Common inorganic fillers

Other additives that can be included in the pol5nneric material include dyes, inks, antioxidant. An antistatic characteristics is also be important for some applications. Many antistatic additives are compoimds with hydrophilic and hydrophobic sections. A common material of this type is a mono ester of a polyol, such as glycerol, with a long-chain fatty acid, such as stearic acid. In Table 10.1 some common inorganic fillers are listed. 

The quality of the spectra obtained in two minutes is more than adequate for qualitative identification. Differences in crystallinity are readily seen for both PP and polyester samples. Some common inorganic fillers such as glass and talc are weak Raman scatterers and are not evident in the spectra. In other cases inorganic fillers are seen, e.g., BaS04 in voided polyethylene terephthalate film. 

The mbber compound usually requires an inert inorganic filler and small particle sise carbon particle for reinforcement. The mbber polymers vary in inherent tensile strength from very high in the case of natural mbber to almost nonexistent for some synthetic polymers, eg, SBR. The fillers most commonly used for mbber compounds include carbon black, clay, calcium carbonate, siUca, talc (qv), and several other inorganic fillers. 

The addition—reaction product of bisphenol A [80-05-07] and glycidyl methacrylate [106-91-2] is a compromise between epoxy and methacrylate resins (245). This BSI—GMA resin polymerizes through a free-radical induced covalent bonding of methacrylate rather than the epoxide reaction of epoxy resins (246). Mineral fillers coated with a silane coupling agent, which bond the powdered inorganic fillers chemically to the resin matrix, are incorporated into BSI—GMA monomer diluted with other methacrylate monomers to make it less viscous (245). A second monomer commonly used to make composites is urethane dimethacrylate [69766-88-7]. 

Principles and Characteristics Mass-spectral analysis methods may be either indirect or direct. Indirect mass-spectral analysis usually requires some pretreatment (normally extraction and separation) of the material, to separate the organic additives from the polymers and inorganic fillers. The mass spectrometer is then used as a detector. Direct mass-spectrometric methods have to compete with separation techniques such as GC, LC and SFC that are more commonly used for quantitative analysis of polymer additives. The principal advantage of direct mass-spectrometric examination of compounded polymers (or their extracts) is speed of analysis. However, quite often more information can be... 

Crosslinked polymers are widely used as dental materials (1-31. Perhaps the most challenging application is in the restoration of teeth (4). The monomers must be non-toxic and capable of rapid polymerization in the presence of oxygen and water. The products should have properties comparable to tooth enamel and dentin and a service life of more than a few years. In current restorative materials such properties are sought using so-called "dental composites" which contain high volume fractions of particulate Inorganic fillers (5-71. However in the present article attention is concentrated on one commonly used crosslinked polymeric component, and on the way in which some of its properties are influenced by low volume fractions of fillers. 

Composites occur abundantly in nature, two of the most common being bone and wood. Bone is a very complex but well-ordered material with at least two levels of composite structure. The more fundamental of these two levels consists of an inorganic filler embedded... 

Silica powder, glass beads and fibres are commonly used for the reinforcement of plastics. The produced composite materials have an increased thermal and mechanical stability, compared to the pure polymeric material. In order to bind the inorganic filler to the organic matrix, silane molecules, with both an inorganic and organic side, are used. The silane may be mixed with the matrix and filler material in the composite preparation, or be coated onto the filler prior to mixing. The application... 

Diluents, although commonly presumed inert, do have the ability to influence the stability or bioavailability of the dosage form. For example, dibasic calcium phosphate (both anhydrous and dihydrate forms) is the most common inorganic salt used as a filler-binder for direct compression. It is particularly useful in vitamin products as a source of both calcium and phosphorous. Milled material is typically used in wet-granulated or roller-compacted formulations. The coarse-grade material is typically used in direct compression formulations. It is insoluble in water, but its surface is alkaline and it is therefore incompatible with drugs sensitive to alkaline pFI. Additionally, it may interfere with the absorption of tetracyclines [7]. 

Inorganic fillers such as clays, CaCC>3, talc, silica, titanates, A1 and asbestos are commonly used in epoxy adhesives, as they are cheap and readily available. Conducting epoxies can be formulated with powdered copper metal or a mixture of a blend of Sn-Pb-Bi. 

Inexpensive, finely ground minerals like barium sulfate (barytes), dolomite, limestone (whiting), clays, and silica are widely used to provide bulk and reduce the cost of friction material formulations. These materials also act as friction modifiers and alter the performance of the end product. Other less commonly used fillers are hollow and solid organic and inorganic microspheres and fly ash. 

Thermosets. Fire retardancy in thermosetting polymers is achieved largely by the use of reactive fire retardants because the common fire-retarding additives lack permanence. The flammability of thermosetting materials can be reduced by the additions of inorganic fillers and/or reactive flame retardant components. Flame-retardant vinyl monomers or other cross-linking agents are also frequently employed. 

Under the microscope, Biodac appears as small rocks attached to cellulose fibers and bundled into granules. Because of short cellulose fibers on the surface of Biodac , the filler provides a mechanical adhesion (interlocking) with the plastic matrix without any surface treatment. The thermal expansion-contraction coefficient of Biodac appears to be much closer to that of plastics, compared to the coefficients of common mineral fillers. Hence, the bond between Biodac and the plastic after weathering of the composite material becomes loose at lesser extent compared to inorganic fillers. 

Surfactants are used to control cell size and structure. The most common surfactants are siloxane-oxyalkylene copolymers, polyoxyethylene sorbitan fatty acid esters, and the condensation products of ethylene oxide with castor oil and alkyl phenols. A commonly added additive is urea which is used as a formaldehyde scavenger. Very fine particle size inorganic fillers can be added to act as nucleating sites and to promote finer, more uniform cell structure, as well as increased compressive strength, but at a cost of higher density. 

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