Particulate fillers composition

In general adding reinforcing fibers significantly increases mechanical properties. Particulate fillers of various types usually increase the modulus, plasticizers generally decrease the modulus but enhance flexibility, and so on. These RPs can also be called composites. However the name composites Utterly identifies thousands of different combinations with very few that include the use of plastics (Table 6-18). In using the term com-... 

Modulus Rigid minerals Ductility Ductility produces a more rigid composite. Particulate fillers severely degrade impact strength. 

Particulate composites, 26 754-755 ceramics processing, 5 653-654 extensional modulus of, 26 777 fabrication of, 26 766 Particulate emission limits, 13 183 Particulate emissions, reducing, 11 689 Particulate fillers, ll 302t, 303 for rubber, 21 772, 773 Particulate fluidized-bed regime, 11 801 Particulate impurities in gases, 13 464 in high purity gases, 13 466 Particulate matter (PM), 1 798-801 ... 

Finally, metal- and resin-bonded composites are also classified as particulate composites. Metal-bonded composites included structural parts, electrical contact materials, metal-cutting tools, and magnet materials and are formed by incorporating metallic or ceramic particulates such as WC, TiC, W, or Mo in metal matrixes through traditional powder metallurgical or casting techniques. Resin-bonded composites are composed of particulate fillers such as silica flour, wood flour, mica, or glass spheres in phenol-formaldehyde (Bakelite), epoxy, polyester, or thermoplastic matrixes. 

Hancock M, Rothon RN (1995) Principle types of particulate fillers. In Rothon RN (ed) Particulate-fiUed polymer composites. Longman, Harlow, p50... 

Fig.1. Effect of matrix properties on the tensile yield stress of particulate filled composites. Symbols (O) PVC, (A) LDPE filler CaC03,r=1.8 pm... 

Recently, stress analysis has been carried out for the determination of stress distribution around inclusions in particulate filled composites. A model based on the energy analysis has led to the determination of debonding stress [8]. This stress, which is necessary for the separation of the matrix and filler, was shown to depend on the reversible work of adhesion (see Eq. 16) and it is closely related to parameter B. 

Rothon, R., Effects of particulate fillers on flame retardant properties of composites, in Particulate-Filled Polymer Composites, 2nd edn., Rothon, R.N. (Ed.), Rapra Technology Ltd., Shawbury, U.K., 2003, Chapter 6, p. 271. 

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. 

Equations rdating modulus to composition in isotropic composites are discussed in recent reviews by Manson and Sperling S and by Crowson and Arridge S ore than a dozen equations have been proposed. Tests on polymer composites ow that none of the available equations satisfactorily predicts tiie moduli of all types of composite at all concentrations of rigid particulate filler the best that can be dcme with any certainty is to define upper and lower bounds on the moduli. 

Figure 8.25. The effect of particulate fillers on the compressive strength of epoxy resin. [Adapted, by permission, from Yang Q, Pritchard G, Polym. Polym. Composites, 2, No.4, 1994, 233-9.]...

It was mentioned above that the simulation method of Termonia [67-72] can be used to calculate the stress-strain curves of many fiber-reinforced or particulate-filled composites up to fracture, including the effects of fiber-matrix adhesion. Such systems are morphologically far more complex than adhesive joints. Many matrix-filler interfaces are dispersed throughout a composite specimen, while an adhesive joint has only the two interfaces (between each of the bottom and top metal plates and the glue layer). If one considers also the fact that there will often he a distribution of filler-matrix interface strengths in a composite, it can be seen that the failure mechanism can become quite complex. It may even involve a complex superposition of adhesive failure at some filler-matrix interfaces and cohesive failure in the bulk of the matrix. 

Hancock, M., and Rothon, R. N. (1995). Principle Types of Particulate Fillers, Particulate-Filled Polymer Composites. Rothon, R. N., Ed., Longman Harlow, p. 77. 

Developed carbon composite material with graphite particulate filler to control pore size and speed surface sealing. 

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