Comparing Fig. 8(a) and (b), it is noted that the apparent scattering
intensities of the fractured samples are much larger than
those of the un-deformed counterparts. The plot of relative scattering
intensity has clearly shown this in Fig. 9. The relative scattering
intensity is increased from 3.16 for the un-deformed
specimen with 2.0wt% nanofillers to 17.38 for the fractured specimen
with the same loading of nanofillers. Except for the scattering
from nanoparticles, the extra scattering in the fractured specimens
comes mainly from the microcracks, crazes, and microvoids formed
through nanoparticles debonding from the matrix as shown in
Fig. 10. Obviously, the addition of nanofillers has greatly promoted
the formation of microcracks, crazes and microvoids, which
contribute to the improvement in impact strength and fracture
toughness of the silica-P(CL-mLA)-COOH toughened epoxy.