Precipitated silica

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

Precipitated silica used as reinforcing filler for elastomers

Abstract: The invention concerns a novel method for preparing precipitated silica used as reinforcing filler for elastomers. It also concerns novel silica precipitates in the form of powder, granules or, preferably, substantially spherical balls, said silica being characterised in that they contain: a BET specific surface area ranging between 185 and 250 m2/g; a CTAB specific surface area ranging between 180 and 240 m2/g; a porous distribution such that the porous volume V2 consisting of pores with diameter ranging between 175 and 275 A represents less than 50 % of the porous volume V1 consisting of pores with diameter not more than 400 A; a porous volume (V?d1?) consisting of pores with diameter less than 1 νm more than 1.65 cm?3?/g; a fineness number (I.F) between 70 and 100 A; a fines contents (τ?f?) after ultrasound disintegration, of at least 50 %.

Morphology of Highly Dispersing Precipitated Silica: Impact of Drying and Sonication

Abstract: Light and X-ray scattering are used to examine the structure of two commercial precipitated silicas (Zeosil 1165 and Ultrasil 7005) and one developmental precipitated silica, Dimosil 288 All three products have a four-level hierarchical structure consisting of primary particles, aggregates, hard agglomerates and soft agglomerates, with Dimosil 288 showing the clearest evidence of the four structural levels The impact of sonication and drying protocol was explored by light scattering for Dimosil 288 With the exception of the large-scale soft agglomerates, all the structural levels are robust under sonication of aqueous suspensions Sonication breaks down soft agglomerates leaving hard structures approximately 11 μm in radius-of-gyration Drying plays a critical role in hardening the soft agglomerates If the product is never dried, sonication reduces the agglomerate size to 35 μm, which is identified as the size of the hard agglomerate Although agglomerates larger than 35 μm are present in the never-dried product, they are friable Large-scale agglomerates are marginally more robust when dried at 150 °C compared to room temperature drying Given the similarity of mechanical properties of rubbers filled with these silicas, it appears that the four-level structure with friable large-scale soft agglomerates is a characteristic of highly dispersing silica products

Investigation of Precipitation of Calcium Carbonate at High Supersaturations

Abstract: The formation mechanism of precipitated calcium carbonate from aqueous solution under industrial conditions (high supersaturation) was investigated in a semi-batch and in a continuous mixing nozzle process. The influence of potassium hydroxide and magnesium chloride on crystal modification and particle size were investigated in both processes. Rheological properties of the magnesium stabilized amorphous gel structure have been measured. A similarity between the formation process of calcium carbonate and precipitated silica has been proven.

Infrared evidence for two isolated silanol species on activated silicas

Abstract: Infrared spectroscopy has been used to study the OH stretching vibration of isolated silanol groups on an aerosil and a precipitated silica which have been activated under vacuum at 450, 600 or 800°C. When the 450°C activated samples are cooled to −191°C, the normally asymmetric OH peak splits into two components having a peak maximum near 3750 or 3746 cm −1 for the aerosil and precipitated silica, respectively, and a shoulder near 3738 cm −1

Interaction between Carboxylated Nitrile Rubber and Precipitated Silica: Role of (3-Aminopropyl)Triethoxysilane

Abstract: On the basis of measurements of bound rubber and physical properties and the results of Monsanto rheometer, dynamic mechanical and infrared spectroscopic studies, it is observed that strong rubber-filler interaction occurs between XNBR and precipitated silica filler. During molding, XNBR was found to be crosslinked by the filler surface through the formation of primary bonds. The coupling agent, namely (3-aminopropyl)triethoxysilane facilitates the formation of rubber-filler bonds at the expense of filler-filler networks, leading to improved dispersion and enhanced degree of crosslinking.