Quantification of Nanoassembly Exfoliation

The exact number of clay stacks having the above three categories of platelet stacking were measured by taking at least six different HRTEM images for each type of nanocomposite sample and the average distribution of the clay platelets were noted down (Fig. 38). This has been represented as the extent of exfoliation (B) in Table 9. It is apparent that as the level of exfoliation increases, the number of clay platelets per stack decreases and their effective surface area contribution increases. 

In order to quantify the level of exfoliation, a surface area factor (SAF) has been proposed, which is the sum of the numerical products of A and B, as defined above. 

Number of clay platelets per stack Effective surface area contribution of clay platelets (A) Extent of exfoliation in nanocomposite sample as obtained from image analysis ( )  

The increment in mechanical properties (tensile strength, 300% modulus, and Young s modulus) as a function of SAF is plotted in Fig. 39. In general, the higher level of SAF, which in turn indicates better exfoliation, results in high level of property enhancement. However, the level of increment with the increase in SAF is different in all three cases and follows a typical exponential growth pattern. The apparent nonlinear curve fitting of the experimental values presented in Fig. 39 is a measure of the dependence of mechanical properties on the proposed SAF function. 

The relationship between the SAF and the percentage increment in the respective property can be mathematically represented as  

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