XRD is very sensitive at low angles 2θ, which is the critical
area for determining the interlayer spacing. Therefore,
the absence of peaks does not mean that exfoliation is
completely achieved but that they are intercalated due
to large spacing. TEM provides a most direct way to
examine the states of clay exfoliation as this technique
can image materials on the nanometer scale. The states
of clay exfoliation, such as whether the clay is intercalated
or exfoliated, can be observed directly. Wetzel13 used
TEM technique to visualize the dispersion quality of
nanoparticles. He founded homogeneous distribution
of nano particles with some small agglomerates in the
matrix. TEM micrographs in Figure 1 conforms the
uniform distribution of nanosilica in Epikote 8286. There
was no agglomeration of the SiO2 nanoparticles even at
high volume fraction.