Diluents calcium carbonate

The polysulfide base material contains 50—80% of the polyfunctional mercaptan, which is a clear, amber, sympy Hquid polymer with a viscosity at 25°C of 35, 000 Pa-s(= cP), an average mol wt of 4000, a pH range of 6—8, and a ntild, characteristic mercaptan odor. Fillers are added to extend, reinforce, harden, and color the base. They may iaclude siUca, calcium sulfate, ziac oxide, ziac sulfide [1314-98-3] alumina, titanium dioxide [13463-67-7] and calcium carbonate. The high shear strength of the Hquid polymer makes the compositions difficult to mix. The addition of limited amounts of diluents improves the mix without reduciag the set-mbber characteristics unduly, eg, dibutyl phthalate [84-74-2], tricresyl phosphate [1330-78-5], and tributyl citrate [77-94-1]. 

By way of an early example, the effect of calcium carbonate, ATH, and MH fillers on smoke production from styrene butadiene (SBR) foams has been reported.47 It was evident that all the fillers reduced soot formation relative to unfilled foam with the hydrated fillers being more effective than the calcium carbonate, which was considered to act merely as matrix diluent. ATH and MH were found to give enhanced char formation with the promotion of solid-state cross-linking as opposed to pyrolytic degradation. An afterglow effect, occurring after the extinction of the flame, was noted with MH and attributed to the slow combustion of carbon residues. 

Bioavailability of triamterene has been studied in healthy human subjects.59 62 65 79 The bioavailability of triamterene was found to be 52%, corresponding to absorption of 83%, in a study done in six volunteers after intravenous administration of the drug.62 Another study reported that triamterene bioavailability from capsules was poorer and more variable than that from suspension.65 Effect of various vehicles and vehicle volumes on oral bioavailability of triamterene has been investigated.80 Addition of a combination of a surfactant and carbonate or bicarbonate as diluents to a triamterene gelatin capsule is reported to result in better bioavailability of the drug.81 When both calcium carbonate and cetylpyridinium chloride were present in a triamterene capsule the dissolution rates were greatly increased over triamterene capsules containing neither diluent or either... 

Calcium carbonate, calcium sulfate, kaolin, talc, magnesium carbonate, and zinc oxide are frequently used as nutrient supplements or food diluents. Calcium silicate and fumed silica are used as anticaking agents. They are added in concen-... 

Precipitated calcium carbonate Pure CaCOs prepared by chemical processes (see chapter on limestone, lime manufacturing and products) is preferred to gypsum as diluent in pharmaceuticals. 

Additives used in final products Plasticizers/flexibilizers epoxidized oils, low molecular polyamides, polysulfidesdibutyl phthalate, condensation products of adipic acid and glycols, isodecyl pelargonate, cyclohexyl pyr-rolidone Other diluents (glycide ether), modifiers, rheological additives, flame retardants Antistatics alkyl dipolyoxyethylene ethyl ammonium ethyl sulfate, carbon black, carbon monofiber, graphite, quaternary ammonium compound, silver-coated basalt, tin oxide Release calcium carbonate, carnauba wax, ceramic microspheres, ethylene bis stearoformamide, montan wax, silicone oil Slip carbon fiber, PTFE, sorbitan tristearate ... 

Manufacture of HGC dosage forms compared with tablets requires minimum formulation efforts and usually involves granulation of the API powders with diluents such as lactose, mannitol, calcium carbonate, and lubricants such as magnesium stearate. Prior to filling the capsules with the granulated API powder, the body and cap are separated. The cap is replaced after completion of the filling... 

Raw limestone is used to produce whiting (ground limestone) as an economical diluent filler in rubber compounding. It is also used as a feedstock to manufacture precipitated calcium carbonate, which is also used as a little more costly, but better, filler for extending a rubber formulation. 

Calcium carbonate is another inexpensive filler used in rubber compounding as an economic diluent. 

Most talcs and diy-groimd calcium carbonates are degrading fillers beeause of their large particles size, although the planar shape of the talc particles eontributes some improvement in reinforcement potential. The soft elays would fall into a class of diluent fillers that do not eontribute reinforeement, yet are not so large that they degrade properties. 

This is the economical filler par excellence, in ground, air floated and precipitated forms. It is used mainly as a diluent filler, although suitably treated precipitated types have a certain reinforcing effect. Because calcium carbonate is attacked by acids, even weak acids, its use should be avoided in compounds where the finished product could be in contact with these chemicals. 

Patel et al. [40] found that moismre and the pH of the micro-environment influenced degradation the most. They identified the best diluent for tablet manufacture as being dibasic calcium phosphate, with a basic modifier (sodium carbonate, sodium bicarbonate or magnesium oxide). The authors indicated that the degradation pathways observed were deiodination, deamination and decarboxylation. The data are shown in Table 2.4. 

The straight-chain 1- and 2-butenes are preheated to 600°C in a furnace, mixed with steam as a diluent to minimize carbon formation, and passed through a 5-m-diameter reactor with a bed of iron oxide pellets (or calcium nickel phosphate) 90 to 120 cm deep (contact time 0.2 second) at 620 to 750°C. The material is cooled and purified by fractional distillation and extraction with solvents such as furfural, acetonitrile, dimethylformamide (DMF), and N-mcthyIpyro11idonc (NMP) (Fig. 2). 

Tablet diluent Inert substance used as filler to create desired bulk, flow properties, and compression characteristics in preparation of tablets Dibasic calcium phosphate, kaolin, lactose, mannitol, microcrystalline cellulose, powdered cellulose, precipitated calcim carbonate, sorbitol, starch...

Chem. Desaip. Calcium sulfonate/carbonate complex in oil and wax diluent... 

A reverse microemulsion synthesis of CaCOa was reported later by Roman et al [339] who used xylene, a diluent oil (100-150 NS grade), 70% active sulfonic acid, calcium hydroxide and methanol the water content was evidently very small. Carbon dioxide was bubbled through the system the conversion was almost total within 0.5h. Water and methanol were separated by distillation. The particle size of the carbonates was around 1.5-3.0 nm. 

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