Hydrated sodium silicate particles can be expanded by heat to form thin-walled bubbles that can be broken, neutralized, washed and dried to provide hydrated silica flakes. These flakes can be mixed with non-swelling sorptive particles such as TLC grade silica and used to make chromatographic articles. One such article is a composite of a poly(tetrafluoroethylene) fibril matrix in which those particles and hydrated or fired silica flakes are enmeshed. The hydrated silica flakes can be fired to a refractory state and then incorporated into protective coatings to enhance their resistance to abrasion while also better protecting the coated substrates from corrosion.
The invention provides a planar chromatographic plate comprising a supported homogeneous thin porous film of ceramic material produced by sol-gel technology the film being provided with a porous network enabling elution through the film whereby planar chromatographic separation of chemicals or biochemicals can be carried out therewith.
Effect pigments having improved optical properties based on SiO.sub.2 flakes coated with one or more layers, where the SiO.sub.2 flakes have a thickness of from 50 nm to 150 nm; processes for the preparation thereof; and use of these pigments in cosmetics, paints, coatings, plastics, films, in security printing, in security features in documents and identity cards, for coloring seed, for coloring foods or in medicament coatings and for the preparation of pigment compositions and dry preparations; are disclosed.
A surface coating composition comprising, in combination, a fibrillated polymer matrix, at least one pigment, at least one binder, and at least one solvent, and a method for the manufacture thereof.
A method for isolating an environmentally hazardous organic contaminant from a fluid utilizes a solid phase extraction medium comprises a PTFE fibril matrix, and sorptive particles enmeshed in said matrix comprising more than 30 and up to 100 weight percent of porous organic particles, and less than 70 to 0 weight percent of porous (organic-coated or uncoated) inorganic particles, the ratio of sorptive particles to PTFE being in the range of 40:1 to 1:4 by weight. The extraction medium is useful in pesticide, phenolics, and residue of explosives separations. The separations can be efficiently performed in a stacked disk format.
A composite article having controlled void volume and mean pore size comprises: (a) polytetrafluoroethylene (PTFE) fibril matrix, and (b) insoluble, non-swellable sorptive particles enmeshed in said matrix, the ratio of non-swellable sorptive particles to PTFE is in the range of 40:1 to 1:4 by weight, the composite article having a porosity in the range of 30 to 80 percent void volume and a mean pore size in the range of 0.3 to 5 micrometers, preferably with at least 90 percent of pores having a size less than 3.6 micrometers. The article is prepared by incorporating lubricant in the precursor admixture in an amount sufficient to exceed the lubricant sorptive capacity of the particles by at least 3 weight percent and up to an amount at which the mass loses its integrity.
