Fillers, preparation

The Teflon filler was obtained as a latex kindly supplied by the E. I. du Pont de Nemours Co. It had a much larger particle size than the fillers prepared in this laboratory, the latter having been designed to fall in the particle size range 400-600 A. However, it was still of interest to study the effect of the Teflon filler in view of the low rubber-filler interfacial adhesion that could be expected. 

Code 321. [Van Den Bmgh Foods] Hydrogenate soybean oil shortening for filler, prepared foods, spray oiL... 

Wood-filled PVC has inferior mechanical properties because of lack of interaction. Treatment of wood filler with aminosilane improves acid-base interaction between filler and polymer to the extent that impact strength and tensile properties of composite are improved over unfilled PVC. Tensile properties of PVC were deteriorated when leather particles were used as a filler. But, after filler particles were treated with ethylene-vinyl acetate copolymer, a coating was produced on the surface of filler particles that promoted adhesion with PVC and improved mechanical properties.These are some recent examples of many applications of filler preparations to improve its interaction with PVC. 

Kar Karger-Kocsis, J., Erdelyi, S., Nagy, G. Polyurea/vinylester hybrid thermoset resins with in situ produced silicate filler Preparation and static mechanical properties. J. Appl. Polym. Sci. 103 (2007) 853-859. 

Molding compound n. Granules or pellets of a resin containing all desired additives such as plasticizes, stabilizers, colorants, processing aids, and fillers, prepared by blending these ingredients with the neat resin, then reducing the hot mix to pellets by... 

Suzuki, N. Kiba, S. Kamachi, Y. Miyamoto, N. Yamauchi, Y., Mesoporous Silica as Smart Inorganic Filler Preparation of Robust Silicone Rubber with Low Thermal Expansion Property. J. Mater. Chem. 2011,21,5338-5344. 

Fillers are also used in the preparation of paper to improve the properties of the material and are added to bituminous materials such as plastics and road surfacing materials. 

Furfural has been used as a component in many resin appHcations, most of them thermosetting. A comprehensive review of the patent Hterature describing these uses is beyond the scope of this review. A few, selected recent patents and journal articles have been referenced. Resins prepared from the condensation products of furfural with urea (47), formaldehyde (48), phenols (49,50), etc, modified by appropriate binders and fillers are described in the technical Hterature for earlier appHcations, see reference 1, which contains many references in an appendix. 

Eor some appHcations the powder is suspended in an aqueous medium or a solvent with the help of emulsifying agents and then sprayed onto the substrate. The powder is also used as a filler to prepare sprayable compositions of PTEE dispersions, which then can be used to coat various substrates (36). 

Synthetic Marble. Synthetic marble-like resin products are prepared by casting or molding a highly filled monomer mixture or monomer—polymer symp. When only one smooth surface is required, a continuous casting process using only one endless stainless steel belt can be used (52,53). Typically on the order of 60 wt % inorganic filler is used. The inorganic fillers, such as aluminum hydroxide, calcium carbonate, etc, are selected on the basis of cost, and such properties as the translucence, chemical and water resistance, and ease of subsequent fabrication (54,55). 

Manufacture of friction elements includes the impregnation of fabrics and subsequent lamination, the wet-dough process, and the dry-mix process. Elements from the last two are prepared by compression-molding the formulation for up to an hour at 150—175°C. Thick brake elements require a carefully controUed heating-and-cooHng cycle to minimize stresses created by expansion and contraction (see Brake linings and clutch facings Fillers). 

Gibbsite is aii important technical product and world production, predominantly by the Bayer process, is more than 50 million metric tons aimuaHy. Alost (90%) is calcined to alumina [1344-28-1 j, Al202, to be used for aluminum production. Tlie remainder is used by the chemical industry as filler for paper, plastics, rubber, and as the starting material for the preparation of various aluminum compounds, alumina ceramics, refractories, polishing products, catalysts, and catalyst supports. 

Extra-Fine Precipitated Hydroxide. Very fine (< 1 /im-diameter) particle size hydroxide is produced by precipitation under carefully controlled conditions using specially prepared hydroxide seed. Precipitation is usually carried out at low (30 —40°C) temperatures causing massive nucleation of fine, uniform hydroxide particles (Fig. 5). Tray or tumiel Ape dry ers are used to dry the thorouglily washed filter cake to a granular product wliich is easily pulverized to obtain the fine hydroxide. Alternatively, the washed product is spray dried. Precipitation from an organic-free aluniinate Hquor, such as that obtained from the soda—sinter process, fields a very wliite product. Tlie fine precipitated hydroxide is used by the paper and plastic industries as fillers. 

It is common practice in the siHcone mbber industry to prepare specific or custom mixtures of polymer, fillers, and cure catalysts for particular appHcations. The number of potential combinations is enormous. In general, the mixture is selected to achieve some special operating or processing requirement, and the formulations are classified accordingly. Table 6 Hsts some of the commercially important types. 

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