Nanosized fillers

Other very promising nanosized fillers have been developed, of which carbon nanotubes are amongst the most promising ones due to their high stiffness and strength as well as their outstanding electrical conductivity. 

However, in both cases - thermoplastics and thermosets - the equipment and the processes need to be adapted to the nanosized fillers. The most crucial point in the production of polymer-nanofiller dispersions is the proper separation of the CNTs from each other, the deagglomeration of agglomerates, and their coupling to the polymeric matrix material. For this purpose, dispersion aids, stabilizers, and compatibilizers, used for other filler particles, need to be adapted in many cases specifically for nanosized fillers with their different surface treatments for the different matrix materials. This is a very complicated issue, and makes a close co-operation between the different scientific disciplines necessary [1]. 

Nanocomposites refer to the combination of nanosized fillers (10 m diameter) with polymers, rather than the combination of polymer matrix (filled with nanoparticles) and fiber reinforcement The most popular fillers used as fire retardants are layered silicates. Loading of 10% or less (by weight) of such fillers significantly reduces peak heat release rates and facilitates greater char production [7]. The char layer provides a shielding effect for the composites below and the creation of char also reduces the toxicity of the combustion products, as less carbon is available to form the CO and CO2. 

We have also shown that electrospun fibres can be functionalised by the use of additives, and fillers of many kinds can be used to form composite fibres. The properties of electrospun fibres can be modified using nanosized fillers. Carbon nanotubes (CNT) are widely used as fillers in electrospun fibres. Typically, their function is to serve as a reinforcement component in electrospun polymeric fibres. 

Keywords Nanocomposites, polymer nanocomposites, plasmonics, ZnO-based nanocomposite films, nanosized fillers, nanocomposite solar cells, nonvolatile memory devices, magnetic fiuorescent nanocomposites... 

Fillers such as CaCOs, clay, etc. with average particle size in the range 01 to 100 nm may be defined as nanofillers. Unlike traditional fillers, mainly used for cost reduction, nanofillers are performance-enhancing fillers used in relatively small amounts (5 10%) in order to provide substantial improvements in physical and other properties. Nanosized particles (average diameter around 40 nm) form a very fine and homogeneous distributed system in polymer matrix. As compared to micron size filler particles the nanosized filler particles are able to occupy substantially greater number of sites in the polymer matrix. 

The significant increase in specific surface area of filler particles contributes to the enhanced physical property of the polymer matrix. Nanosized fillers increase barrier properties by creating a maze or tortuous path that slows the progress of gas molecules through the polymer matrix, thereby substantially improving the gas/air permeability of the polymer. Nanosized fillers in a polymer matrix substantially improve surface properties like gloss, surface finish, grip (friction), etc. 

Effects of Nanosized Fillers on Mechanical Properties of Natural Rubber Composites... 

All chapters have been updated and, some, significantly expanded vs. the first edition. Two chapters, however, due to unavailabilty of the authors remain essentially the versions that appeared in the 2005 edition of this book, with only minor modifications in the References section. Information on the rapidly grovring field of nanosized fillers can now be found, not only in Chapters 9 and 10, but also in many other chapters of the book (see, for example. Chapters 1, 2, 3, 5,12,17,18, 20, 22, 24). 

Fillers are typically used to enhance specific properties of polymers, and the polymer/ nanocomposites based on nanoclays have gained attention because of their ability to improve the mechanical, thermal, barrier, and fire-retardant properties of polymers [3]. Nanosized fillers have been introduced in a wide spectrum of applications ranging from providing photocatalyst activation and conductivity to improve melting... 

A more recent approach followed to improve the conductivity of clay films consists of the introduction of metal nanoparticles (NPs) [33] or graphene [34]. Obviously, the efforts to develop these composite materials originate with the well-known electrocatalytic properties of the nanosized filler, inducing the search for supports able to meet with many different experimental requirements. 

As previously mentioned, in the uncured state, thermosetting materials are generally mixtures of small reactive molecules that form networks catalysts, initiators and/or accelerators and particulate, fiber-based, or nanosize fillers. There... 

Recent studies also reveal that nanosized fillers are more effective in enhancing the ionic conductivity, lithium ion transference number and electrochemical stability (Kumar et al., 1994). Wang et al. (2010) introduced a fast ionic conductor with Lij jAlSO jTij 7(PO )j as filler in the PEO matrix. The authors achieved a high ionic conductivity of 4.53 x 10 S/cm at room temperature. 

In the present conmiunication effect of nanosized filler particles of AI2O3 on electrical and dielectric properties of PVA based SPE have been investi ted. 

The properties of PLA such as thermal stability and impact resistance are inferior to those of conventional polymers used for thermoplastic applications. Therefore, PLA is not ideally suited to compete against the conventional polymers [5]. In order to improve the properties of PLA and increase its potential applications, copolymers of lactic acid and other monomers such as derivatives of styrene, acrylate, and poly (ethylene oxide) (PEO) have been developed. PLA has also been formulated and associated with nanosized fillers. Modification of PLA, copolymerization with other monomers, and PLA composites are some approaches that have been used to improve the properties of PLA, such as stiffness, permeabiUty, crystallinity, and thermal stability [1-5]. Considerable research is being done to develop and study modified PLA, PLA-based copolymers, and PLA-based composites. 

Electrically conductive polymer nanocomposites are widely used especially due to their superior properties and competitive prices. It is expected that as the level of control of the overall morphology and associated properties increases we will see an even wider commercialisation on traditional and totally novel applications. In this section we have discussed the basic principles of the percolation theory and the different types of conduction mechanisms, outlined some of the critical parameters of controlling primarily the electrical performance and we have provided some indications on the effect such conductive fillers have on the overall morphology and crystallisation of the nanocomposite. The latter becomes even more critical if we take into consideration that modem nanosized fillers offer unique potential for superior properties at low loadings (low percolation thresholds) but have a more direct impact on the morphology of the system. Furthermore we have indicated that similar systems can have totally different behaviour as the preparation methods, the chain conformation and the surface chemistry of the fillers will have a massive... 

Composite materials are heterogeneous systems composed of at least by two different phases, commonly designated as matrix and reinforcement. These designations are associated with the distinct properties (mechanical, thermal or electric) of the two phases. The reinforcement can be of micro- (microcomposites) or nanosize (nanocomposites). The field of nanocomposites is a rapidly expanding area of research generating new materials with unique properties. Several new materials have been developed within the last decade incorporating nanosized filler materials in polymer matrices. 

Organic/inorganic nanocomposites prepared by in situ polymerization methods have received extensive attention in recent years. Unlike microscale fillers, nanoscale fillers can offer excellent properties to a polymer matrix. Nanosized filler, with a few weight percent in the reinforced polymer nanocomposites, strongly influences the macroscopic properties of the polymer. The resultant polymer nanocomposites can significantly improve some of their properties, such as higher heat distortion temperatures, enhanced flame resistance, increased modulus, better barrier properties, reduced thermal expansion coefficient, and altered electronic and optical properties. 

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. 

Introduction of fillers can affect the morphology and change the viscoelastic behaviour of the polymers by introducing filler-matrix interactive forces or restriction of polymer chain mobility by the presence of filler particles. It is thus of much interest to study the viscoelastic behaviour of polymers filled with nanosized fillers, where the nanoparticle size allows interactions with polymer at the molecular level. 

The addition of nanosized fillers can result in the improvement of thermomechanical, transparency, and film barrier properties. However, it was shown that nanoclay reduces the efficiency of the light stabilizers, which was ascribed to adsorption of the stabilizers onto the hydrophilic nanoplatelets [216]. If the nanoparticles contain Fe impurities, these can accelerate the photodegradation however, this negative effect can be reduced by applying metal deactivators [217]. 

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