Fillers fundamental characteristics

As we consider the mechanical properties of SPs, it is often useful to consider them in the context of entanglements, which are intermolecular interactions that transfer mechanical forces from one molecule to the next. In this chapter we use the term entanglement in a very general way, so that it includes topological entanglements (one polymer chain is physically wrapped around another), chemical entanglements (attractive intermolecular interactions between polymer chains), and surface adsorption (attractive intermolecular interactions between polymer chains and a particle surface, e.g., from a filler). The important, fundamental characteristic is that it is an interaction that allows a mechanical stress on one molecule to be distributed or transferred to another molecule with which it is entangled. 

The temperature dependence of the Payne effect has been studied by Payne and other authors [28, 32, 47]. With increasing temperature an Arrhe-nius-like drop of the moduli is found if the deformation amplitude is kept constant. Beside this effect, the impact of filler surface characteristics in the non-linear dynamic properties of filler reinforced rubbers has been discussed in a review of Wang [47], where basic theoretical interpretations and modeling is presented. The Payne effect has also been investigated in composites containing polymeric model fillers, like microgels of different particle size and surface chemistry, which could provide some more insight into the fundamental mechanisms of rubber reinforcement by colloidal fillers [48, 49]. 

The principles of compounding were reviewed earlier in this text and cover the fundamental characteristics of polymers, filler systems, and the basics of vulcanization in the context of compound development for tire applications. A compound formulation consists of four basic components the polymer network, the filler or particulate reinforcing system, the stabilizer system, and the vulcanization system (Figure 14.21). In addition a series of secondary materials such as resins, processing oils, and short fiber reinforcements may be included in a formula (Duddey, 2004 Rodgers and Waddell, 2004 Long, 1985). Elastomers used in radial tires are basically of four types ... 

For filled polymers, it has been observed experimentally [88-90] and numerically [91] that the degree of strain hardening generally decreases with increasing particle concentration. The chemical nature of filler is one of the fundamental characteristics that determine its reactivity. 

A generalized table of fundamental filler characteristics is given in Table 6.1 for a range of carbonate and kaolin grades as well as typical filler titanium, talc and precipitated silica. By developing an understanding of how these fundamental... 

In summary, it is of paramount importance for the papermaker to have a clear idea of the performance attributes which are to be achieved by filler. With that information and a cursory understanding of how the fundamental filler characteristics scale up to application performance, cost-effective paper grade design is possible. 

Yang L, et al (2004) Revised Kubelka-Munk Theory. II. Unified framework for homogeneous and inhomogeneous optical media. Journal Opt. Soc. Am. A 21(10) 1942 McLain L, Wygant R (2005) Fundamental Filler Characteristics for Maximum Sheet Performance, Paper presented at AEL Metsko s Stock Preparation and Uses of Various Pulps Workshop, Munich, Germany, November 2005... 

It is well known that experimental techniques are fundamental for proper characterization of the morphology of polymer/inorganic hybrids. In this scenario, microscopy techniques, such as SEM, TEM, and SPM, play a fundamental role in the characterization of the microstructure of particles, giving deep insight into the dispersion of inorganic fillers into the polymer matrices and helping to establish a more precise relationship between polymerization conditions and morphological characteristics of the particles. 

A morphological characteristic, which is of fundamental importance to the understanding of the structure-property relationship of nanocomposites, is the surface area/volume ratio of the fillers [37]. As illustrated in Fig. 1, the change in particle diameter, layer thickness, or fibrous material diameter from micrometer to nanometer changes the surface area/volume ratio by three orders of magnitude. At this scale, there often is a distinct size dependence of the material properties. In addition, the properties of the composite became dominated by the properties of the interface or interphase when the interfacial area drastically increased. 

Modern compounding, especially for technical or engineering plastics, may require the addition of a complex range of materials, each with its own characteristics. The sequence in which these are introduced into the compounder (and the position down the screw) is fundamentally Important. Fillers, with their weight and volume, are usually brought in first, but the latest technology, in which polymerization or cross-linking takes place in the extruder, may alter the sequence. 

One of the most important characteristics of fillers, connected to their chemical nature, is the fundamental value of free surface energy. Because the... 

Vibration is a major destmctive force in many types of machinery. Vibration can lead to wear and fatigue failure of rigid materials like alloys and plastic components. The helicopter benefits from the unique flexibility and vibration dampening characteristics of elastomeric adhesives. Elastomers are used to transfer torque to the rotor blades while providing flexibility and vibration control. Rubber tires are another example of elastomeric adhesive use. Consumers have enjoyed a steady increase in the useful life expectancy of rubber tires due to improvements in adhesion between the elastomer, tire cords, and the filler. The rubber tire industry has driven a great deal of the fundamental research on elastomeric materials in engineering design. 

Most of the properties of polymers discussed earlier in this chapter are intrinsic ones— that is, they are characteristic of or fundamental to the specific polymer. Some of these properties are related to and controlled by the molecular structure. Often, however, it is necessary to modify the mechanical, chemical, and physical properties to a much greater degree than is possible by the simple alteration of this fundamental molecular structure. Foreign substances called additives are intentionally introduced to enhance or modify many of these properties and thus render a polymer more serviceable. Typical additives include filler materials, plasticizers, stabilizers, colorants, and flame retardants. 

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