**4. Methods used for the synthesis of nanocomposites**

Several methods were reported to prepare clay-based polymer nanocomposites. These include in-situ polymerization, melt intercalation, and solution casting, according to the starting materials and processing techniques:

Concerning the characterization of polymer-clay nanocomposites, the small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) are the main techniques used to identify the structure of nanocomposites. Indeed, the SAXS allows to monitor the position, shape, and the intensity of the peak, while TEM provides information on the spatial disposition of the internal structure and the spatial distribution of the various phases. SEM is employed to identify the response of the clays to the

**Processing methods Advantages Limitations**

polarity

process

methods

Melt intercalation • Environmentally benign

• More suitable at laboratory scale • Uniform dispersion of the clay particles inside the polymer

• Preparation of intercalated nanocomposites based on polymers with low

• Easy method, based on the dispersion of the filler in the liquid monomer

• Compatible with industrial polymer

• Use of polymers not suited for other

**Table 2.** Summary of different methods used for the synthesis of nanocomposites.

• Environmentally unfriendly due to the use

• Limited to certain polymer/solvent pairs, in which the polymer is soluble and the

• Monomer and clay must have similar

• Suitable monomer is not always available

of large amounts of solvents

Polymer-Clay Nanocomposites for Corrosion Protection http://dx.doi.org/10.5772/intechopen.74154 67

silicate layers are swellable

hydrophobicity to mix • Limited applications

• Difficult control of intragallery

• Limited applications to polyolefins • Organo-modified clay must be thermally stable at the softening point of the polymer

polymerization

Corrosion is defined as the gradual oxidation of metallic materials by converting them to their original state of oxide, sulfide, carbonate, or other stable salts in the ambient environment. Corrosion results from a combination of reactions occurring at the metal-solution interface by involving electrons and the chemical species. More specifically, the oxidation of the metallic material naturally occurs at the metal-environment interface and constitutes the anodic reaction, whereas the reduction of oxygen typically takes place in solution and often constitutes the cathodic reaction [44]. The cathodic and anodic reactions form an electrical circuit, which is completed by conduction of electrons in the metal and by ionic conduction through the electrolyte. There are various forms of corrosion that can take place depending on the surrounding environment and the design of the equipment that suffers corrosion. The galvanic, pitting, intergranular, crevice, and uniform corrosions are the most investigated corrosion

cationic exchange reaction.

Intercalation of polymer

In-situ intercalative polymerization

from solution

**5. Corrosion and organic coatings**



**Table 2.** Summary of different methods used for the synthesis of nanocomposites.

Concerning the characterization of polymer-clay nanocomposites, the small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) are the main techniques used to identify the structure of nanocomposites. Indeed, the SAXS allows to monitor the position, shape, and the intensity of the peak, while TEM provides information on the spatial disposition of the internal structure and the spatial distribution of the various phases. SEM is employed to identify the response of the clays to the cationic exchange reaction.
