Nanocomposite barrier

Fiat projects new applications for nanocomposites in the form of PA fuel lines incorporating PA nanocomposite barrier layers from Ube. 

Nanocomposites are new entrants to the packaging arena. Ube industries in Japan, in collaboration with Toyota, has developed nanocomposite barrier films for food packaging and other applications. 

Nanocomposite Barrier Materials with Novel Functionalities... 

Work done by Gong et al. [66] is similar to the work by Maruyama et ah, above. They functionalize butyl rubber with succinic anhydride to improve the compatibility of butyl rubber with an organoclay. Barrier performance of the rubber nanocomposite increases with the amount of succinic anhydride modification. In a companion publication [67], butyl rubber is functionalized by grafting maleic anhydride onto the polymer chain with peroxide. The same organoclay is utilized in this work as well to form the rubber nanocomposite. Barrier performance of the butyl rubber is significantly enhanced. 

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. 

Comparison of experimental observations with barrier model predictions clearly indicated that increase of clay content has an impact on effective clay aspect ratio and alignment, which in turn affect the nanocomposite barrier properties. At the same time, the barrier models could serve as indirect tools for quantification of the degree of exfo-liation/intercalation/aggregation in the production nanocomposite prodncts. 

Dunkerley Erik J, Schmidt Daniel F. Expanding the range of nanocomposite barrier properties measurement and modeling. In MRS fall meeting exhibit, November 28-December 2, 2011, Boston, Massachusetts 2011. 

Nanocomposite based on polyurethane (PU) is prepared using silica, clay, and Polyhedral Oligomeric Silsesquioxane (POSS). Preparation, characterization, mechanical and barrier properties, morphology, and effect of processing conditions have been reported on polyurethane-based nanocomposites [72,73]. 

Nanocomposites have been prepared with this polymer and mechanical and barrier properties and ffacmre behavior have been studied [74—76]. The latex of this mbber has also been used for the same [77]. Sadhu and Bhowmick [78-81] have studied the preparation, stmcmre, and various... 

This is a highly polar polymer and crystalline due to the presence of amide linkages. To achieve effective intercalation and exfoliation, the nanoclay has to be modified with some functional polar group. Most commonly, amino acid treatment is done for the nanoclays. Nanocomposites have been prepared using in situ polymerization [85] and melt-intercalation methods [113-117]. Crystallization behavior [118-122], mechanical [123,124], thermal, and barrier properties, and kinetic study [125,126] have been carried out. Nylon-based nanocomposites are now being produced commercially. 

PP is probably the most thoroughly investigated system in the nanocomposite field next to nylon [127-132]. In most of the cases isotactic/syndiotactic-PP-based nanocomposites have been prepared with various clays using maleic anhydride as the compatibilizer. Sometimes maleic anhydride-grafted PP has also been used [127]. Nanocomposites have shown dramatic improvement over the pristine polymer in mechanical, rheological, thermal, and barrier properties [132-138]. Crystallization [139,140], thermodynamic behavior, and kinetic study [141] have also been done. 

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. 

Owing to the good barrier property, the EVA-based clay nanocomposites are used for packaging, bottle-making, etc. [168]. 

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. 

Rubber-clay nanocomposites are particularly attractive for potential applications where enhanced barrier properties are desired. Organoclays for rubber intercalation were prepared... 

Polyimide-clay nanocomposites constitute another example of the synthesis of nanocomposite from polymer solution [70-76]. Polyimide-clay nanocomposite films were produced via polymerization of 4,4 -diaminodiphenyl ether and pyromellitic dianhydride in dimethylacetamide (DMAC) solvent, followed by mixing of the poly(amic acid) solution with organoclay dispersed in DMAC. Synthetic mica and MMT produced primarily exfoliated nanocomposites, while saponite and hectorite led to only monolayer intercalation in the clay galleries [71]. Dramatic improvements in barrier properties, thermal stability, and modulus were observed for these nanocomposites. Polyimide-clay nanocomposites containing only a small fraction of clay exhibited a several-fold reduction in the... 

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. 

Most nanocomposite researchers obdurately believe that the preparation of a completely exfoliated structure is the ultimate target for better overall properties. However, these significant improvements are not observed in every nanocomposite system, including systems where the silicate layers are near to exfoliated [29]. While, from the barrier property standpoint, the development of exfoliated nanocomposites is always preferred, Nylon 6-based nanocomposite systems are completely different from other nanocomposite systems, as discussed [3,8]. 

In 2002, Lee et al. [51] reported the biodegradation of aliphatic polyester-based nanocomposites under compost. Figure 9.13(A, B) represent the clay content dependence of biodegradation of APES-based nanocomposites prepared with two different types of MMT clays. They assumed that the retardation of biodegradation was due to the improvement of the barrier properties of the aliphatic APSE after nanocomposite preparation with clay. However, there are no data about permeability. 

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