Lubricants stearic acid

This optimization method, which represents the mathematical techniques, is an extension of the classic method and was the first, to our knowledge, to be applied to a pharmaceutical formulation and processing problem. Fonner et al. [15] chose to apply this method to a tablet formulation and to consider two independent variables. The active ingredient, phenylpropanolamine HC1, was kept at a constant level, and the levels of disintegrant (corn starch) and lubricant (stearic acid) were selected as the independent variables, X and Xj. The dependent variables include tablet hardness, friability, volume, in vitro release rate, and urinary excretion rate in human subjects. 

Preparation of Specimens for Mechanical Measurements. The specimens for mechanical testing were obtained by blending the powdered polymer with 1.5 phr of Ba-Cd stabilizer, 5 phr of CaC03, and 0.5 phr or lubricant (stearic acid). The dry blend was processed in a roll mill at 200°C for 5 minutes. The 1-mm sheets obtained were preheated in an oven at 200°C for 5 minutes and molded in a molding press at a pressure of 80-100 kg/cm2. The specimens were obtained by milling with suitable equipment. 

Fillers have been studied for their effect on the rheological properties of aminoplasts. Investigations of the rheological properties of aminoplasts filled with cellulose diacetate (CDA) wastes and into the effect of minor quantities of plasticizers on the viscosity of compositions have been carried out [12]. With a CDA content increase from 40 to 60% the viscosity of the composition declines. With the introduction into the aminoplasts of a lubricant (stearic acid) containing 50% CDA the viscosity of the compositions also declines. The same is observed when introducing 1-2% of plasticizer (unsaturated PEF). 

Stabilizer 9-A [Givaudan-Roure] Mono and diisoi pyiated m- and p- cresols antioxidant for fatty acids and their derivs. used in andstats, fiber lubricants, stearic acid, olek acid, vegetabie and animal oils, paraffin. 

PVC (medium to high molecular weight) plasticizers (most fi-equently phthalates) fillers (most fi equently ealcium carbonate) lubricants (stearic acid and stearates are the most popular) thermal stabilizers (metal soaps dominate)... 

It is necessary to be able to identify and quantify the additives in polymers and vibrational spectroscopy is a particularly useful approach to this problem. Compared with traditional chemical analyses, vibrational methods are nondestructive and are time-and cost-effective as well as more precise. A large number of examples exist in the literature. For example, antistatic agents (polyethylene glycol (PEG) in polyethylene (PE)) can be detected directly using FTIR sampling (367). An IR spectroscopic technique for the analysis of stabilisers (2, 6-di-tert-butyM-methylphenol) in PE and ethylene-vinyl acetate (EVA) copolymer has been described (368). It is possible to quantify the amount of external and internal lubricants (stearic acid in polystyrene (PS)) (371). Fillers in polymers can also be analysed (white rice husk ash (predominantly silica in polypropylene (PP)) (268). Raman spectroscopy has been used to detect residual monomer in solid polymethyl methacrylate (PMMA) samples (326). 

G. Keramik F. c6ramique The production of c. needs auxiliaries. Depending on the various technologies used in this industry, there are applications of RR-based products as plasticizers and lubricants (- stearic acid and their - metallic soaps, - oleic acid and - glycerol), deflocculants (mainly -+oleic acid, but also - stearic acid, - tartaric acid), - surfactants and foam depressants (steara-tes,-4metallic soaps,- fatty alcohols). 

Lithium hydroxide with 12-hydroxy-stearic acid (or hydrogenated castor oil) they form the family of lithium greases very commonly used for general lubrication and bearing lubrication. 

Sodium hydroxide with stearic acid they constitute the sodium greases, used in the lubrication of bearings under dry conditions and gear trains. 

It is known that even condensed films must have surface diffusional mobility Rideal and Tadayon [64] found that stearic acid films transferred from one surface to another by a process that seemed to involve surface diffusion to the occasional points of contact between the solids. Such transfer, of course, is observed in actual friction experiments in that an uncoated rider quickly acquires a layer of boundary lubricant from the surface over which it is passed [46]. However, there is little quantitative information available about actual surface diffusion coefficients. One value that may be relevant is that of Ross and Good [65] for butane on Spheron 6, which, for a monolayer, was about 5 x 10 cm /sec. If the average junction is about 10 cm in size, this would also be about the average distance that a film molecule would have to migrate, and the time required would be about 10 sec. This rate of Junctions passing each other corresponds to a sliding speed of 100 cm/sec so that the usual speeds of 0.01 cm/sec should not be too fast for pressurized film formation. See Ref. 62 for a study of another mechanism for surface mobility, that of evaporative hopping. 

Other constituents may be added to assist in the formation of uniform beads or to influence the use properties of the polymers through plasticization or cross-linking. These include lubricants, such as lauryl or cetyl alcohol and stearic acid, and cross-linking monomers such as di- or trivinylbenzene, diaHyl esters of dibasic acids, and glycol dimethacrylates. 

Dry lubricants are usually added to the powder in order to decrease the friction effects. The more common lubricants include zinc stearate [557-05-17, lithium stearate [4485-12-5] calcium stearate [1592-23-0] stearic acid [57-11-4] paraffin, graphite, and molybdenum disulfide [1317-33-5]. Lubricants are generally added to the powder in a dry state in amounts of 0.25—1.0 wt % of the metal powder. Some lubricants are added by drying and screening a slurry of powder and lubricant. In some instances, lubricants are appHed in Hquid form to the die wall. 

Individual particle surfaces can be lubricated by an adsorbed film that produces a smoother surface and/or decreases interparticle attraction. A plasticized binder may serve this purpose. Forming surfaces can be lubricated by coating with a film of low viscosity Hquid such as water or oil. Die surfaces can also be coated with a solution of stearic acid dissolved in a volatile Hquid that rapidly evaporates to leave a lubricating film. 

In Britain calcium stearate has been most commonly used with nontransparent products and stearic acid with transparent compounds. In the United States normal lead stearate, which melts during processing and lubricates like wax, is commonly employed. Dibasic lead stearate, which does not melt, lubricates like graphite and improves flow properties, is also used. 

Other additives that may be incorporated include sodium hydrogen phosphates as buffering agents to stabilise that pH of the reaction medium, lauryl mercaptan or trichlorethylene as chain transfer agents to control molecular weight, a lubricant such as stearic acid and small amounts of an emulsifier such as sodium lauryl sulphate. 

Stearic acid and metal stearates such as calcium stearate are generally used as lubricants at a rate of about 1-3% on the total compound. Waxes such as camauba and ceresin or oils such as castor oil may also be used for this purpose. 

Stearic acid is the most common of the long-chain fatty acids. It is found in many foods, such as beef fat and cocoa butter. It is widely used as a lubricant in soaps, cosmetics, food packaging, deodorant sticks, and toothpastes. It is also a commonly used softener in rubber. 

The most commonly used amphiphiles to build L-B hlms for tribological applications are the straight chain hydrocarbon compounds with simple functional groups such as the fatty acids, including stearic acids, arachidic acids, and behenic acids [32], but other amphiphilic molecules, e.g., 2,4-heneicosanedione and 2-docosylamina-5-nitropyridine, are also applied in some cases. There are two major systems of self-assembled monolayers, namely the alkylsilance derivatives (e.g., OTS, octadecyltrichlorosilane) on hydroxylated surfaces and the alkanethiols on metal substrates, which have been investigated extensively to examine their properties as solid lubricants and protective surface films [31 ]. 

Pellets or tablets (1.5-10 mm in diameter), rings (6-20 mm) and multichanneled pellets (20-40 mm in diameter and 10-20 mm high) are used when a high mechanical strength is required. They are produced by compressing a mixture of the support powder and several binders (kaolin day, stearic acid) and lubricants (graphite) in a press. 

An analytical solution for molecules with alkaline functionality is acid/base titration. In this technique, the polymer is dissolved, but not precipitated prior to analysis. In this way, the additive, even if polymer-bound, is still in solution and titratable. This principle has also been applied for the determination of 0.01 % stearic acid and sodium stearate in SBR solutions. The polymer was diluted with toluene/absolute ethanol mixed solvent and stearic acid was determined by titration with 0.1 M ethanolic NaOH solution to the m-cresol purple endpoint similarly, sodium stearate was titrated with 0.05 M ethanolic HC1 solution [83]. Also long-chain acid lubricants (e.g. stearic acid) in acrylic polyesters were quantitatively determined by titration of the extract. 

Some of the more common antifrictional agents are listed in Table 10. Many of these are hydrophobic and may consequently affect the release of medicament. Therefore, lubricant concentration and mixing time should be kept to the absolute minimum. Lubricants may also reduce significantly the mechanical strength of the tablet (see Fig. 12) [29,81]. Stearic acid and its magnesium and calcium salts are widely used, but the... 

Lubricants such as magnesium stearate and stearic acid are also required. These facilitate the passage of the filling ring under the foot of the powder hopper... 

The most effective lubricants are the hydrophobic stearates, such as magnesium stearate, calcium stearate, and stearic acid. Magnesium stearate is the most widely used lubricant [117,118]. Lubricants proposed as being less hydrophobic such as hydrogenated vegetable oils, polyethylene glycols, and sodium stearyl fumarate are less effective in this application [118]. 

Lubricants Improve processibility Stearic acid Paraffin waxes PE waxes... 

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