Elastic moduli of clay platelets

We survey estimates of elastic moduli of smectite clay platelets required for the theoretical understanding of polymer–clay nanocomposites. Experimental measurements have been unsuccessful, so it is presently not possible to calculate absolute values of modulus for use in composite theory. We focus on analogous minerals and modulus–density relations to deduce a convergence of opinion in the range 178–265 GPa. The use of this range in the prediction of polymer–clay nanocomposite modulus does not introduce significant error provided the platelet volume fraction is below 0.3. Current nanocomposites have volume fractions <0.1.