Clay reinforcement characterization

Huang X, Netravali AN (2006) Characterization of Nano-clay reinforced phytagel modified soy protein concentrate. Biomacromolecules 7 2783-2789 Hill S (1997) Cars that grow on trees. New Scientist Feb 3-39... 

Volume 1 of this book is comprised of 25 chapters, and discusses the different types of natural rubber based blends and IPNs. The first seven chapters discuss the general aspects of natural rubber blends like their miscibility, manufacturing methods, production and morphology development. The next ten chapters describe exclusively the properties of natural rubber blends with different polymers like thermoplastic, acrylic plastic, block or graft copolymers, etc. Chapter 18 deals entirely with clay reinforcement in natural rubber blends. Chapters 19 to 23 explain the major techniques used for characterizing various natural rubber based blends. The final two chapters give a brief explanation of life cycle analysis and the application of natural rubber based blends and IPNs. 

One kind of nanometer-size reinforcements are layered silicates or clays. Among these reinforcements, the use of montmoriUonites and bentonites is interesting because added to their environmental and economic importance (Zampori et al. 2008), their natural abundance and their mechanical and chemical resistance makes them very useful as polymeric material reinforcements. This type of clay is characterized by a moderate negative charge (known as cation exchange capacity, CEC, and expressed in meq/100 gr) (Mandalia and Bergaya 2006 He et al. 2006). 

In summary, the XRD and TGA data revealed that the clay-char formed during pyrolysis of the PS-MMT nanocomposite has a layered structure with an invariable 1.3-nm mass fraction of 28% carbonaceous material, of two types, which differ primarily in their thermooxidative stability. Although this char characterization study revealed little about the mechanistic details of how the clay-char forms, it did result in a more complete picture of the nature of the clay-reinforced carbonaceous char. 

Bionanocomposites have benefited from the advances in nanocomposites that have been studied since the early 1990s when researchers created composites using nanostructured clay reinforcements (i.e., nanoscale clay particles imbedded in polymer matrices) that provided significant improvements in dimensional stability, stiffness, and heat distortion temperature relative to the nascent polymer [14-17]. Since then, many other pioneering works along with further achievements in characterization techniques and synthesis of new nanomaterials have opened up many research avenues, leading to a vast number of biopolymer matrices and nanostructured reinforcements that can be used to produce bionanocomposites. 

Addition of clay also inproved stiflhess as shown in Figure 8. An increase in modulus is observed for conposites of clay lA and clay 2A when eonpared with neat PMR-15. Clay lA produces a greater inerease than clay 2A. The difference in properties can be attributed to the differences in intra-gaUery molecular orientation, as described by Campbell and Scheiman [28]. Several studies have found an increase in TOS also increase in modulus by about 30% has been rqx)rted [6,8-12,28,33-35]. While these improvements are expected from clay reinforcement, other studies have shown that modulus values do not always increase significantly [31,33], and TOS is sometimes not affected by the inclusion of clay [13]. This implies that more work is needed to fully characterize the current system. 

Masenelli-Varlot, K., Vigier, G., and Vermogen, A. 2007. Quantitative structural characterization of polymer-clay-nanocomposites and discussion of an "ideal" microstructure, leading to the highest mechanical reinforcement. 

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. 

Crosslinked NR nanocomposites were prepared with montmorillonite. Morphology was characterized using transmission electron microscopy (TEM), wide-angle X-ray scattering (WAXS), and dynamic mechanical analysis (DMA). X-ray scattering patterns revealed clay intercalation and TEM showed dispersion with partial delamination. The loss modulus peak broadened with clay content, while Tg remain constant. Montmorillonite reinforced the rubber. The DMA exhibited non-linear behaviour typified as a Payne effect (see Section 20.11) that increased with clay content and was more pronounced for this type of nanocomposite. Viscoelastic behaviour was observed under large strains via recovery and stress relaxation. ... 

In Section 23.2 was discussed the theory of reinforcement of polymer and elastomers which refers to the Guth-Gold-Smallwood equation (Equation (23.1)) to correlate the compound initial modulus (E ) with the filler volume fraction ( ). Moreover, it was already commented on the key roles played by the surface area and by the aspect ratio (/). Basic feature of nanofillers, such as clays, CNTs and nanographites, is the nano-dimension of primary particles and thus their high surface area. This allows creating filler networks at low concentrations, much lower than those typical of nanostructured fillers, such as CB and silica, provided that they are evenly distributed and dispersed in the rubber matrix. In this case, low contents of nanofiller particles are required to mutually disturb each other and to get to percolation. Moreover, said nanofillers are characterized by an aspect ratio /that can be remarkably higher than 1. Barrier properties are improved when fillers (such as clays and nanographites) made by... 

Abstract In this chapter, we report the findings of experimental investigations conducted on durability of glass fiber-reinforced polymer (GFRP) composites with and without the addition of montmorillonite nanoclay. First, neat and nanoclay-added epoxy systems were characterized to evaluate the extent of clay platelet exfoliation and dispersion of nanoclay. GFRP composite panels were then fabricated with neat/modified epoxy resin and exposed to six different conditions, i.e. hot-dry/wet, cold-dry/wet, ultraviolet radiation and alternate ultraviolet radiation-condensation. Room temperature condition samples were also used for baseline consideration. 

Dufresne A, Dupeyre D, Paillet M (2003) Lignocellulosic flour-reinforced poly(hydroxybut5 rate-co-valerate) composites. J Appl Polym Sci 87 1302-1315 Durmus A, Kasgoz A, Macosko CW (2007) Linear low density polyethylene (LLDPE)/clay nanocomposites. Part 1 structural characterization and quantifying clay dispersion by melt rheology. Polymer 48 4492 502... 

C5 ras VP, Manfredi LB, Ton-That M-T, Vazquez A (2008) Physical and mechanical properties of thermoplastic starch/montmorillonite nanocomposite films. Carbohydr Polym 73 55-63 de Morals Teixeira E, Correa A, Manzoli A, de Lima Leite F, de Oliveira C, Mattoso L (2010) Cellulose nanofibers from white and naturally colored cotton fibers. Cellulose 17 595-606 de Moura MR, Aouada FA, Avena-Bustillos RJ, McHugh TH, Krochta JM, Mattoso LHC (2009) Improved barrier and mechanical properties of novel hydrox5q)ropyl methylcellulose edible films with chitosan/tripolyphosphate nanoparticles. J Food Eng 92 448—453 Dean K, Yu L, Wu DY (2007) Preparation and characterization of melt-extruded thermoplastic starch/clay nanocomposites. Compos Sci Technol 67 413 21 Duanmu J, Gamstedt EK, Rosling A (2007) Hygromechanical properties of composites of crosslinked allylglycidyl-ether modified starch reinforced by wood fibres. Compos Sci Technol 67 3090-3097... 

Despite the enormous number of scientific papers and patents published recently concerning the preparation and characterization of polymer matrix nanocomposites reinforced and modified with intercalated or exfoliated clays, systems based on SBS as polymeric matrix are relatively poorly investigated. 

Some works on sPS are present, but essentially they regard the incorporation of organophilic clays (Park et al., 2001) and the characterization of sPS/clay nanocomposites with respect to the crystallization behavior (Tseng, Lee, and Chang, 2001 Wu et al., 2004), mechanical properties (Ho Kim et al., 2004), and moldability by means of injection-molding process (Sorrentino, Pantani, and Brucato, 2006). A work on the reinforcing of sPS by means of carbon nanocapsules is also present (Wang et al., 2008). 

Polymer-based nanocomposites have been widely developed over the last two decades due to their highly specific mechanical properties compared to conventional polymer-based microcomposites [1], The reinforcement mechanism in nanocomposites may be attributed to the strong inter-particle and particle-matrix interactions due to the large specific surface area. Among this recent class of materials, the most intensive researches are focused on polymer-based nanocomposites reinforced with inorganic montmorillonite clay, and especially on their synthesis and characterization. However, their micromechanical modeling has been less investigated so far. 

The theory, processes, and characterization of short fiber reinforced thermoplastics have been reviewed by De and White [31], Friedrich et al. [32], Summerscales [33], in an introductory text by Hull and Clyne [34], and in a handbook by Harper [35]. Natural fibers and composites have been reviewed by Wallenberger and Weston [36]. The introduction of new composite materials, called nanocomposites, has resulted in new materials that are being applied to various industrial applications. These materials have in common the use of very fine, submicrometer sized fillers, generally at a very low concentration, which form novel materials with interesting morphology and properties. Nanocomposites have been discussed in a range of texts including two focused on polymer-clay nanocomposites by Pinnavaia and Beall [37] and Utracki [38]. 

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