Nanoclay advantages

Thorough study of nanocomposites has revealed clearly that nanoclays can provide certain advantages in properties in comparison to their conventional filler counterparts. Properties which have been shown to undergo substantial improvements include ... 

The use of nanoclays in conventional polymer nanocomposites is well known and diffuse. The advantages of the addition of nanoclays to a polymeric matrix are the improvement of mechanical properties, the enhancement of barrier effect, and the increase of chemical and thermal stability. 

Sodium montmorillonite (Na-MMT) was originally modified with pro-tonated amino acids with different numbers of carbon atoms and subsequently swollen with e-caprolactam. Then it underwent polymerization to produce nylon-6 polymer-clay nanocomposite [18]. Later, this technique was also extended to manufacture other thermoplactics. One advantage of this in-situ polymerization technique is the tethering effect, which enables the organic chemical such as 12-aminododecanoic acid (ADA) situated at the surface of the nanoclays to link with nylon-6 polymer chains during polymerization. 

This chapter reviews the use of the sepiolite/palygorskite group of clays as a nanofiller for polymer nanocomposites. Sepiolite and palygorskite are characterized by a needle-like or fiber-like shape. This peculiar shape offers unique advantages in terms of mechanical reinforcement while, at the same time, it allows to study the effect of the nanofiller s shape on the final composite properties. The importance of the nanofiller shape for the composite properties is analyzed in Section 12.2, introducing the rationale of the whole chapter. After a general description of needle-like nanoclays in Section 12.3, the chapter develops into a main part (Section 12.4), reviewing the preparation methods and physical properties of polyolefin/needle-like clay nanocomposites. 

Sud-Chemie has developed a new series of flame retardants in collaboration with Alcan Chemicals. These are a combination of Alcan s inorganic Flamtard AN and Siid-Chemie s nanoclays that offer advantages for the cable sector such as a lower dosage and higher extension output compared to existing products. 

In the melt mixing method, nanoclays are incorporated into the polymer in the molten state. This technique has considerable advantages over either the in situ intercalative polymerization or polymer solution intercalation techniques. Firstly, this method is environmentally benign due to the absence of organic solvents. Secondly, melt processing is compatible with current industrial processes, such as extrusion and injection moulding. The melt intercalation method allows the use of biopolymers that were not suitable for in situ polymerization. This has been the most widely used method in the literature for obtaining PLA/clay nanocomposites. " ... 

This is an area where the nanoclays appear to offer very distinct advantages and is already undergoing commercialisation. Thns, as little as 2 wt% of a nano-clay is sufficient to decrease the oxygen transmission rate of a polyamide film by over 40%. Their performance is believed to be due to the creation of a tortuous diffusion path, as shown in Figure 10.8. (Note alignment is necessary for this. Truly random dispersion would not give the same effect). 

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