Stearates functions

Octyl stearate, function as ingredient in cosmetics, 7 829t... 

Typical strongly external lubricants are paraffin wax, polyethylene wax, oxidised polyethylene wax and stearic acid. Typical strongly internal lubricants are glycerol esters and fatty acids. Calcium stearate functions somewhere between internal and external, depending on addition level. It also acts as an acid scavenger. 

Metal soaps, mainly stearates, function as external lubricants, since they possess low affinity to all polymers. 

Standards for dmg chemicals are pubUshed ia USP—NE. Dmg substances are chemicals that have therapeutic or diagnostic uses, whereas pharmaceutical iagredients provide preservative action, fiavoiing, or hilfillment of a function ia the formulation of dosage-form dmgs. Examples of dmg substances are acetaminophen [103-90-2] ampicillin [69-53-4] aspirin [50-78-2] powdered ipecac, riboflavin [83-88-5] staimous fluoride [7783-47-3] and thyroid. Examples of pharmaceutical iagredients are ethylparaben [120-47-8] lactose [63-42-3] magnesium stearate [557-04-0] sodium hydroxide [1310-73-2] starch [9005-25-8] and vanillin [121-33-5],... 

Lubricants. Lubricants are used to improve the melt flow, screw feeding, and mold release of nylons. Long-chain acids, esters, and amides are used together with metal salts, eg, metal stearates. Improved melt flow is mainly a function of molecular weight reduction during mol ding. Mold release is improved by waxes of limited compatibiHty with nylon, which migrate to and lubricate the mold surface. 

Therapeutic Function Antibacterial Chemical Name Erythromycin stearate Common Name -... 

X-ray diffraction has been applied to spread monolayers as reviewed by Dutta [67] and Als-Nielsen et al. [68], The structure of heneicosanoic acid on Cu and Ca containing subphases as a function of pH has been reported [69], as well as a detailed study of the ordered phases of behenic acid [70], along with many other smdies. Langmuir-Blod-gett films have also been studied by x-ray diffraction. Some recent studies include LB film structure just after transfer [71], variations in the structure of cadmium stearate LB films with temperature [72], and characterization of the structure of cadmium arachidate LB films [73], X-ray [74,75] and neutron reflectivity [76,77] data on LB films can be used to model the density profile normal to the interface and to obtain values of layer thickness and roughness. 

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. 

Infrared measurement of additive concentrations is a more complex analysis than initially expected, as some additives may undergo a variety of chemical reactions during processing, as shown by Reeder et al. [128] for the FTIR analysis of phosphites in polyolefins. Some further examples of IR work refer to PVC/metal stearates [129], and PE/Santonox R [68,130]. Klingbeil [131] has examined the decomposition of various organic peroxyesters (TBPB, TBPP, TBPA and TBPO) and a peroxidicarbonate (BOPD) as a function of pressure, temperature and solvent by means of quantitative FTIR using an optical high p, T reaction cell. 

Fig. 12 Tensile strength of calcium sulfate tablets as a function of magnesium stearate concentration (solid fraction = 0.57). (From Ref. 29.)...

Surfactants. The use of surfactants is greatly restricted in formulating ophthalmic solutions. The order of surfactant toxicity is anionic > cationic >> nonionic. Several nonionic surfactants are used in relatively low concentrations to aid in dispersing steroids in suspensions and to achieve or to improve solution clarity. Those principally used are the sorbitan ether esters of oleic acid (Polysorbate or Tween 20 and 80), polymers of oxyethylated octyl phenol (Tyloxapol), and polyoxyl 40 stearate. The lowest concentration possible is used to perform the desired function. Their effect on preservative efficacy and their possible binding by macromolecules must be taken into account, as well as their effect on ocular irritation. The use of surfactants as cosolvents for an ophthalmic solution of chloramphenicol has been described [271]. This com-... 

Dampproofing admixtures are formulated to affect the properties of the hardened concrete, and not those of concrete in its plastic state. In the case of materials based solely on calcium and aluminum stearates, stearic acid in solid or emulsion form, bitumens and hydrocarbon resins, there will be no effect on the properties of the plastic concrete with regard to air content, workability, mix design parameters, etc. When water-reducing admixtures or accelerators are included in the formulation, the effect on the concrete will be a function of the particular type of material used (see relevant section). The wax emulsions do appear to have an effect on the properties of the plastic concrete because of the lubrication effect of the very small... 

Figure 8. The effect of reaction temperature on ethyl stearate conversion as a function of time-on-stream and Arrhenius plot (based on zero order kinetics) Reaction conditions 5 mol% ethyl stearate in hexadecane, mcat=0.4 g, p27o-c=l bar, P3oo"c=3 bar, p33ox=5 bar, p36o-c=7 bar and V =0.1 ml/min.

One very common beneficial interaction involving an excipient is the interaction between magnesium stearate and the metal of tablet punches and dies, or the equivalent parts on a powder encapsulation machine. Magnesium stearate is an example of a boundary lubricant. As such it has a polar head and a fatty acid tail. It is believed that the polar head of the magnesium stearate is oriented toward the die wall or tablet punch face. In these ways it is able to reduce the ejection force (the force required to eject the tablet from the die after compaction) and prevent sticking to the punch faces. The other boundary lubricants, e.g., calcium stearate and sodium stearyl fumarate, will also function in a similar manner. However, the so-called liquid film lubricants function in a very different manner (19). 

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