Polymer Nanocomposites nanoclay

Keywords Eco-friendly Polymer Nanocomposite Nanoclay Montomorillionite... 

This is another important and widely used polymer. Nanocomposites have been prepared based on this rubber mostly for flame-retardancy behavior. Blends with acrylic functional polymer and maleic anhydride-grafted ethylene vinyl acetate (EVA) have also been used both with nanoclays and carbon nanotubes to prepare nanocomposites [65-69]. 

Recently, new approaches on flame retardancy deal often with nanofillers and in this section some examples of improvements of fire behavior of polymeric foams obtained by use of nanoclays or nanofibers will be shown. Much more details on flame retardancy of polymeric nanocomposite may be found elsewhere as for example in the book edited by A. B. Morgan and C. A. Wilkie105 or in scientific review.106 Polymer nanocomposites have enhanced char formation and showed significant decrease of PHRR and peak of mass loss rate (PMLR). In most cases the carbonaceous char yield was limited to few weight %, due to the low level of clays addition, and consequently the total HRR was not affected significantly. Hence, for polymer nanocomposites alone, where no additional flame-retardant is used, once the nanocomposite ignites, it burns slowly but does not self-extinguish... 

It is generally accepted that thermal stability of polymer nanocomposites is higher than that of pristine polymers, and that this gain is explained by the presence of anisotropic clay layers hindering diffusion of volatile products through the nanocomposite material. It is important to note that the exfoliated nanocomposites, prepared and investigated in this work, had much lower gas permeability in comparison with that of pristine unfilled PE [12], Thus, the study of purely thermal degradation process of PE nanocomposite seemed to be of interest in terms of estimation of the nanoclay barrier effects on thermal stability of polyolefin/clay nanocomposites. 

Goliath Business Knowledge on Demand, Polymer Nanocomposites Report 2006 BCC Research, Polymer Nanocomposites Nanoparticles, Nanoclays and Nanotubes. Report NAN021B, 2004. 

The use of nanoclays in conventional polymer nanocomposites is well known and diffuse. The advantages of the addition of nanoclays to a polymeric matrix are the improvement of mechanical properties, the enhancement of barrier effect, and the increase of chemical and thermal stability. 

Three different types of nanomaterials, based on their dimensional characteristics, are generally used to prepare polymer nanocomposites. These include nanomaterials with only one dimension in the nanometre range (e.g. nano-clay), those with two dimensions in the nanometre scale (e.g. carbon nanotubes) and those that have all three dimensions in the nanometre scale (e.g. spherical silver nanoparticles), as stated earlier. Thus nanosize thin layered aluminosilicates or nanoclays, layer double hydroxide (LDH), a large number of nanoparticles of metals and their oxides, carbon nanotubes and cellulose nanofibres are used as nanomaterials in the preparation of vegetable oil-based polymer nanocomposites. 

Why is it necessary to modify inorganic nanoclays for use in vegetable oil-based polymer nanocomposites ... 

As a result of the existing manufacturing techniques, a great amount of nanomaterials such as nanofibers, carbon nanotubes, SiO and nanoclay is currently available and the use of fiber-reinforced polymer nanocomposites in practical applications is continuously growing. It has been reported in the literature that nanoclays account for approximately 70% of the total volume of commercially used nanomaterials [8]. 

This chapter reviews the use of the sepiolite/palygorskite group of clays as a nanofiller for polymer nanocomposites. Sepiolite and palygorskite are characterized by a needle-like or fiber-like shape. This peculiar shape offers unique advantages in terms of mechanical reinforcement while, at the same time, it allows to study the effect of the nanofiller s shape on the final composite properties. The importance of the nanofiller shape for the composite properties is analyzed in Section 12.2, introducing the rationale of the whole chapter. After a general description of needle-like nanoclays in Section 12.3, the chapter develops into a main part (Section 12.4), reviewing the preparation methods and physical properties of polyolefin/needle-like clay nanocomposites. 

Wood polymer nanocomposites were prepared through impregnation of wood with PF/Nanoclay by another research Islam et al. and their co-researcher [37]. They reported that wood polymer nanocomposites (WPNCs) which were manufactured from five tropical wood species by vacuum-impregnation method have increased dynamic mechanical thermal properties. 

M.S. Islam, S. Hamdan, Z.A. Tahb, A. Ahmed, M.R. Rahman, Tropical wood polymer nanocomposite (WPNC) The impact of nanoclay on dynamic mechanical thermal properties. Compos. Sci. Technol. 72 (2012), 1995-2001 (2012). 

Polymer nanocomposites are one of the highly discussed research topics in recent time. Yehia et al. reported the preparation and the properties of different nanoclays based on sodium montmoriUonite (bentonite) and some organic amines of varying chain lengths (dodecylamine, hexadecylamine and octadecylamine) beside amine-terminated butadiene-acrylonitrile copolymer (ATBN) The nanocomposite clays were incorporated in natural and synthetic rubbers (NR, SBR and... 

Some of the most widely studied and technologically relevant polymer nanocomposites used in PLA technologies are those making use of nanoclays as reinforcing fillers. In order to achieve a full understanding of the nanocomposite behaviour and, therefore, of the system behaviour and performance, it is necessary to understand the structure and characteristics of nanoclays. With this objective, a small section of this chapter is devoted to analyzing the basic concepts of the nanoclays, with special interest in the most interesting/widely used clays for these applications. 

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... 

H. Datta, N.K. Singha, A.K. Bhowmick, Beneficial effect of nanoclay in atom transfer radical polymerization of ethyl acrylate a one pot preparation of tailor-made polymer nanocomposite. Macromolecules 41 (1) (2008) 50-57. 

M. Hemmati, H. Shariatpanahi, A. Fereidoon, J. Aalaie, M.G. Ahangari, Study of a polymer blend/nanoclay nanocomposite of polyethylene and polyamide 6 prepared by mechanical blending, Polymer - Plastics Technology and Engineering 51 (1) (2012) 80-85. 

Marras SI, Kladi KP, Tsivintzelis I, Zuburtikudis I, Panayiotou C (2008) Biodegradable polymer nanocomposites the role of nanoclays on the thermomechanical characteristics and the electrospun fibrous structure. Acta Biomaterialia 4 756-765... 

Nanofillers may be nanoclays, carbon nanotubes (single or multiwall) (CNTs), silica, layered double hydroxides (LDHs), metal oxides, etc., offering the promise of a variety of new composites, adhesives, coatings, and sealant materials with specific properties [32-37]. Among the fillers mentioned, nanoclays have attracted most of the academia and industry interest, due to their abrmdance as raw materials and to the fact that their dispersion in polymer matrices has been studied for decades [38]. In fact, there are three major polymer nanocomposites categories in terms of nanofiller type that are expected to compile the global nanocomposites market in 2011 nanoclay-reinforced (24%), metal oxide-reinforced (19%), and CNTs-reinforced (15%) ones [39-41]. 

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