the increase in CSR content, both the flexural modulus
and the flexural strength dropped, reaching their minimum
values at 2.33 GPa and 61.57 MPa respectively
when the CSR content reached 10 wt%. Microscopic
observation by SEM was employed to observe the
fracture morphology of the blends, as illustrated in Fig. 1.
The micrograph in Fig. 1a illustrates that polylactic acid fractured
in a brittle fashion as demonstrated by its smooth fracture
surface. With greater CSR content, the fracture
surfaces of the polylactic acid blends showed more localized
plastic deformations induced by the CSR. In Figs.
1b–1g, CSR particles were dispersed and embedded
quite well within the polylactic acid matrix. Fig. 1h confirmed a
good interfacial adhesion between the polylactic acid matrix and
the CSR particles, leading to significant improvement of
the toughness when CSR was incorporated. Base on the
mechanical test results, 5 wt% of CSR seemed to be the
most appropriate composition for toughening the polylactic acid
matrix for the preparation of the WPC. The 5 wt% CSR
was selected as there was no remarkable difference
between its toughness (in terms of impact strength and