**6. Conclusions**

finally to a solid-like response with G' > G" in all frequency ranges, as seen in **Figure 16**. The number of particles per unit volume is a key factor determining the characteristic response of

The presence of nanofillers caused these nanocomposites to have solid-like behaviors and slower relaxation. This behavior can be explained in terms of the development of a graftingpercolated nanoparticle network structure [105]. Its formation is a consequence of physical interactions between dispersed nanoparticles, polymeric chains and surfactants, which pro-

The next section will briefly discuss the main properties and characteristics of some polymer

Polymer nanocomposites have advantages: (1) they are lighter than conventional composites because high degrees of stiffness and strength are realized with far less high-density material, (2) their barrier properties are improved compared with the neat polymer, (3) their mechanical and thermal properties are potentially superior and (4) exhibit excellent flammability

There are many applications of polymer/clay nanocomposites and an increasing number of commercial products available on the market. Notable examples are automotive parts [16, 20], packaging [2, 8, 107], construction materials [36], biotechnology [108], medical devices, etc. [3, 36, 108]. One important property observed due to the incorporation of clay particles in polymers is a significant level of flame retardancy. This property also provides avenues for applications in many other areas, such as building materials, computer housings and car interiors [36]. Moreover, balanced mechanical properties, functionalities and biocompatibility of bionanocomposites provide an exciting platform for the design and fabrication of new materials for biomedical applications [36]. Another area of interest for nanocomposites is the packaging industry. The impermeable clay layers mandate a tortuous pathway, which difficult the diffusion of molecules throughout the matrix [109]. Improving food quality and shelf life, while reducing plastic waste, has stimulated the development of biodegradable

There are also several applications with carbon nanotubes and graphene. An area of notable application of these materials is in the optoelectronic industry [110, 111]. There is a wide range of applications which include fiber lasers, supercapacitor, field emission devices and photovoltaics, where the combination of tunable optoelectronic properties as well as structural and chemical stability, high surface area and low mass density of nanofillers with the

Nanocomposites of an organic-modified MMT and PA6 with a residual monomer were once produced by melt blending in a torque rheometer [112]. By WAXD, intercalated structures were observed in the nanocomposites with 3 and 5 wt% of MMT; on the other hand,

mote a considerable resistance to flow [103]. This behavior is shown in **Figure 17**.

properties and increased biodegradability of biodegradable polymers [106].

polymer-based PCNs as advanced and smart packaging materials [109].

processability of polymers offers a new class of materials [110, 111].

nanocomposites, which have been used in relevant applications.

**5. Properties and potential applications**

nanocomposites [82, 104].

118 Nanocomposites - Recent Evolutions

Polymer nanocomposites offer excellent opportunities to explore new functionalities beyond those of conventional materials. The field of nanocomposites has been one of the most promising and emerging research areas. They find special attention due to the unique properties such as light weight, ease of production and flexibility. A defining feature of polymer nanocomposites is that the small size of the fillers leads to an enormous increase in interfacial area as compared to traditional composites. The interfacial area creates a significant volume fraction of interfacial polymer with properties different from the bulk polymer even at low loadings of the nanofiller. Interfacial structure is known to be different from bulk structure, and in polymers with nanoparticles possessing high surface areas, most parts of the polymers are present near the interfaces, in spite of the small weight fraction of the filler. This is one of the reasons why the nature of reinforcement is different in nanocomposites. The crucial parameters which determine the effects of fillers on the properties of composites are filler size, shape and aspect ratio and filler-matrix interactions.
