To improve overall strength of composite materials, the reinforcement
must be distributed as small domains and embedded
with a good interfacial adhesion to the PBS matrix. Thus, SEM
was employed to study the fracture morphology of composite films
and clearly shown in Fig. 1. White spots indicated the dispersed
ZnO particles in PBS matrix. It was clearly seen that ZnO particles
were homogeneously dispersed by around 100 nm in PBS matrix
from 2 to 6 wt%. Beyond these concentrations, some aggregations
around 0.5–1 lm were observed. This was believed to facilitate
the stress transfer when the tensile load was applied. The relatively
rough fracture surface with greater amount of localized plastic
deformation of the neat PBS in Fig. 1(a) suggested that the PBS fractured in a ductile fashion under impact force. With the presence
of ZnO, PBS had smoother fracture surface implying that the
crack progressed rapidly with only small amount of energy
absorbed before failure [18]. This was the cause of the reduction
of the impact strength.