Page 281 - Biodegradable Polyesters

10.2 Polylactide Strengthening and Strategies 259

improving the interfacial adhesion of the PLA/LLDPE blend matrix distinctly
and refining the dispersed phase (Figure 10.17).
Compatibilization-like effect of reactive organoclay (Cloisite ® 25A treated
with (glycidoxypropyl)trimethoxysilane) on the PLA/PBS blends was reported
by Chen et al. [164]. The clay layers became fully exfoliated and were located
mainly in the PLA phase at low clay concentration, while the clay layers were
dispersed in both the PBS and PLA phases at high concentration. This change of
clay location sharply decreased the size of the dispersed PBS phase and improved
the mechanical performances of the resulting PLA-based nanocomposites.
Analogous trends were observed by the same authors for PLA/PBSA/epoxy–clay
blends [165]. Again, it was shown that the dispersed particle sizes decreased
with increasing epoxy–clay content, consistent with a compatibilization process.
Another investigation by Wen et al. [166] regarding PLA/silica nanocomposites
containing hyperbranched poly(ester amide) highlighted an encapsulation
structure formed by the hyperbranched polymer (HBP) surrounding silica
nanoparticles (Figure 10.18). This phase microstructure highly improved the
miscibility between the polymer matrix and nanofiller, strengthened the interface
adhesion as a result and promoted a sixfold increase in notched Charpy impact
strength (26.8 kJ m −2 for PLA containing 3 wt% of silica and 7.5 wt% of HBP com-
pared to 4.5 kJ m −2 for pure PLA). Similarly, Baouz et al. [167] used organoclay at

(a) 100 nm (b) 500 nm

100 nm
(c) 500 nm (d)
Figure 10.18 Morphologies of PLA-based materials containing 3 wt% of SiO (a), 7.5 wt% of
2
HBP (b) and 3 wt% of SiO together with 7.5 wt% (c, d) of HBP. Reproduced with permission
2
from Ref. [166] © 2010, John Wiley and sons.