Talc compound

Talc, compounded with a little clay and some flux, is used in making steatite bodies for low-loss electrical insulation. 

Sch Schone, J., Kotter, L, Grellmann, W. Properties of polypropylene talc compounds with different talc particle size. J. of Plastics Technology 2 (2012) 230-251. 

Three dusting powders containing boric acid are included in the B.P.C., ue. Boric Talc, 5 per cent of boric acid and 10 per cent of starch in talc Compound Salicylic Acid Dusting Powder, 3 per cent of salicylic acid and 5 per cent of boric acid in talc and Compound Zinc Dusting Powder, containing 5 per cent boric acid, 25 per cent zinc oxide, 35 per cent starch and 35 per cent purified talc. Boric Acid and Starch Dusting Powder, containing 25 per cent of boric acid is official in the B. Vet,C,... 

Ferro-Char can also be used with glass-reinforced, or solid sphere, MgO, mica, and talc compounds. 

Studies of the shear viscosity of talc compounds [ 12,23,25,26] indicate that these compounds behave similarly to carbon black [24] and calcium carbonate [25]. Yield values are induced by volume loadings of 0.15 and higher (Fig. 2.13). Early studies determined yield values by extrapolation. The Osanaiye et al. sandwich rheometer [21], later upgraded by Kim and... 

A 20 wt% talc masterbatch was prepared using an intermeshing and co-rotating twin-screw extruder with a screw diameter of 30 mm (Werner Pfleiderer ZSK-30, L/D 38 1). The HDPE was then dry-blended with the talc masterbatch in a one-to-one ratio, to produce HDPE/talc compounds with talc content of 10 wt%. 

The void fraction was used to characterize the foam samples. The foam density was determined by the water displacement method (ASTM D792-00). Samples were taken from regions near the gate, at the center, and near the end of the injection-molded part. The expansion ratio O is equal to the ratio of the bulk density of HDPE/talc compounds, po, to the measured density of the foam sample, Pf. The void fraction was calculated as follows ... 

Interaction of Solids With Flotation Reagents. For flotation to occur with the aid of reagents, such compounds must adsorb at the sohd—hquid interface unless the soHd to be floated is naturally hydrophobic. In this latter case only depression can be attempted by the use of additional ions or depressants that hinder bubble—particle adhesion. Frothers (typically long-chain alcohols) and/or modifying agents such as hydrocarbon oils can, however, be used to enhance the collection of naturally hydrophobic soflds such as M0S2, talc, or plastics. 

Various other soft materials without the layer—lattice stmcture are used as soHd lubricants (58), eg, basic white lead or lead carbonate [598-63-0] used in thread compounds, lime [1305-78-8] as a carrier in wire drawing, talc [14807-96-6] and bentonite [1302-78-9] as fillers for grease for cable pulling, and zinc oxide [1314-13-2] in high load capacity greases. Graphite fluoride is effective as a thin-film lubricant up to 400°C and is especially useful with a suitable binder such as polyimide varnish (59). Boric acid has been shown to have promise as a self-replenishing soHd composite (60). 

Polypropylene polymers are typically modified with ethylene to obtain desirable properties for specific applications. Specifically, ethylene—propylene mbbers are introduced as a discrete phase in heterophasic copolymers to improve toughness and low temperature impact resistance (see Elastomers, ETHYLENE-PROPYLENE rubber). This is done by sequential polymerisation of homopolymer polypropylene and ethylene—propylene mbber in a multistage reactor process or by the extmsion compounding of ethylene—propylene mbber with a homopolymer. Addition of high density polyethylene, by polymerisation or compounding, is sometimes used to reduce stress whitening. In all cases, a superior balance of properties is obtained when the sise of the discrete mbber phase is approximately one micrometer. Examples of these polymers and their properties are shown in Table 2. Mineral fillers, such as talc or calcium carbonate, can be added to polypropylene to increase stiffness and high temperature properties, as shown in Table 3. 

Aluminum compounds, particularly the hydroxides and oxides are very versatile. Properties range from a hardness iadicative of sapphire and comndum to a softness similar to that of talc [14807-96-6] and from iuertness to marked reactivity. Aluminas that flow and filter like sand may be used for chromatography (qv) others are viscous, thick, unfilterable, and even thixotropic (1). 

Sheet form, composed of organic roofing felt, saturated with asphalt and coating on both sides with asphalt compound that may or may not contain mineral stabiHzer, surfaced with powdered talc, mica, or other tine mineral matter to prevent sticking. Classified, in mineral net mass per unit area of roofing, as Type I, 1943 g/m (39.8 lb/100 fC) Type II, 2666 g/m (54.6 lb/100 fC) Type III, 2495 g/m (51.1 lb/100 fC) and Type IV, 1943 g/m (39.8 Ib/lOOfC). 

The mbber compound usually requires an inert inorganic filler and small particle sise carbon particle for reinforcement. The mbber polymers vary in inherent tensile strength from very high in the case of natural mbber to almost nonexistent for some synthetic polymers, eg, SBR. The fillers most commonly used for mbber compounds include carbon black, clay, calcium carbonate, siUca, talc (qv), and several other inorganic fillers. 

Miscellaneous. Talc is used in gypsumboatd joint compounds as a high end filler to promote smoothness, sandabiHty, and sag resistance. It is used in automotive primers and polyester body repair compounds to promote sandabiHty. It is used in a wide variety of caulking compounds to improve theology and sag resistance. 

Mineral fillers are used for light-colored compounds. Talc has a small particle size and is a semireinforcing filler. It reduces air permeabihty and has htde effect on cure systems. Calcined clay is used for halobutyl stoppers in pharmaceutical appHcations. Nonreinforcing fillers, such as calcium carbonate and titanium dioxide, have large particle sizes and are added to reduce cost and viscosity. Hydrated siUcas give dry, stiff compounds, and their acidity reduces cure rate hence, their content should be minimized. 

Large amounts of iaert fillers, such as whiting, talc, and clays, can be added. Very dense fillers, such as barium or strontium sulfates, are used to make compounds intended for sound-deadening appHcations. In contrast, high levels of reinforcing fillers, such as carbon black, produce undesirable properties ia the final product. 

Cera.mic, The ceramic substrate is made from a mixture of siUcon dioxide, talc, and kaolin to make the compound cordierite [12182-53-5]. Cordierite possesses a very low coefficient of thermal expansion and is thermal-shock resistant. The manufacturing process involves extmding the starting mixture (which is mixed with water and kneaded into a sort of dough) through a complex die to form the honeycomb stmcture. The extmded piece is dried and fired in a kiln to form the cordierite. The outside or circumferential dimension is formed by the die, and the length is cut later with a ceramic saw. 

Particulate fillers are divided into two types, inert fillers and reinforcing fillers. The term inert filler is something of a misnomer as many properties may be affected by incorporation of such a filler. For example, in a plasticised PVC compound the addition of an inert filler will reduce die swell on extrusion, increase modulus and hardness, may provide a white base for colouring, improve electrical insulation properties and reduce tackiness. Inert fillers will also usually substantially reduce the cost of the compound. Amongst the fillers used are calcium carbonates, china clay, talc, and barium sulphate. For normal uses such fillers should be quite insoluble in any liquids with which the polymer compound is liable to come into contact. 

F.8 Determine the empirical formula of each of the following compounds from the data given, (a) Talc (used in talcum powder) has mass composition 19.2% Mg, 29.6% Si, 42.2%... 

Silicates (compounds made up of silicon, oxygen and one or more metals with or without hydrogen. Asbestos dust is the most hazardous (page 55). Others, e.g. talc, mica, vermiculite, have caused a silicatosis on prolonged exposure.)... 

Solid disinfectants (disinfectant powders) usually consist of a disinfectant substance diluted by an inert powder. For example phenolic substances adsorbed onto kieselguhr form the basis of many disinfectant powders, while another widely used powder of respectable antiquity is hypochlorite powder. Disinfectant or antiseptic powders for use in medicine include substances such as acrifiavine, or antifungal compounds such as zinc undecenoate or salicylic acid mixed with talc. 

Phyllosilicates, in addition to talc and silica, have recently been evaluated for their use as tableting excipients. These compounds include the smectites, pa-lygorskites, and sepiolites [85a]. Although they show some promise, current levels of metallic impurities are currently too high for use in pharmaceutical preparations. 

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