Mineral substrates coatings

Moreover, the stability constant for the higher affinity Pb(II)-humate complex (i.e., log Pb.S2) is 2.1 to 3.4 units larger than those of higher affinity mineral surface binding sites. Therefore, in the case of a mineral substrate coated by PAA or HA, it is possible that binding sites of PAA or HA will outcompete mineral surface binding sites. 

PEG hydrogenated castor oil binder, mineral substrate coatings... 

FIG. 15 Effect of lycopene on resorption of the calcium phosphate substrate coating of osteologic multitest slides in the presence of osteoclasts (Rao et al., 2003). (Lycopene I -Effect on osteoclasts Lycopene inhibits basal and parathyroid hormone-stimulated osteoclast formation and mineral resorption mediated by reactive oxygen species in ray bone marrow cultures. Reprint from Journal of Medicinal Food. 2003 6, pp. 69-78 by permission of Mary Ann Liebert, Inc., Publishers.)... 

Keywords silicone resin network, masonry protection, building material, natural stone impregnation, silicone coating of mineral substrates, structure-effect principle of trifunctional silicones... 

It is well known that organosilicon compounds do not become equally well attached to all mineral substrates. While silicates always readily lend themselves to coating with silane and polysiloxane [19-21], the same cannot always be said of calcium carbonate [19, 20]. Calcium carbonate (calcite), a widely used filler, is generally considered difficult to cover with silanes. Given the proven, good attachment of silicone resin to calcium carbonate fillers in silicone resin emulsion paints [2, 22], the question arises as to whether only higher polymeric siloxanes are able to form hydrophobic protective coatings on calcium carbonate. 

The paint samples were prepared from a high-grade silicone resin emulsion paint [48] with a binder ratio of 10 wt% styrene acrylate to 10 wt% silicone resin emulsion (both 50% solids). The coatings were applied to a mineral substrate and dried at room temperature. Part of each sample was etched for a few minutes in 10% nitric acid so that the organic polymer could be visualized better. 

Coating of problematic mineral substrates with silicone (calcite, gypsum hemihydrate) was tested by the dry method. To this end, 100 g samples of filler were treated with either 0.1 or 0.5 wt% silicone active ingredient and then mixed at high speed for at least 3 min so that the silicone would be adequately distributed. 

Table 1. Effectiveness of coating mineral substrates with silanes.

Templeton et al. (2002a) used a combination of Pb Lm-XAFS and pXANES spectroscopy and transmission electron microscopy to show that B. cepacia causes biomineralization of Pb(II) in the form of highly insoluble pyromorphite at ( ) concentrations well below supersaturation with respect to pyromorphite. The phosphate in these minimal medium experiments is though to be provided by B. cepacia, and the pyromorphite forms on the outer cell membrane of B. cepacia. These types of studies are beginning to provide unique information on how microbial biofilms affect metal sorption processes at mineral surfaces, which is essential for understanding the transport and bioavailability of toxic metal ions in natural systems where such biofilms exist. They are also allowing quantitative evaluation of the competition between NOM (or biofilms) and the mineral substrates they coat for metal ion binding. 

Simple dry-coating trials on mineral substrates afford a way of checking the ability of silicones to become attached to polar sur ces (see Sample preparation and analytical methods above). Calcium carbonate is so important here because it is the most commonly employed filler in facade-coating systems. The organosilicon compounds employed were a monomer (MTMO), a partially characterized MTMO oligomer, and the high polymer H-siloxane used in special commercial fillers for fire-fighting (Table 2). 

On account of their properties, silicate paints are used as weather-resistant and wash-resistant coatings on mineral substrates in both exterior and interior applications. Substrates include lime, lime cement, cement renders (mortar groups I, II, and III), concrete, sandy limestone, as well as old silicate or mineral coatings. Old lime coats should be removed completely, and gypsum substrates should be treated only... 

Paint strippers used to remove coatings from wood and mineral substrates may be either alkaline or based on organic solvents. 

The most important requirements and properties of exterior-use coatings on mineral substrates are the water permeability to water and water vapor and protection against carbon dioxide. 

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