Page 283 - Biodegradable Polyesters

10.2 Polylactide Strengthening and Strategies 261

SEBS-g-MA
SEBS-g-MA
Encapsulated MMT

MMT silicate layer
MMT silicate layer
(a) 500 nm (b) 500 nm

Figure 10.19 Morphologies of PLA/MMT (98/2wt/wt%) nanocomposites containing 5 phr
(a) and 20 phr (b) of SEBS-g-MA. Reproduced with permission from Ref. [170] © 2011, John
Wiley and sons.
the presence of 10 wt% of wood and 25 wt% of PHAs within PLA-based blends.
Hybrid biocomposites composed of surface-modified jute fiber and varying
weight fractions of PLA and PCL were introduced by Goriparthi et al. [174],
resulting in improvement of impact strength and damping capacity without sub-
stantial sacrifice in stiffness and strength. Hasook et al. [175] investigated effects
of PCL molecular weight on mechanical properties of ternary PLA/PCL/MMT
composites to give the best combination of overall properties at 5 wt% of PCL
and 5 wt% of MMT. This ternary composite displayed increases in tensile
strength of 20%, in elastic modulus of 10%, and in ultimate elongation of 50%
with respecttoneatPLA.Teamsinsungvon et al. [176] reinforced PLA/PBAT
blends using microsized precipitated calcium carbonate and achieved similar
toughening effects on PLA/PBAT (80/20 wt/wt%) blends. Finally, the effects
®
®
of two types of organoclays (Cloisite 30B and Cloisite 20A), two types of
core–shell rubbers (polybutylacrylate-polymethylmethacrylate-based Paraloid
EXL2330 and EXL2314) and the combination of related nanoclay and rubber
on the mechanical properties of the PLA-based composites were investigated
®
by Li et al. [177]. The simultaneous addition of 5 wt% nanoclay (Cloisite 30B)
and 20 wt% EXL2330 resulted in a PLA-based composite with a 134% increase
−2
in notched Izod impact strength (5.15 kJ m ) and a similar modulus (1.8 GPa) in
comparison with neat PLA.
10.2.4
Interpenetrating Networks and Self-Assembling of PLA-Based Materials

An Interpenetrating network is defined as a blend in which one or more polymers
are intimately cross-linked and one or more polymers are linear or branched.
In this field, recent studies indicate that hyperbranched polymers (HBPs) may