Composites metal oxide-based nanocomposites

Metal oxide-metal oxide-based nanocomposites, Me 0-Me 0, are also interesting for gas sensor design (Yamazoe et al. 1983 Yamazoe 1991 Ferroni et al. 1999 Yamaura et al. 2000 Comini et al. 2002 Korotcenkov 2007 Gas kov and Rumyantseva 2009). It was established that one of the ways for improving selectivity and stability of metal oxide conductometric gas sensors is the modification of metal oxide, Me O by the introduction of catalytic or structure modifiers, Me 0, in the nanostruc-tured metal oxide matrix and, thereby, the development of nonhomogeneous complex materials, i.e., nanocomposites Me 0-Me 0. It was also expected that other highly sophisticated surface-related properties important for gas sensor applications such as optical, electronic, catalytic, mechanical, and chemical can also be obtained in complex metal oxides and composites. 

Table 14.3 presents effects which can be achieved in metal oxide-based composites. It is seen that the use of nanocomposites in gas sensors really can produce great improvements in sensor parameters. 

It is the aim of this chapter to give an overview on both chemical and electrochemical techniques for producing metallic-particle-based CP nanocomposite materials and to outline the progress made in this field. The various synthetic approaches are organized in such a way as to present first those involving metal particle deposition in the course of polymerization, and subsequently post-polymerisation procedures that involve chemical, electrochemical, or adsorption processes (Figure 7.1). Well-established approaches, along with some newly developed techniques will be discussed, with special emphasis on those that are still underdeveloped. Synthesis of metal oxide particle-based CP composites (see e.g. [8]), as well as modification of CPs with transition-metal complexes (see e.g. [5]) remain outside the scope of this chapter. 

Almost all types of vegetable oil-based polymer nanocomposites, that is clay/polymer nanocomposites, carbon nanotubes/polymer nanocomposites, metal nanoparticles/polymer nanocomposites (metals such as Ag, Cu, Fe and their oxides) are found in the literature. These have several advantages over their respective pure polymers, or conventional polymer composite systems, and thus have the potential to meet the current demand for advanced polymeric materials. 

In the last decade, considerable progress was observed in the field of PO/compatibil-izer (predominantly on the base of PO-g-MA)/organo-surface-modified clay nanocomposites. Polyethylene (PE), polypropylene (PP), and ethylene-propylene (EP) rubber are one of the most widely used POs as matrix polymers in the preparation of nanocomposites [3,4,6,30-52]. The PO silicate/silica (other clay minerals, metal oxides, carbon nanotubes, or other nanoparticles) nanocomposite and nanohybrid materials, prepared using intercalation/exfoliation of functionalized polymers in situ processing and reactive extrusion systems, have attracted the interest of many academic and industrial researchers because they frequently exhibit unexpected hybrid properties synergisti-cally derived from the two components [9,12,38-43]. One of most promising composite systems are nanocomposites based on organic polymers (thermoplastics and thermosets). 

This is Volume 2 of Natural Rubber Materials and it covers natural rubber-based composites and nanocomposites in 27 chapters. It focuses on the different types of fillers, the filler matrix reinforcement mechanisms, manufacturing techniques, and applications of natural rubber-based composites and nanocomposites. The first 4 chapters deal with the present state of art and manufacturing methods of natural rubber materials. Two of these chapters explain the theory of reinforcement and the various reinforcing nanofillers in natural rubber. Chapters 5 to 19 detail the natural rubber composites and nanocomposites with various fillers sueh as siliea, glass fibre, metal oxides, carbon black, clay, POSS and natural fibres ete. Chapters 20-26 discuss the major characterisation techniques and the final ehapter covers the applications of natural rubber composites and nanoeomposites. By covering recent developments as well as the future uses of rubber, this volume will be a standard reference for scientists and researchers in the field of polymer chemistry for many years to come. 

Metal oxide nanopowders/nanoparticles were used in such composites for the same purpose. It was proven that the addition of potassium titanate (Liang et al. 2005), aluminum borate (Gu and Liang 2007), or zirconia (Yan et al. 2007) nanoparticles improved the wear resistance and decreased the friction coefficient of nanocomposites. When the nanoparticles were previously modified (in zirconia-based composites, with A-[2-aminoethyl]-Y-aminopropylmethyldimethoxysilane, and Si- and P-based compounds in potassium titanate containing composites), the tribological behavior of the composites was superior due to the improved dispersion of the filler. 

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