Filler definition

There is a definite trend in the suppHer industry to develop multifimctional materials with value-added properties. One suppHer has introduced a modified hydrocarbon resin that softens, improves filler incorporation, improves mill banding, and increases tack in the green compound while imparting increased low strain (<100%) stiffness, significantly improving tear resistance in the vulcanized compound. 

It should be noted that this is quite an unusual law, since in other known cases durability of solids is expressed by stronger laws, namely, exponential or power laws. Thus, in the given example we cannot give a unified definition of yield stress. The work cited is the only published observation of the durability of a filler s structure in dispersion systems. Therefore at present it is difficult to say how much such phenomena are typical for filled polymers, but we cannot exclude them. 

The term filler is fairly broad to denote quite a variety of substances. Usually, the term means solid substances added to polymers in relatively large quantities, i.e. 5% of mass. Such a definition does not include substances used in low concentrations ... 

Infrared spectroscopy is a major tool for polymer and rubber identification [11,12]. Infrared analysis usually suffices for identification of the plastic material provided absence of complications by interferences from heavy loadings of additives, such as pigments or fillers. As additives can impede the unambiguous assignment of a plastic, it is frequently necessary to separate the plastic from the additives. For example, heavily plasticised PVC may contain up to 60% of a plasticiser, which needs to be removed prior to attempted identification of the polymer. Also an ester plasticiser contained in a nitrile rubber may obscure identification of the polymer. Because typical rubber compounds only contain some 50% polymer direct FUR analysis rarely provides a definitive answer. It is usually necessary first... 

Conventional rubber compound analysis requires several instrumental techniques, in addition to considerable pretreatment of the sample to isolate classes of components, before these selected tests can be definitive. Table 2.5 lists some general analytical tools. Spectroscopic methods such as FTIR and NMR often encounter difficulties in the analysis of vulcanised rubbers since they are insoluble and usually contain many kinds of additives such as a curing agent, plasticisers, stabilisers and fillers. Pyrolysis is advantageous for the practical analysis of insoluble polymeric materials. 

In principle, any type of sample can be analysed by SEC provided that it can be solubilised and that there are no enthalpic interactions between sample and packing material. By definition then, this technique cannot be carried out on vulcanisates and even unvulcanised fully compounded rubber samples can present problems due to filler-rubber interactions. The primary use of SEC is to determine the whole MWD of polymers and the various averages (number, viscosity, weight, z-average) based on a calibration curve and to allow qualitative comparisons of different samples. Many commercial polymers have a broad MWD leading to strong peak overlap in the chromatography of complex multicomponent systems. 

An enormous variety of solvates associated with many different kinds of compounds is reported in the literature. In most cases this aspect of the structure deserved little attention as it had no effect on other properties of the compound under investigation. Suitable examples include a dihydrate of a diphosphabieyclo[3.3.1]nonane derivative 29), benzene and chloroform solvates of crown ether complexes with alkyl-ammonium ions 30 54>, and acetonitrile (Fig. 4) and toluene (Fig. 5) solvates of organo-metallic derivatives of cyclotetraphosphazene 31. In most of these structures the solvent entities are rather loosely held in the lattice (as is reflected in relatively high thermal parameters of the corresponding atoms), and are classified as solvent of crystallization or a space filler 31a). However, if the geometric definition set at the outset is used to describe clathrates as crystalline solids in which guest molecules... 

The degree of moisture present affects the properties of the silicone rubber vulcanisate. Moisture levels also determine the ease with which the filler is incorporated into the silicone rubber. Low moisture levels improve the final physical properties but definitely detract from the incorporation speed of the silica filler. 

Note 1 The term as defined here is specific to polymer science. An alternative definition of filler applies in some other fields of chemistry [3]. 

According to the ASTM definition, fillers are relatively inert, while reinforcements improve the properties of the materials to which they are added. Actually, few fillers that do not improve properties are used, but reinforcing fibers produce dramatic improvements to the physical properties of the material to which it is added, generally to form composites. 

In general, the filler industry recognises these limitations, and tries to use a few relatively simple parameters that, taken in combination, give an approximate, working definition of morphology appropriate to the application in mind. The parameters that are most likely to be encountered are specific surface area, average particle size, effective top size and oil adsorption. The measurement and application of these are discussed in more detail below. 

The value of Q is obtained from the plot of /2(X - X-2) versus and extrapolating to = 0. By comparison with the theory of elasticity, it has been proposed that Q = V2 NRT, where N is cross-link density, R the gas constant and T absolute temperature (of the measurement). When carbon black or other fillers are added to the elastomer, the prediction of the cross-link density is less definitive. 

The close fit of the experimental data and the values predicted by the constitutive modified Halpin-Tsai equations I and II (24) and (25), as seen in Fig. 43 (for NR) illustrates the appropriate definition of the IAF. Table 10 also confirms that newly devised equations (24) and (25) provide astounding results because their predictions conform to the experimental data. The introduction of IAF imparts a definitive change to the predicting ability of the constitutive equations for polymer/filler nanocomposites (Fig. 43 Table 10). 

A coarse grayish-green talc rock has been called soapstone or steatite and was formerly much used for stoves, sinks, electrical switchboards, etc, Talc finds use as a cosmetic, for lubricants and as a filler in paper manufacturing. Most tailor s chalk consists of talc. The origin of the word talc is not definitely known. 

The filler composition of the mastic is generally a mixture of many materials, each one employed with a definite objective. The compositions of these materials vary with the source of supply therefore, physical constants are difficult to compare. All materials are classified in this paper with respect to the properties in attaining a fire-resistant coating based on the theories disclosed. 

The proportionality constant Nf in Eq. (21) is a generalized Flory-Number of order one (Np=l) that considers a possible interpenetrating of neighboring clusters [22]. For an estimation of cluster size in dependence of filler concentration we take into account that the solid fraction of fractal CCA-clusters fulfils a scaling law similar to Eq. (14). It follow directly from the definition of the mass fractal dimension df given by NA=( /d)df, which implies... 

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