Nanofillers hybrid fillers

NR composites and nanocomposites can be fabricated by three main techniques, namely latex compounding, solution mixing and melt blending. A variety of nanofillers, such as carbon black, silica, carbon nanotubes, graphene, calcium carbonate, organomodified clay, reclaimed rubber powder, recycled poly(ethylene terephthalate) powder, cellulose whiskers, starch nanocrystals, etc. have been used to reinforce NR composites and nanocomposites over the past two decades. In this chapter, we discuss the preparation and properties of NR composites and nanocomposites from the viewpoint of nanofillers. We divide nanofillers into four different types conventional fillers, natural fillers, metal or compound fillers and hybrid fillers, and the following discussion is based on this classification. 

A large-scale application of rubber nanocomposites, such as the one in the tyre industry, reasonably implies the use of hybrid filler systems, with a minor amount of nanofiller added to a major part of a traditional filler, such as silica or carbon black. 

Recentiy, a new class of organic-inorganic hybrid materials based on the ultra incorporation of nano-sized fillers (nanofillers) into a polymer matrix has been investigated. Nanotechnology is the aptitude to work on a scale of about 1-100 nm in order to understand, create, characterize and use material structure, devices, and system with unique properties derived from their base on the nanostructures. Nanocomposites could exhibit exclusive modifications in their properties, compared with conventional composites in terms of physical properties, including gas barrier, flammability resistance, thermal and environmental stability, solvent uptake, and rate of biodegradability of biodegradable (Chivrac et al. 2009). 

This chapter focuses on the non-linear viscoelastic behavior of rubber composites and nanocomposites. Here, we have discussed about the effect of individual fillers (mineral fillers, nanotubes, carbon nanofillers, fibrous nanofiUers, biofillers, special structured fillers viz. nanorods, nanowires, nanoflowers etc.) on the linear/ nonlinear viscoelastic behavior of rubber composites. Moreover, as this chapter is more concerned on the non-linear viscoelastic behavior, we have also discussed the effect of hybrid fillers on the nonUnear viscoelastic behavior of rubber composites in more detail. 

The interaction and subsequent oxidative behavior under UV light exposure of nanocomposite using poly(styrene) (PS) as polymer and LDH organomodified by a monomer surfactant as filler were recently investigated [115]. The photooxidation study revealed that the hybrid nanofiller did not modify the photooxidation mechanism of PS. The same products of oxidation were observed with the same proportions. A slightly higher oxidation rate was observed in the case of the sample with 5% of filler. The advantage of this system was its ability to be tailored in order to limit/ control eventual interactions with photostabilizers and antioxidants. 

Although many kinds of fillers and fibers have been added to POs over the years, and new ones continue to be developed, the sections below cover the most used and most commercially important materials. These fillers and fibers continue to draw the greatest efforts from industry and academia for further development and improvement. Some newer kinds, such as nanofillers and plant-based fibers, are included here mainly because of their potential future importance. As in other chapters of this book, here the focus is more on materials that can be added in a typical compounding operation or "at the press"—rather than modifiers that are added more upstream by the resin producer, or hybrid combinations of materials, such as glass-mat composites or laminates, where the reinforcing material is not added during screw processing. 

Spherical Particles Nanofiller with three dimensions in the nanometer regime are the spherical nanofillers obtained by sol-gel process [9, 10]. In sol-gel process the organic/inorganic hybrid material can be formed by the condensation reaction between the functionalized prepolymer and the metal alkoxides, leading to the formation of a chemical bond between the polymer and the inorganic filler. Therefore, the incorporation of filler particles in polymer through the sol-gel process avoids the aggregation of filler. 

Addition of small amount of nanofillers may improve the properties of mbber and thermoplastics. In the polymer industry, polymer-filler nanocomposites are a promising class of material that offers the possibility of developing new hybrid materials with desired set of properties. Properties of mbbers and thermoplastics which have shown substantial improvements due to the incorporation of nanoparticles, are mechanical properties, decreased permeability to gases, water and hydrocarbons, thermal stability and heat distortion temperature, flame retardancy and reduced smoke emissions, chemical resistance, surface appearance, electrical and thermal conductivity, optical clarity in comparison to conventionally filled polymers [107]. 

A polymer blend/nanocomposite can be defined as a polymer-nanofiller systan in which the inorganic filler is on a nanometric scale at least in one dimension and it can be a polymer/nanoparticle blend or a hybrid. The composite interconnection can be based on a secondary force or physical entanglement [6]. In turn, the polymer/nanofiller hybrid is formed when the polymer and the nanoparticle are covalently bonded. The covalent bond can be formed during the in situ polymerization (the monomer or the growing polymer chain can react with the filler particle) or during the composite processing. 

As for the thermodynamic consideration in Section 2.2.1, we attempt to highlight these challenges by describing in some detail the most common synthetic routes for nanocomposite formation employed for polymer/layered-inorganic hybrids. Most examples are drawn from layered-silicate fillers, but the conclusions are general across most nanofillers, and one should be able to envision similar strategies for nanocomposite formation based on other types of nanofillers. 

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