Nanocomposites - An Overview (original) (raw)

Nanocomposites in Food Packaging – A Review

Advances in Diverse Industrial Applications of Nanocomposites, 2011

Brazil 3 USA 2.1 Nanoclays (layered silicates) Nanoclays have been the most studied nanofillers, due to their high availability, low cost, good performance and good processability. The first publications about applications of polymer-nanoclays composites to food packaging date from the 1990's (Ray et al., 2006). The clays for nanocomposites usually are bidimensional platelets with very tiny thicknesses (frequently around 1 nm) and several micrometers in length. In contrast with the typical tactoid structure of microcomposites (conventional composites), in which the polymer and the clay tactoids remain immiscible (Ludueña et al., 2007; Alexandre et al., 2009), the interaction between layered silicates and polymers may produce two types of nanoscale composites (Figure 1), namely: intercalated nanocomposites, which result from penetration of polymer chains into the interlayer region of the clay, producing an ordered multilayer structure with alternating polymer/inorganic layers (Weiss et al., 2006), and exfoliated nanocomposites, which involve extensive polymer penetration, with the clay layers delaminated and randomly dispersed in the polymer matrix (Ludueña et al., 2007). Exfoliated nanocomposites have been reported to exhibit the best properties due to the optimal clay-polymer interactions (Adame & Beall, 2009; Alexandre et al., 2009). The most studied clay is montmorillonite (MMT), whose chemical general formula is M x (Al 4-x Mg x) Si 8 O 20 (OH) 4. MMT is a representative of 2:1 layered phyllosilicates, whose platelets have two layers of tetrahedral silica sheets filled with a central octahedral alumina sheet (Weiss et al., 2006). This kind of clay has a moderate negative surface charge that is important to define the interlayer spacing (Alexandre & Dubois, 2000). The imbalance of the surface negative charges is compensated by exchangeable cations (typically Na + and Ca 2+). The parallel layers are linked together by weak electrostatic forces (Tan et al., 2008). MMT is an excellent reinforcing filler, thanks to its high surface area and large aspect ratio, which ranges from 50 to 1000 (Uyama et al., 2003). The hydrophilicity of the surface of most clays make their dispersion in organic matrices difficult (Kim et al., 2003). Organoclays, produced by interactions of clays and organic compounds, have found an important application in polymer nanocomposites. An adequate organophilization is essencial for successful exfoliation of clays in most polymeric matrices, since organophilization reduces the energy of clays and improves their compatibility with

Polymer Nanocomposites: An Emerging Material Class

ipac.kacst.edu.sa, 2006

Polymer/clay nanocomposites are materials composed of a polymer matrix and nanometer size clay particles. They exhibit significant improvements in tensile modulus and strength, reduced permeability to gases and liquids compared to the pure polymer. These property improvements can be realized while retaining clarity of the polymer without a significant increase in density. Polymeric nanocomposites hold the potential to replace the conventional plastics and plastic composite materials for many applications such as automotive components, packaging, appliances, electrical/electronic parts, and building and construction products. The aim of this study is to review the background and growth of the nanocomposite technology, present some of the data on the property enhancement and evaluate the future of this futuristic material.

Polymer/Clay Nanocomposites: An Emerging Material Class

Polymer/clay nanocomposites are materials composed of a polymer matrix and nanometer size clay particles. They exhibit significant improvements in tensile modulus and strength, reduced permeability to gases and liquids compared to the pure polymer. These property improvements can be realized while retaining clarity of the polymer without a significant increase in density. Polymeric nanocomposites hold the potential to replace conventional plastics and plastic composite materials in many applications such as automotive components, packaging, appliances, electrical/electronic parts, and building and construction products. This paper reviews the background and growth of nanocomposite technology, presents some of the data on property enhancement, and evaluates the future of this emerging class of polymer material.

Morphology, microhardness, and flammability of compatibilized polyethylene/clay nanocomposites

Polymer Engineering & Science, 2010

Morphology, thermal properties, and microhardness of ethylene-glycidyl methacrylate copolymer (EGMA)/clay and ethylene-acrylic ester-glycidyl methacrylate terpolymer (EAGMA)/clay nanocomposites with different clay concentrations have been studied. The results have shown that EGMA and EAGMA are highly compatible with the organoclays Cloisite 1 20A (Cl20A) and Cloisite 1 30B (Cl30B). Intercalated structures are formed in the whole range of Cl20A loadings investigated, whereas partial degradation of the Cl30B organoclay was observed. The thermal characteristics and microhardness of EGMA/clay nanocomposites suggest that the filler dispersion deteriorates at high concentration. The concentrated EGMA/Cl20A nanocomposites have been used as masterbatches to prepare ternary high density polyethylene (HDPE)/Cl20A and low density polyethylene (LDPE)/Cl20A nanocomposites. Diffractometric characterization and scanning electron microscopy observations of these materials have shown that the intercalated structure of the starting EGMA/Cl20A masterbatches is preserved after dilution with the polyolefins. The results suggest that the silicate platelets remain localized within the EGMA droplets in the diluted nanocomposites. The latter display improved microhardness, whereas the mechanical properties, including elongation at break, are comparable with those of the neat polyolefins. Considerable enhancement of the flame retardant properties has been observed for the ternary nanocomposites. POLYM.

The Potential Use of Polymer-Clay Nanocomposites in Food Packaging

International Journal of Food Engineering, 2006

With today's advancement in nanotechnology, Polymer-Clay Nanocomposite has emerged as a novel food packaging material due to its several benefits such as enhanced mechanical, thermal and barrier properties. This article discusses the potential use of these polymer composites as novel food packaging materials with emphasis on preparation, characterization, properties, recent developments and future prospects.