Precipitated silica

About: Precipitated silica is a research topic. Over the lifetime, 1401 publications have been published within this topic receiving 20992 citations.

Functionalized siloxy compound, silica reinforced rubber compositions thereof and tire with component comprised thereof

Abstract: The present invention relates to a functionalized siloxy compound which is useful in silica-filled rubber compositions and the processing of a sulfur curable rubber composition containing silica. Accordingly, the invention further relates to a rubber composition containing at least one diene-based elastomer, particulate synthetic amorphous silica (e.g. precipitated silica) and said functionalized siloxy compound as a coupling agent and to an article of manufacture (e.g. tire) containing a component comprised of such rubber composition.

Thermo Sensitivity of Polysiloxane/Silica Nanocomposites Affected by the Structure of Polymer-Filler Interface.

Abstract: In this work thermo sensitivity was investigated with the bound rubber theory and thermoelasticity theory of the polymer-filler interface interaction between Polymethylvinylsiloxane (PMVS) and nanofillers (fumed and precipitated silica with the primary particle size of 10 nanometres). Bound rubber (the transition phase between PMVS and silica) content was measured by sol-gel analysis and swelling experiments. Results showed that the amount of bound rubber increases steadily with the increases of filler content. But the increasing rate suddenly decreased at certain silica content (between 40 and 50 phr of precipitated silica and between 30 and 40 phr of fumed silica, respectively), which was constant with the thermoelaticity experiment results. The temperature coefficients in low strain uniaxial extension are found to present sudden changing at the same silica content. This observation shows that thermo sensitivity is closely connected with the structure of polymer-filler interface.

Structural analyses of the bound rubber in silica-filled silicone rubber nanocomposites reveal mechanisms of filler-rubber interaction

Abstract: Although the reinforcing effect of fumed silica on silicone rubber is always better than that of precipitated silica, their enhancement mechanism is still controversial due to the cognitive defects of the interface effect and filler network effect of polymer nanocomposites with the limited experimental study. Herein, significant entanglement network structure differences were revealed in the fumed and precipitated silica-filled phenyl silicone rubber by removing the physisorbed rubber gradually via 90 °C-ultrasonic solvent extraction method, which eventually obtained tightly bound rubber to explain filler-rubber interaction. The silica wrapped by tightly bound rubber was observed by SEM and TEM, where fumed silica is entangled with tightly bound rubber to robust dendritic structure, while precipitated silica is entangled with tightly bound rubber to the irregular agglomerate structure. Low-field 1H NMR confirmed that the mobility of the tightly bound rubber was significantly lower than loosely bound and free rubber. Furthermore, during the US treatment, the Si–O–Si infrared peaks of fumed silica-filled rubber exhibited "blueshift-redshift-blueshift" while the precipitated silica one only "blueshift" appears, which directly confirmed that different nanoporous structures of nanofiller induced diversity of filler-rubber entanglement network. The tightly bound rubber of precipitated silica (16.71%) was much more than that of fumed silica (3.72%) (40 phr). Although fumed silica adsorbs less tightly bound rubber than precipitated silica, the prominent nanofiller networks formed by fumed silica-rubber greatly enhanced the Payne effect and damping properties. This work can help to deeper understand the formation of the filler-rubber entanglement network and its contribution to the physical properties.

Surface modified silicas

Abstract: Finely divided silica e.g. diatomaceous earth, precipitated silica, silica aerogel and fume silica s surface modified by treating with a mixture of (1) a liquid cyclic siloxane, and (2) an organic silicon compound of general formula where R is an alkyl group of not more than 3 carbon atoms R1 and R11, which may be the same or different, are phenyl groups, alkyl or alkoxy groups containing not more than 3 carbon atoms; n is 0, 1, 2 or 3 and not more than two aryl groups are attached to any one silicon atom. The mixture, which may contain from 5% to 95% of the liquid cyclic siloxane, can be added to the silica, in an amount from 5% to 40% by weight of the silica, by any suitable method provided the treating medium is evenly distributed throughout the total bulk of the silica. The preferred method is to form the silica into a fluidized bed and introduce the mixture via an atomizer at a point well below the apparent surface of the bed usually at ambient temperature. The product is used as a filler for organopolysiloxane elastomers. The cyclic siloxanes (1) mentioned are octamethyl cyclo tetrasiloxane, decamethyl cyclo pentasiloxane, duodecamethyl cyclohexasiloxane and tetramethyl tetravinyl cyclo-tetrasiloxane, and the compounds (2) are exemplified as diphenyl dimethoxy silane, diphenyl-diethoxy silane, diphenyl di-n-propoxy silane, phenyl trimethoxy silane, phenyl methyl dimethoxy silane, dimethyl diphenyl dimethoxy disiloxane, diphenyl tetramethoxydisiloxane, and dimethyl triphenyltrimethoxy trisiloxane.ALSO:A filler for organo-polysiloxane elastomers is produced by treating finely divided silica (particle size not greater than 10 micron) with a mixture of (1) a liquid cyclic siloxane, and (2) an organic silicon compound of the general formula where R is an alkyl group of not more than 3 carbon atoms, R1 and R11, which may be the same or different, are phenyl groups, alkyl or alkoxy groups of not more than 3 carbon atoms; n is 0, 1, 2, or 3, and not more than two aryl groups are attached to one silicon atom. The cyclic siloxane is present in amounts of from 5 to 95%, preferably 40-60% by weight of the mixture and the silica is usually treated (see Group III) with from 5 to 40% preferably 10-25% of its own weight of the mixture. Samples of elastomer compositions were prepared by mixing various amounts of filler with 100 parts by weight of a linear methyl vinyl polysiloxane and one part of red iron oxide. The compositions can be stored, for periods up to eight weeks and after storing freshen easily to mix with 0,5 parts of dichlorbenzoyl peroxide and cure by pressing at 400 lbs. per square inch at 115 DEG C. for 10 mins. The compositions are then given a further heating in air.

Reinforcing compositions for thermoplastic polymers including a precipitated silica having improved properties of non-caking and flow

Abstract: Reinforcing agents for thermoplastics polymers comprising at least one impact additive and a pptd. silica in the form of agglomerates with an ave. size of 5-15 mu .