Topic
Precipitated silica
About: Precipitated silica is a research topic. Over the lifetime, 1401 publications have been published within this topic receiving 20992 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: In three separate experiments, one using a bicarbonate buffered aqueous NaCl solution and two using natural seawater, the solubility of chemically pure X-ray amorphous precipitated silica decreased by approximately 20" after aging in contact with solution for several months.
31 citations
Journal Article•
TL;DR: In this article, the authors developed a new method of amorphous silica was prepared from rice husk ash by sol-gel method and extracted precipitated silica particles were characterized by Fourier transform infrared (FTIR), X-Ray diffraction and Optical microscopy techniques.
Abstract: Rice husk is a form of agricultural biomass that provides an abundant silicon source. Rice husks are widely burnt in agricultural fields in India because it is difficult to find other uses for them. Farmers burn rice hulls usually under incomplete combustion conditions to avoid accidental fires. The objective of this study was to develop a new method of amorphous silica was prepared from rice husk ash by sol - gel method. Initially received from Rice husk ash was calcined at 400 0 C, 500 0 C, 600 0 C and 700 0 C for 5 hrs to remove the volatiles in the sample and determine the amorphous structure of SiO 2 . Next, the thermally treated RHA was mixed with alkali solution to produce sodium silicate solution and precipitated silica was produced by the neutralization of sodium silicate solution. Rice Husks soaked in nitric acid produced the maximum amount of the sodium silicate solution and precipitated silica. Sodium oxide (Na 2 O) content and silica (SiO 2 ) content in the sodium silicate solution were also determined. Extracted precipitated silica particles were characterized by Fourier transform infrared (FTIR), X-Ray diffraction and Optical microscopy techniques. The chemical composition of silica was confirmed by FTIR and SEM with EDX.. Highly pure amorphous silica was derived from rice husk ash was confirmed by XRD pattern. The morphology of the obtained materials was analyzed by SEM. At optimized conditions, a nano sized highly pure silica was produced with a high reactivity and 99.9% amorphous in form. This economic technology as applied to waste material also provides many benefits to the local agro industry. Thus this paper may be providing a low cost and simple method to prepare functional materials. Keywords : Rice husk ash, Silica gel, Minerals, Amorphous material, Agricultural bio-waste
31 citations
01 Mar 1980
TL;DR: In this paper, a self-constructed laser-photosedimentometer was used to study the stability of well-dispersed Aerosil-hydrosols at different pH values.
Abstract: The stability of standardized, well-dispersed Aerosil-hydrosols at different pH values has been studied using a self-constructed laser-photosedimentometer. Their stability behavior is in approximate agreement with the classical theory of charge stabilization; this is contrary to the stability behavior of precipitated silica. The Aerosil-hydrosols are stable for several days at pH values above 3; they can be reproducibly flocculated with polyethylene glycols of molar mass 6000 and 40,000, even in the absence of electrolyte, when the sol concentration is sufficiently high. Reproducibility, however, necessitates a standardized mixing procedure of sol and polymer; this involves forming, prior to mixing, layers of hydrosol and polymer solution separated by a layer of dispersion medium. The same method of mixing was used for the determination of the adsorption isotherms. The affinity and the specific amount adsorbed rise with increasing molar mass. The laser-photosedimentometer provides suitable parameters for the characterization of the sedimentation behavior of the flocculated sols, i.e., the flocculation efficiency of the added polymers. Due to the good correlation of these parameters, it was possible, using additional rheology measurements, to identify the classical model of polymer bridging as the most likely mechanism for the destabilization. The following outline can be established from the correlation of the adsorption and stability data, using results from measurements at various concentrations of Aerosil and polymer. The general picture of flocculation can be subdivided into granular and structured flocculation; this classification arises from the distinct effects of added polymer, having different molar masses, on the stability of Aerosil-hydrosols of varying concentration. The degree of flocculation increases with growing surface coverage and molar mass from granular to structured flocculation, when the sol concentration is sufficiently high. At low sol concentrations there is a possibility of restabilization, starting when there is a detectable remaining concentration of polymer in solution; this point corresponds to nearly total surface coverage, due to the high affinity of polymer adsorption.
31 citations
Patent•
27 Aug 2010TL;DR: In this article, a pneumatic tire with an outer, running surface containing, circumferential tread comprised of a styrene/butadiene (SBR) rich rubber composition containing two SBR's with spaced apart glass transition temperatures (Tg's), one of which is a functionalized SBR with a functional group reactive with hydroxyl groups on a precipitated silica, together with a combination of at least three resins with spaced- apart softening points.
Abstract: This invention relates to a pneumatic tire with an outer, running surface containing, circumferential tread comprised of a styrene/butadiene (SBR) rich rubber composition containing two SBR's with spaced apart glass transition temperatures (Tg's), one of which is a functionalized SBR with a functional group reactive with hydroxyl groups on a precipitated silica, together with a combination of at least three resins with spaced apart softening points. The filler reinforcement is a combination of precipitated silica and specialized rubber reinforcing carbon black.
31 citations
TL;DR: In this paper, a study of 80/20 CPE/NR filled with various silica loadings was conducted, and their properties were determined, and it was found that cure properties are influenced significantly by the addition of precipitated silica.
Abstract: Blends of 80/20 CPE/NR filled with various silica loadings were prepared, and their properties were determined. It was found that cure properties are influenced significantly by the addition of precipitated silica. Scorch time and cure time decrease with increasing silica loading, which could be explained by the thermal history attributed to the shear heating in the blending stage. An increase in crosslink density as a function of silica loading is believed to be caused by a migration of curatives to the NR phase. In terms of phase morphology, with increasing silica loading, the NR dispersed phase size decreases due to the increase in compound viscosity and, thus, the shear stress available for efficient blending. An increase in silica loading also enhances resistance to oil due to the decrease in the NR dispersed phase size associated with the dilution effect, but gives no significant impact on thermal aging resistance. According to the change in damping peak height associated with the shift in Tg of the CPE phase, silica appears to preferentially migrate to the CPE phase due to the strong interaction between CPE and silanol groups of the silica surfaces. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2218–2224, 2005
31 citations