Polymer/clay nanocomposites biodegradable properties

Nanocomposites materials can be defined as composite materials, that combine one or more separate components in order to improve performance properties, for which at least one dimension of the dispersed particles is in the nanometer range [23]. In polymer clay nanocomposites, nanoscale particles have typically 10-100 nm in size [24]. Depending on the reinforcement, remarkable improvement in material properties when compared with neat polymer or conventional micro and macro-composites can be obtained. These improvements can include high moduli, increased strength and heat resistance, decreased gas permeability and flammability, and increased biodegradability of biodegradable polymers [25]. 

This chapter aims to review the developments of biobased polymer/clay nanocomposites comprising general fabrication techniques and optimization of mixture homogeneity in solutions. Furfliermore, the effects of interactions between biopolymer matrices and nanoclays on structural, mechanical, and thermal properties, and biode-gradabUity of currently available biobased polymer nanocomposites are reviewed. Finally, future trends are also summarized for such nanocomposites with great enhancements of mechanical, thermal, and biodegradable properties. 

The principal used in polymer-clay nanocomposites leads the individual clay layers as well as the polymer chains to function more effectively with numerous improved properties such as high moduli, increased strength and heat resistance, decreased gas permeability and flammability, increased biodegradability of biodegradable polymers, and attractive electrical properties when compared to virgin polymers or conventional micro- and macrocomposites [37]. These properties make them ideal materials for applications in food packaging, structural automotive components, and electronics among others. 

This book covers both fundamental and applied research associated with polymer-based nanocomposites, and presents possible directions for further development of high performanee nanocomposites. It has two main parts. Part I has 12 chapters which are entirely dedicated to those polymer nanocomposites containing layered silicates (clay) as an additive. Many thermoplastics, thermosets, and elastomers are included, such as polyamide (Chapter 1), polypropylene (Chapter 4), polystyrene (Chapter 5), poly(butylene terephthalate) (Chapter 9), poly(ethyl acrylate) (Chapter 6), epoxy resin (Chapter 2), biodegradable polymers (Chapter 3), water soluble polymers (Chapter 8), acrylate photopolymers (Chapter 7) and rubbers (Chapter 12). In addition to synthesis and structural characterisation of polymer/clay nanocomposites, their unique physical properties like flame retardancy (Chapter 10) and gas/liquid barrier (Chapter 11) properties are also discussed. Furthermore, the crystallisation behaviour of polymer/clay nanocomposites and the significance of chemical compatibility between a polymer and clay in affecting clay dispersion are also considered. 

Le Digabel F, Boquillon N, Dole P et al (2004) Properties of thermoplastic composites based on wheat-straw lignocellulosic fillers. J Appl Polym Sci 93 428-436 Lee S -R, Park FI-M, Lim H et al (2002) Microstructuie, tensile properties, and biodegradability of aliphatic polyester/clay nanocomposites. Polymer 43 2495-2500 Lee SFI, Ohkita T, Kitagawa K (20(M) Eco-composite from poly(lactic acid) and bamboo fiber. Flolzforschung 58 529-536... 

Zeppa C, Gouanve Espuche E (2009) Effect of a plasticizer on the structure of biodegradable starch/clay nanocomposites thermal, water-sorption, and oxygen-barrier properties. J App Polym Sci 112 2044-2056... 

Chung Y., Ansari, S., Estevez, L., Hayrapetyan, S., Giannelis, E. R, and Lai, H. M. 2010. Preparation and properties of biodegradable starch-clay nanocomposites. Carbohydrate Polymers 79 391-396. 

The research around the use of montmorillonite to obtaining nanocomposites polymer-MMT has become even more intense. In a review, Biswas and Ray [45] described several features of polymer-MMT nanocomposite materials. Ray and Okamoto [24] reported various characteristics of polymer-layered silicate nanocomposite materials, some of these materials exhibited distinctive properties like biodegradability. Ahmadi et al. [46] reviewed synthetic routes, properties, and future applications of polymer-layered nanocomposites. Significantly, nanocomposites of PAni and PPY with MMT clay via emulsion polymerization technique [47, 48] were found to act as electrorehological fluids, sometimes denominated smart fluids. In this context, Ballav and Biswas [49, 50] reported high yield oxidative polymerization of thiophene, aniline, pyrrole, and furan by MMT— without extraneous oxidant—vis-a-vis nanocomposites formation of the corresponding polymers with MMT. 

When thinking about the environmental effects of plastics, for the products having short life cycle periods - if the mechanical aspects can be fulfilled - it may be convenient to use biodegradable materials. Considering the promising properties and applications of biodegradable polymers as long as their environmental friendly aspects, we decided to start with PLA-clay nanocomposites. 

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