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exfoliation & dispersion
Exfoliation is achieved when the individual montmorillonite platelets no longer exhibit an XRD deflection. Generally, we can assume that the absence of clay peaks in the XRD spectra indicate that the platelets are at least 70 angstroms apart. When this condition is achieved, the promised surface area is exposed and high aspect ratios gained.
The condition has been observed where XRD patterns indicate exfoliation, but areas within the composite are said to be resin rich, i.e. the absence of homogeneously dispersed montmorillonite. The conclusion is that the aggregates of montmorillonite must be exfoliated into primary platelets, and these platelets must be distributed throughout the polymer matrix homogeneously.
The TEM figure below illustrates both conditions of exfoliation and dispersion of Cloisite® into Nylon 6.
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