) area, Thermo Gravimetric Analysis (TGA), Time of Flight-Secondary Ion Mass Spectroscopy (ToF-SIMS) and Scanning Electron Microscopy with elemental analysis by Energy Dispersive X-ray spectroscopy (SEM/EDX). All techniques show the evidence of a PA-film deposition on the surface of silica. The properties of NBR, EPDM and blends based on NBR and EPDM, filled with untreated, PA- and silane-treated silica, are investigated by measurement of the Payne effect, the bound rubber content and weight loss related to bound rubber, the reinforcement ...

Release controlled particle comprising a biologically active substance, and preparing method thereof

Abstract: A release controlled particle for oral administration is provided to control the release of various active ingredients using biologically active ingredient-silica particles obtained by impregnating the active ingredient or the active ingredient together with a release delaying agent with a porous precipitated silica, thereby being applied to an orally administered formulation such as a fast disintegrating tablet, chewing tablet, capsule, general tablet and syrup. A release controlled particle for oral administration comprises: a core where a biologically active ingredient is impregnated with porous silica having an average particle diameter of 50-1,000 micrometers; and a polymer coating layer formed outside of the core, wherein the core further comprises a release delaying agent of the active ingredient. A method for preparing the release controlled particle comprises the steps of: (a) impregnating a solution prepared by dissolving the biologically active material in a solvent with the porous silica to prepare the core by mixing or kneading the solution of the biologically active material and the porous silica; and (b) coating the core with a coating solution including a solvent and the polymer material. Further, the polymer coating layer is single or multi coating layer.

Process for the preparation of finely divided precipitated silica

Abstract: The present invention provides a process for the preparation of finely divided precipitated silica. Finely divided precipitated silica is prepared by neutralization of alkali silicate solution, under continuous stirring, at 60° to 90° C. in presence of alkali metal salt as coagulating agent, in various neutralization steps during which neutralization is interrupted for specific time. Further acidic silica sol, is added until 60 to 80% of total alkali is neutralized. The reaction mixture is then aged at least for 3 minute under continuous agitation, followed by circulation through centrifugal pump at an appropriate rate.

Effects of Particle Size and Size Distribution on the Mechanical Properties of EPDM/Silica Vulcanizates

Abstract: In this work we present the influence of different particle size (surface areas: 120,150, 200 and 250 m2/g) and size distribution of precipitated silica on the mechanical properties of Ethylene- Propylene-Diene (EPDM) rubber. The vulcanization system employed was efficient. Compounds were prepared using a Banbury internal mixer. Tensile and tear properties of vulcanized blends were determined according to ASTM D412 and ASTM D624 procedures, respectively. Results show an increasing tendency on tensile properties when particle size decreases, due to the better dispersion of the filler and to a greater interaction with the rubber. Increases of up to 500% on tensile strength and 400% on tear strength were observed. However, there was an incoherent behavior for the silica with surface area of 200 m2/g (Si-200), so size distribution of the aggregates was experimentally determined by a microphotography study. Secondary aggregates size distribution was very different for each type of silica. Aggregates for Si-200 presented a bimodal distribution where the greater frequencies correspond to aggregates with surface area higher than the corresponding values for the Si-120. This fact could explain why the mechanical properties of the EPDM filled with Si-200 are not in between the values of the compounds filled with Si-150 and Si-250.

New Gel Coat Formulation

Abstract: New gel coat composition, in particular new marine gel coat compositions, a process for their manufacture as well as their use to coat surfaces of articles exposed to light, water and solvents. The gel coats incorporate a precipitated silica having - A BET surface of from 150 to 250 m 2 /g - A SiO 2 content of more than or equal to 98.5 % by weight - A Na 2 O content of less than or equal to 0.5 % by weight.

Method for preparing precipitated silica with boron sludge

Abstract: The invention discloses a method for preparing precipitated silicon dioxide by using boron slurry sludge; acid pickling boron slurry sludge is used for preparing the food-grade magnesium carbonate and obtaining secondary sludge; alkaline liquor is added into the secondary sludge and acid treatment is carried out to obtain silicic acid sol; finally, sodium silicate solution is added to precipitate silicon dioxide sediment The invention leads the conversion rate of the magnesium in the boron slurry to be more than or equal to 87 percent and the yield of the silicon dioxide to be 76 percent to 77 percent The method solves the comprehensive utilization problem of the silicon dioxide, which is not solved by the existing boron slurry comprehensive utilization technology, thus not only improving the comprehensive utilization rate of resources, but also solving the bad influence of the secondary boron slurry to environment fundamentally

Influence of Silanization on Dynamic-Mechanical Properties and the Distribution of Silica in NBR/BR Blends

Abstract: The influence of surface modification of precipitated silica by defined silanization on filler-rubber interaction and filler distribution in NBR/BR blends is investigated. A linear increase of the maximum value of the loss modulus in the glass trasnsition regime is not only caused by the increase in the volume fraction of the filler, but is also governed by the strength of the filler-matrix interaction. It is shown that with increasing phase bonding the extent of the dependence G"=f(Φ) rises and, due to the surface modification, the filler distribution, the dispersion and the dynamic-mechanical properties can be selectively influenced. The distribution of silica in the different phases of blends is estimated from the height of the loss modulus in the glass transition range.

Process for synthesizing nanosize silica particles

Abstract: A method for synthesizing nano-sized silica particles is provided to obtain silica having a particle size of 50-800nm. A method for synthesizing nano-sized silica particles comprises the following steps of adding sodium silicate is added to HCl of 0.1-0.3N so that pH can be within a range of 3-7, in the room temperature and precipitating silica gel; removing NaCl components by washing/filtering precipitated silica gel; and By using the bead mills, the silica gel from which the NaCl components is removed is pulverized at a pulverizing speed of 2000-6000rpm so as to become particles of nano size.

Silica-rubber mixes with improved strength properties

Abstract: FIELD: rubber industry. ^ SUBSTANCE: invention relates to inorganic extenders-containing elastomer compositions with improved strength properties and provides a method to increase strength of silica-diene rubber mixes, which method comprises mixing with indicated mix at least one organofunctional silane containing at least one alkoxy group per one silicon atom and strength-enhancing amount of at least one representative of the group consisting of thixotropic colloidal silica; precipitated silica; MQ resin wherein Q is SiO4/2 and M is R1R2R3SiO1/2, in which R1, R2, and R3 represent identical or different functional or non-functional organic groups; and carbon black. ^ EFFECT: increased strength of silica-rubber mixes. ^ 32 cl, 6 dwg, 20 ex

Self-Adhesive Silicone Compositions For Unpressurized Vulcanization

Abstract: Self-adhesive silicone elastomer compositions contain as ingredients: (A) at least one siloxane-containing polymer having organic radicals capable of crosslinking, (B) at least one treated or untreated, fumed or precipitated silica, (C) at least one silicate having thermally or hydrolytically cleavable leaving groups O—R 2 , which are silicate salts or low molecular weight silicate compounds, where R 2 is H, an organic radical, or, instead of O—R 2 , a halogen, (D) at least one resin forming monomer or oligomer with a linear structure, with the proviso that silicates are not included, (E) at least one suitable crosslinking system selected from the group containing peroxide-induced crosslinking or noble metal catalyzed addition crosslinking.

Precipitated silica with special surface characteristic

Abstract: PROBLEM TO BE SOLVED: To solve such problems that the thickeners used for RTV one-component system silicone rubber include silicas and in view of the sensitivity to hydrolysis of the silicone sealants, these silicas must introduce as little moisture as possible into the system, thus using fumed silicas almost exclusively to date for such application and besides, hydrophilic precipitated silicas have not been used to date on account of their high moisture content. SOLUTION: There are provided the precipitated silicas having an SiOH-isolated absorbance ratio equal to or greater than 1 and characterized in that its silanol group density is 0.5-3.5 SiOH/nm 2 . COPYRIGHT: (C)2008,JPO&INPIT

Modified Polymer with Partitioning Agent

Abstract: A modifier material and method for making the same is characterized by the addition of a partitioning agent to a polymer material such as synthetic rubber to prevent reagglomeration of the rubber. The partitioning agent reduces the time required to disperse the modifier material in a material to be modified and also reduces the viscosity of the modified material so that the modified material is easier to handle. The partitioning agent preferably includes a mixture of phenyl formaldehyde resin and precipitated silica gel.

Preparation of Precipitated Silica Powder from Iron Ore Tailing

Abstract: The preparation of precipitated silica particles via chemical precipitation using iron ore tailing and sodium hydroxide as raw materials was successfully demonstrated.The experimental conditions for synthesizing precipitated silica particles were examined in detail.The phase composition,morphology and structure of the synthesized particles were characterized by X-ray diffraction(XRD),FT-IR spectrometry,scanning electron microscopy(SEM),transmission electron microscopy(TEM),and X-ray fluorescence analysis.The SiO2 purity in the precipitated silica product was 92.3%,determined by X-ray fluorescence analysis.The chemical structure of precipitated silica was hydrated silicon oxide through FT-IR analysis.The structure of precipitated silica was amorphous by XRD analysis.The SEM and TEM micrographs showed that the shape of precipitated silica particles was nearly spherical,and their average grain diameter less than 150 nm.The measured results of chemical and physical properties of precipitated silica powder were obtained as followed:the specific surface area was 108 m2/g,pH in the 10% suspending liquid 5.5~6.0,and loss on ignition at 1000℃ was 6.16%.The product could be comparable with the requirements of HG/T 3061-1999 industrial product standard.

Non-slip material and construction method thereby

Abstract: A method for preparing an anti-slipping composition, and a method for constructing an anti-slipping bottom by using the composition are provided to allow it to be coated easily by using a roller or a trowel and to prevent the generation of dust. A method for preparing an anti-slipping composition comprises the steps of mixing 38-42 parts by weight of a bisphenol A type liquid epoxy resin, 4-4.5 parts by weight of texanol, 6-8 parts by weight of amorphous precipitated silica and 38-42 parts by weight of barium sulfate in a jacket at 60 deg.C; adding 2.2-6.32 parts by weight of a pigment and 5.7-6.6 parts by weight of a viscosity modifier to the mixture; adding 0.08-0.12 parts by weight of an antifoaming agent and 0.08-0.12 parts by weight of a coupling agent to the mixture to make a base; mixing the obtained base and a curing agent in a ratio of 5:1 by weight to make a resin composition; and mixing the obtained resin composition and any one anti-slipping agent selected from silica, alumina grit, copper slag and iron slag in a ratio of 1:1 by weight.

Materials for producing transparent heat protection elements and light protection elements produced using such materials and also processes for producing them

Abstract: A heat protection element having at least one support element and a protective layer is described. The protective layer is a water-containing silicate composition which can be obtained from alkali metal oxide and SiO 2 and contains at least one alkylsiloxane, where the alkyl groups are linear or branched C 1 -C 4 -alkyl groups. A preferred aqueous dispersion containing silicon dioxide, which is distinguished by containing the silicon dioxide in the form of precipitated silica and is stabilized by addition of polyol and alkali metal hydroxide, in particular potassium hydroxide, is likewise described. Such a dispersion is preferably solidified by addition of potassium hydroxide.

Modifikace siliky pro gumárenské směsi

Abstract: Precipitated silica is important filler, which is used in rubber compounds because it improves properties of vulcanizates. Modification (surface treatment) of silica can provide better dispersion of filler and further improve vulcanizate properties. This master thesis deals with modification of precipitated silica with alcohol, acid, oil and solvent. In theoretical part is described composition of rubber compounds, their preparation and modification of fillers. The practical part includes description of methods, devices and tests used in measuring. Main part includes results and discussion where is described influence of individual modification agents on properties of vulcanizates.

Rubber composition for tire comprising micro pearl type preciptated silica

Abstract: A rubber composition for a tire, and a tire containing the tire comprising the composition are provided to improve the dispersion of silica used as a reinforcing filler. A rubber composition for a tire comprises 20-80 parts by weight of micro-pearl type precipitated silica based on 100 parts by weight of a rubber material which comprises 10-90 wt% of an emulsion polymerization styrene-butadiene rubber comprising 30-50 wt% of styrene, 10-30 wt% of vinyl and 20-50 wt% of an aromatic oil, and 10-90 wt% of an emulsion polymerization styrene-butadiene rubber containing 15-40 wt%. Preferably the micro-pearl type precipitated silica has a length of 40-500 micrometers, a BET of 200-250 m^2/g and a pH of 6.5-8.5.

Preparation and Surface Modification of Precipitated Silica

Abstract: The silica was prepared by alcohol salt hydrolyzation precipitation method. Sodium dodecyl sulfonate(SDS)was selected out as surface modifier. The effects of SDS's dosage, concentration of modifier, time of modification, temperature of modification on modification were researched. The optimum process conditions are as follow: dosage of modifier 0.0010 mol/(10 g SiO2), concentration of modifier 0.06 mol/L, time of modification 80 min, and temperature of modification 80 ℃. Under these conditions, the degree of activation of product is 40.05%, settlement volume is 1.25 mL/g.