Fillers chemical composition

GENERAL PROPERTIES OF LIGNOCELLULOSIC FIBER AS FILLERS Chemical Composition... 

Filler Chemical Composition Specific Gravity (g/cm ) Surface Area (mVg) Mohs Hardness Specific. Heaf C (at298K)(J/g.K) Thermal Conductivity (W/m.K)... 

AWS) has issued specifications covering the various filler-metal systems and processes (2), eg, AWS A5.28 which appHes to low alloy steel filler metals for gas-shielded arc welding. A typical specification covers classification of relevant filler metals, chemical composition, mechanical properties, testing procedures, and matters related to manufacture, eg, packaging, identification, and dimensional tolerances. New specifications are issued occasionally, in addition to ca 30 estabUshed specifications. Filler-metal specifications are also issued by the ASME and the Department of Defense (DOD). These specifications are usually similar to the AWS specification, but should be specifically consulted where they apply. 

The properties of fillers which induence a given end use are many. The overall value of a filler is a complex function of intrinsic material characteristics, eg, tme density, melting point, crystal habit, and chemical composition and of process-dependent factors, eg, particle-si2e distribution, surface chemistry, purity, and bulk density. Fillers impart performance or economic value to the compositions of which they are part. These values, often called functional properties, vary according to the nature of the appHcation. A quantification of the functional properties per unit cost in many cases provides a vaUd criterion for filler comparison and selection. The following are summaries of key filler properties and values. 

Table 4. Chemical Composition Requirements for Aluminum and Magnesium Filler Metals ...

Ref 2. The brazing filler metal is analyzed for those specific elements for which values are shown. If the presence of other elements is the amount of those elements is deterrnined to ensure that the maximum total of each is <0.15 wt%. Remainder of material is Cu. Value represents maximum. Remainder of material is Mn. Table 7. Chemical Composition Requirements for Nickel and Cobalt Filler Metals indicated in the analysis. ... 

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]. 

Numerous filler characteristics influence the properties of composites [14,15]. Chemical composition and, in particular, purity of the filler both have a direct and an indirect effect on its application possibilities and performance. Traces of heavy-metal contamination decrease stability. Insufficient purity leads to discoloration, high purity CaC03 has the advantage of a white color, while the grey shade of talc filled composites excludes them from some fields of application. 

Spectroscopic techniques are extremely useful for the characterization of filler surfaces treated with surfactants or coupling agents in order to modify interactions in composites. Such an analysis makes possible the study of the chemical composition of the interlayer, the determination of surface coverage and possible coupling of the filler and the polymer. This is especially important in the case of reactive coupling, since, for example, the application of organofunctional silanes may lead to a complicated polysiloxane interlayer of chemically and physically bonded molecules [65]. The description of the principles of the techniques can be found elsewhere [15,66-68], only their application possibilities are discussed here. 

It is important to recognize that these correlations only apply to a specific polymer and, as discussed above, will be sensitive to changes in the polymer crystallinity, the inclusion of filler, and the exact chemical composition. The sensitivity of solubility in polydimethylsiloxane to the filler content has been noted (14 15) and the correlation in Table III for PDMS applies ony to the unfilled fluid. The crystallinity of many polymers depends on their molecular weight, and may change if the polymer is subject to biodegradation. The solubility parameter, i.e. the polarity, of polyurethanes, is sensitive to the nature and ratio of the ether (or ester) and urethane segments. 

In this experiment you will study a common physical property of solids, density. As you discovered in Chapter 7, the density of a polymer is dependent upon its chemical composition, the degree of crystallinity, and how it is processed. Adding fillers to a polymer will produce a composite with a density no doubt different from that of ... 

Talc is a hydrated magnesium silicate that is composed of thin platelets primarily white in color. Talc is useful for lowering the cost of the formulation with minimal effect on physical properties. Because of its platy structure and aspect ratio, these extenders are considered reinforcement. Polymers filled with platy talc exhibit higher stiffness, tensile strength, and creep resistance, at ambient as well as elevated temperatures, than do polymers filled with particulate fillers. Talc is inert to most chemical reagents and acids. The actual chemical composition for commercial talc varies and is highly dependent on the location of its mining site. 

The multitude of described fillers make it impossible to describe the properties of every one. Their application possibilities are not only dependent upon their chemical composition but also to a large extent upon their physical properties and their posttreatment, if any. Purity is an additional criterion, particularly in the case of natural fillers. 

The gas composition of smoke depends on the chemical composition, the molecular structure and polymer formulation of the burning material, which may include a variety of additives, plasticizers, stabilizers, flame retardants, cross-linking agents, fillers, and blowing agents. In addition, the conditions of... 

---