Fillers, active powdered

Another study that concerned the use of an activated rubber crumb was also performed by Adov and co-workers [43]. They introduced a finely ground activated polychloroprene powder into a virgin chloroprene compound and made a quantitative assessment of the Payne effect in the vulcanisate. They produced data that showed the dependence of the real and imaginary parts of the dynamic shear modulus, and the dependence of the mechanical loss tangent on the logarithm of the strain amplitude for vulcanisates containing different contents of activated powder. Their results indicated that the introduction of the activated chloroprene powder into the vulcanisate promoted an improvement in the interaction of the rubber with the filler present in the compound, which should lead to an increase in the level of service properties for the products and open up a route for the effective re-use of the rubber waste. 

The main purpose of pesticide formulation is to manufacture a product that has optimum biological efficiency, is convenient to use, and minimizes environmental impacts. The active ingredients are mixed with solvents, adjuvants (boosters), and fillers as necessary to achieve the desired formulation. The types of formulations include wettable powders, soluble concentrates, emulsion concentrates, oil-in-water emulsions, suspension concentrates, suspoemulsions, water-dispersible granules, dry granules, and controlled release, in which the active ingredient is released into the environment from a polymeric carrier, binder, absorbent, or encapsulant at a slow and effective rate. The formulation steps may generate air emissions, liquid effluents, and solid wastes. 

All commercial materials are based on calcium hydroxide and liquid alkyl salicylates (Prosser, Grolfman Wilson, 1982) and are supplied as a two-paste pack. Zinc oxide is sometimes added to the calcium hydroxide, as are neutral fillers. A paste is formed from this powder by the addition of a plasticizer examples include A-ethyl toluenesulphonamide (o- orp-) and paraffin oil, with sometimes minor additions of polypropylene glycol. The other paste is based on an alkyl salicylate as the active constituent containing an inorganic filler such as titanium dioxide, calcium sulphate, calcium tungstate or barium sulphate. Alkyl salicylates used include methyl salicylate, isobutyl salicylate, and 1-methyl trimethylene disalicylate. An example of one commercial material, Dycal, is given in Table 9.7, but its composition has been subjected to change over the years. 

Nonmetal electrodes are most often fabricated by pressing or rolling of the solid in the form of fine powder. For mechanical integrity of the electrodes, binders are added to the active mass. For higher electronic conductivity of the electrode and a better current distribution, conducting fillers are added (carbon black, graphite, metal powders). Electrodes of this type are porous and have a relatively high specific surface area. The porosity facilitates access of dissolved reactants (H+ or OH ions and others) to the inner electrode layers. 

Coconut shell is the source of two other products, coconut shell flour and activated charcoal. Powdered coconut shell is used in the plastics industry as a compound filler for synthetic resin glues. It is also used as a filler and extender of phenolic molding powders that give a smooth and lustrous finish to molded articles, thereby improving their resistance to moisture and heat. Activated charcoal is an adsorbent for toxic agents. It has been used in gas masks, but can also be used to remove odors and industrial stench. As well, this by-product is a contact catalyst used to facilitate some industrial chemical reactions (61). 

The excipients used are fillers, but the most important are lubricants, such as magnesium stearate, PEG 6000, calcium stearate, glycerol palmito stearate, and calcium behenate, which increase the flowability but at the same time modify the hydrophobic characteristics of powders. Their choice depends on compatibility with active ingredient and the flow properties of powders. The characteristics of the excipient have been described previously. 

Powdered cellulose is used as a tablet diluent and a hard gelatin capsule filler see Table I. In both contexts it acts as a bulking agent to increase the physical size of the dosage form for formulations containing a small amount of active substance. 

With metallocene catalysts, not only homopolymers such as polyethylene or polypropylene can be synthesized but also many kinds of copolymers and elastomers, copolymers of cyclic olefins, polyolefin covered metal powders and inorganic fillers, oligomeric optically active hydrocarbons [20-25]. In addition, metallocene complexes represent a new class of catalysts for the cyclopolymerization of 1,5- and 1,6-dienes [26]. The enantio-selective cyclopolymerization of 1,5-hexadiene yields an optically active polymer whose chirality derives from its main chain stereochemistry. 

The type of movement required for mixing particulate matter also produces ideal conditions for agglomeration by coalescence. Therefore, unwanted agglomeration is often observed in powder mixers, especially if the particle size of the solids is small and/or a small amount of moisture is present. Considerable problems can arise if components of the bulk mass have different particle sizes because, in that case, the smaller fractions may selectively agglomerate, thus making it impossible to obtain an ideal mixture. Such selective agglomeration is of particular concern in the pharmaceutical industry where an extremely small amount of a finely divided active substance must often be mixed uniformly and reliably with a relatively large amount of inert filler material. 

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