Topic
Precipitated silica
About: Precipitated silica is a research topic. Over the lifetime, 1401 publications have been published within this topic receiving 20992 citations.
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TL;DR: In this paper, the dynamic rheological properties of the resulting uncured materials are measured and are used to assess filler-filler networking, showing that composites containing PDMS-PI exhibit lower values of the dynamic storage modulus (G') than those observed in control samples prepared without copolymer additives.
Abstract: In the present work, precipitated silica, liquid polyisoprene, and PDMS-PI block copolymer are mixed in different formulations. The dynamic rheological properties of the resulting uncured materials are measured and are used lo assess filler-filler networking. In small-amplitude tests, composites containing PDMS-PI exhibit lower values of the dynamic storage modulus (G') than those observed in control samples prepared without copolymer additives. The control samples remain stable during several months of storage, while samples containing low molecular weight block copolymers show evidence of an aging process. The rheological manifestations of this aging include a pronounced decrease in small-amplitude G' with lime, accompanied by weakening amplitude-dependence of both G' and G. These suggest a progressive reduction of filler-filler interactions, presumably caused by the development of a block copolymer layer at the filler-polymer interface. The make-up of that interfacial region is investigated by means of magic-angle spinning solid-state 1 H NMR experiments carried out on bound polymer fractions that survive extraction in a good solvent. Spin-spin relaxation times and the intensities of the relaxation modes associated with these characteristic times are used to identify the proportion of both PDMS and polyisoprene among the segments strongly immobilized by close contact with the silica surface and among the rest of the bound (un-extracted) interfacial layer. The changes in mechanical properties are correlated not with the overall composition of the bound polymer fraction, but with the increase in PDMS segments in close contact with the filler surface.
2 citations
TL;DR: In this paper, two types of amorphous silica namely, precipitated silica and pyrogenic silica, were studied and the surfaces of such silica were modified with silane coupling agents such as 3.
Abstract: Two types of amorphous silica namely, the precipitated silica and the pyrogenic silica, were studied. The surfaces of such silica were modified with silane coupling agents such as 3‐aminopropyltriethoxysilane, N‐2‐(aminoethyl)‐3‐aminopropyltrimethoxysilane and 3‐ureidopropyltrimethoxysilane. Pigments were obtained by the adsorption of organic dyes, C.I. Reactive Blue 19 and C.I. Acid Green 16, onto the modified silica surface. Structural properties of the modified silica and the pigments obtained were evaluated using scanning electron microscopy, zeta potential analysis and particle size measurement techniques. Moreover, colour of the pigments obtained was evaluated using the CIE L *a*b* colour space system. The specific surface area of the pigment obtained was estimated using the BET method.
2 citations
01 Jan 1992
TL;DR: In this paper, the effect of precipitated silica on the properties and degradation of NR and EV copolymer blends was studied at different loadings at different timescales.
Abstract: Blends of NR and ethylene-vinylacetate copolymer (EVA), having different proportions of the components were prepared in an internal mixer and their vulcanizates evaluated for technological properties. The effect of precipitated silica on the properties and degradation of the blends was studied at different loadings
2 citations
Patent•
13 Mar 1997TL;DR: In this article, a mixture of at least one aqueous suspension of precipitated silica and latex is provided, which has a solids content of between 10 and 40% by weight and a viscosity lower than 4×10−2 Pa s at a shear of 50 s−1.
Abstract: An aqueous suspension is provided including a mixture of at least one aqueous suspension of precipitated silica and of at least one latex, in which the aqueous suspension of precipitated silica has a solids content of between 10 and 40% by weight, has a viscosity lower than 4×10−2 Pa s at a shear of 50 s−1 and, after centrifuging at 7500 revolutions per minute for 30 minutes, produces a supernatant containing more than 50% of the weight of the silica initially in suspension. This suspension can be employed in compositions based on an inorganic binder and in concrete compositions.
2 citations
Patent•
27 Jan 2011
TL;DR: In this paper, a method for producing finely powdered silica comprising forming a silica-containing solution formed by dissolving precipitated silica derived from a natural product in carbon dioxide was presented.
Abstract: PROBLEM TO BE SOLVED: To make silica made from a natural product occurring in nature still finer.SOLUTION: There is provided a method for producing finely powdered silica comprising forming a silica-containing solution formed by dissolving precipitated silica derived from a natural product in carbon dioxide in a silica-containing solution formation tank 23, compressing the silica-containing solution by means of a compressor 24, thereafter ejecting the compressed silica-containing solution through an ejection mechanism 25 to effect its rapid pressure reduction and expansion to thereby evaporate the carbon dioxide from the solution, and recovering the finely powdered silica in a finely powdered silica recovery tank 26.
2 citations