Nanocomposites barrier materials

Nanocomposite Barrier Materials with Novel Functionalities... 

Ube developed the PA nanocomposite named Ecobesta to replace PVDF or other traditional barrier materials. The all-polyamide structure offers recycling advantages compared to traditional multi-materi designs. It incorporates ... 

Clay-polymer nanocomposites have proven to be interesting candidates as gas barrier materials preventing permeation of volatile gases by creating a long path for diffusion and as flame-retardant materials. Previous work mainly involves the utihzation of cationic clays, although LDH materials... 

J. M. Herrera-Alonso, E. Marand, J. C. Little, S. S. Cox, Transport properties in polyurethane/ clay nanocomposites as barrier materials Effect of processing conditions, J. Membr. Sci., 337, 208-214 (2009). 

The arrangement of the layers themselves also has an impact. The self-extinguishing properties of these materials, for instance, have been described qualitatively. A protective char layer forms and acts as a diffusion barrier to further combustion. Likewise, before the advents of nanocomposites, models of the barrier properties of glass-ribbon reinforced composites foreshadowed the increased tortuosity arguments often heard with regard to nanocomposite barrier properties. Improvements on these first approximations of bar-... 

In 2001, Honeywell marketed a nanoclay/polyamide 6 material imder the name Aegis with nanoclay supplied by Nanocor. Fiat is now using polyamide-based nanocomposite barrier layers in its vehicle fuel lines. 

There are numerous other possible packaging combinations. Materials such as PET, polyamides and polypropylene are coated with silicon or aluminium oxide to create barriers for oxygen and organics. Clay-polyimide nanocomposites have been evaluated as barrier materials for oxygen, carbon dioxide and water vapour. 

Under specific experimental conditions, such materials may be obtained as delaminated (or exfoliated) nanocomposites, which may be described as single inorganic slabs imiformly and randomly dispersed within a polymer matrix. Readers interested by the synthesis and the properties of these delaminated nanocomposites, especially in the field of clays, should see Nanocomposites, Polymer-Clay and other recent reviews (7-9). These materials have imusual and versatile properties, such as barrier materials and reinforced materials, (see Barrier Polymers Reinforcement). 

One potential area of application where CNs can be used extensively is in the field of high-performance nanocomposite packaging materials. The rod-shaped nanocrystals are known for reinforcing polymeric materials however, not much information is available about their efficacy as barrier materials. Research in this area is evolving rapidly to enhance both mechanical and barrier properties of... 

Potential of polymer-clay nanocomposites as barrier materials... 

In the previous pages, several examples of new barrier materials based on nanocomposites of polymers and layered silicates have been presented. The... 

In conclusion, due to the unique combination of their key properties and potentially low production costs, polymer nanocomposites have opened new technological dimensions in the development of efficient and low cost barrier materials. 

PI nanocomposites have been prepared by various methods with different fillers. The nanocomposites might have many applications starting from barrier and thermal resistance to a compound with low coefficient of thermal expansion (CTE) [154-167]. These hybrid materials show very high thermal and flame retardation as well as barrier resistance and adhesion. Tyan et al. [158] have shown that depending on the structure of the polyimide the properties vary. Chang et al. [159] have also investigated the dependency of the properties on the clay modifiers. 

It is likely that excellent gas barrier properties exhibited by nanocomposite polymer systems will result in their substantial use as packaging materials in fumre years. 

Above we have shown the attractiveness of the so-called green nanocomposites, although the research on these materials can still be considered to be in an embryonic phase. It can be expected that diverse nano- or micro-particles of silica, silicates, LDHs and carbonates could be used as ecological and low cost nanofillers that can be assembled with polysaccharides and other biopolymers. The controlled modification of natural polymers can alter the nature of the interactions between components, affording new formulations that could lead to bioplastics with improved mechanical and barrier properties. 

I, H. Tseng, Y. F. Liao, J. C. Chiang, M. H. Tsai, Transparent polyimide/graphene oxide nanocomposite with improved moisture barrier property., Materials Chemistry and Physics, vol. 136, pp. 247-253, 2012. 

Nevertheless the euphoric optimism where these materials were allowed a huge potential in material applications has given way to a more realistic view. Nanocomposites are not a universal solution for reinforced materials. Their full potential can only be realised if every step in the added value chain is taken into account during the whole development process. From todays perspective nanocomposite materials with an improved thermal flammability resistance or improved barrier properties have the best chances to fulfil these requirements. 

Polymer-clay nanocomposites (PCN) are a class of hybrid materials composed of organic polymer matrices and organophilic clay fillers, introduced in late 1980s by the researchers of Toyota (Kawasumi, 2004). They observed an increase in mechanical and thermal properties of nylons with the addition of a small amount of nano-sized clays. This new and emerging class of pol miers has found several applications in the food and non-food sectors, such as in constmction, automobiles, aerospace, military, electronics, food packaging and coatings, because of its superior mechanical strength, heat and flame resistance and improved barrier properties (Ray et al., 2006). 

Park, H.W., Lee, W. K.,Park, C. Y.,Cho, W. J., Ha, C. S. (2003). Environmentally friendly polymer hybrids Parti. Meehanical, thermal, and barrier properties of thermoplastie stareh/elay nanocomposites. Journal of Materials Science, 38, 909-915. 

The most important materials developed are nanocomposites and nanotubes. Fabrication of the first nanocomposites was inspired by nature (biomineralisation). Nanocomposites based on nanoclays and plastics are seen as ideal materials for improved barrier properties against oxygen, water, carbon dioxide and volatiles [37]. This makes them in particular suitable for retaining flavours in foods. The technology is rather straightforward using commercially available nanoclays and extrusion processing. 

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