Nanocomposites of Polyhydroxyalkanoates (PHAs) - Polyhydroxyalkanoate (PHA) Based Blends, Composites and Nanocomposites - page 104

higher increase in nanofiller loading (45%) does not improve the mentioned
mechanical properties. 32
Zhijiang et al. 42 reported an improvement in the mechanical properties of
a PHB nanocomposite made of bacterial cellulose nanofibrils that was pre-
pared by the solution casting method. In addition, they found that the
nanocomposite showed better biocompatibility and mechanical properties
than pure PHB based on cell-adhesion analysis using Chinese hamster lung
(CHL) fibroblast cells and stress strain tests, respectively. 42 In comparison to
pure PHB, the nanocomposite of PHB/bacterial cellulose was observed to
exhibit about a 202% increase in tensile stress and a 2.2-fold increase in
elongation to break, respectively (Figure 5.3). 42
The same solution casting method was employed in the authors' labora-
tory to study the degradation behavior and thermo-mechanical properties
of nanocomposites based on medium-chain-length PHA/carbon nanofibers
(CNF) in an ultrasound assisted process. At CNF loading r 10% w/w, a cor-
relative increase in the nanofiller dispersion with increasing sonication
power output and exposure time was observed. This led to the formation
of an exfoliated nanocomposite. In contrast, when the CNF nanofiller
loading was increased beyond 10% w/w, a nanocomposite with agglomer-
ated morphology was observed. Ten et al. 44 studied the isothermal crystal-
lization kinetics of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

d n 2 r 4 n g | 8

(PHBV)

.

Figure 5.3 Comparison of tensile test results on (a) PHB and (b) a PHB/bacterial
cellulose nanocomposite.
Reprinted from Zhijiang et al. 42 with permission from Elsevier.