Spherical fillers titanium dioxide

Many inert pigments (often known as fillers) are incorporated into paper in addition to the cellulosic fibres. They may be added to improve certain optical properties—in particular opacity and brightness—or simply as a cheap replacement for costly fibre. The two most common pigments are kaolin (china clay) and chalk (limestone), but talc and speciality pigments such as titanium dioxide are also used. The particle size for general purpose fillers is normally expressed as an equivalent spherical diameter (esd) and this is determined from sedimentation data. Values for the common paper-... 

The last few years have seen the extensive use of nanoparticles because of the small size of the filler and the corresponding increase in the surface area, allowing to achieve the required mechanical properties at low filler loadings. Nanometer-scale particles including spherical particles such as silica or titanium dioxide generated in-situ by the sol-gel process (4-8), layered silicates (9-12), carbon (13) or clay fibers(14,15), single-wall or multiwall carbon nanotubes (16,17) have been shown to significantly enhance the physical and mechanical properties of rubber matrices. 

Additives used in final products Fillers antimony trioxide, aramid, barium sulfate, boron nitride, calcinated kaolin, carbon black, carbon fiber, glass fiber, glass spheres, mica, montmorillonite, talc, titanium dioxide, zinc borate Antistatics antimony-doped tin oxide, carbon nanotubes, polyaniline, polyisonaphthalene Antiblocking calcium carbonate, diatomaceous earth, silicone fluid, spherical silicone resin, synthetic silica Release calcium stearate, fluorine compounds, glycerol bistearate, pentaerythritol ester, silane modified silica, zinc stearate Slip spherical silica, silicone oil ... 

It is seen that spherical fillers like glass beads do not affect the normal stress difference. Particulate fillers like titanium dioxide, calcium carbonate and carbon black, reduce the normal stress difference whereas fibrous fillers like aramid, glass and cellulose fibers, increase it. The large increase in normal stresses of fiber filled polymer systems is explained on the basis of the hydrod)mamic particle effect, associated with orientation in the flow direction. Of course, if the fiber diameter is very small then the increase in normal stresses is small and at times may even show a decrease. 

Abstract This chapter describes the influence of three-dimensional nanofillers used in elastomers on the nonlinear viscoelastic properties. In particular, this part focuses and investigates the most important three-dimensional nanoparticles, which are used to produce rubber nanocomposites. The rheological and the dynamic mechanical properties of elastomeric polymers, reinforced with spherical nanoparticles, like POSS, titanium dioxide and nanosdica, were described. These (3D) nanofillers in are used polymeric matrices, to create new, improved rubber nanocomposites, and these affect many of the system s parameters (mechanical, chemical, physical) in comparison with conventional composites. The distribution of the nanosized fillers and interaction between nanofUler-nanofiUer and nanofiller-matrix, in nanocomposite systems, is crucial for understanding their behavior under dynamic-mechanical conditions. 

Chapter 4 investigates the rheological and the dynamic mechanical properties of rubber nanocomposites filled with spherical nanoparticles, like POSS, titanium dioxide, and nanosilica. Here also the crucial parameter of interfacial interaction in nanocomposite systems under dynamic-mechanical conditions is discussed. After discussing about filled mono-matrix medium in the first three chapters, the next chapter gives information about the nonlinear viscoelastic behavior of rubber-rubber blend composites and nanocomposites with fillers of different particle size. Here in Chap. 5 we can observe a wide discussion about the influence of filler geometry, distribution, size, and filler loading on the dynamic viscoelastic behavior. These specific surface area and the surface structural features of the fillers influence the Payne effect as well. The authors explain the addition of spherical or near-spherical filler particles always increase the level of both the linear and the nonlinear viscoelastic properties whereas the addition of high-aspect-ratio, fiberlike fillers increase the elasticity as well as the viscosity. 

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