Blends of Polyhydroxyalkanoates (PHAs) - Polyhydroxyalkanoate (PHA) Based Blends, Composites and Nanocomposites - page 76

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Figure 4.2 (A) Visual image (left), PLA-specific FT-IR image (center), and P(3HB)-

specific FT-IR image (right) of a P(3HB)/PLA: 50/50 wt% blend. (B) Visual
image (left), PLA-specific FT-IR image (center), and P(3HB)-specific FT-IR
image (right) of a P(3HB)/PLA: 30/70 wt% blend. 59

modulus might be because of the high strength and modulus of the PLA
phase. It was also reported that there was a good transfer of stress from
one phase to another in the blend. However, Zhao et al. 23 reported that in-
creasing the P(3HB-co-3HV) copolymer content from 0 to 45% reduced
the tensile strength of P(3HB-co-3HV)/PLA blends from 54.99 to 42.23 MPa.
It was also reported that this might be because of the P(3HB-co-3HV) co-
polymer, which had relatively low tensile strength and relatively weak poly-
mer interfaces.
Noda et al. 61 reported that the addition of 10% PHA to PLA increased the
elongation of the blend due to the presence of the amorphous phase of the
blend. The same trend was reported by Nanda et al. 22 whereby the elongation
of all P(3HB-co-3HV)/PLA blends were more than the neat polymers. Max-
imum elongation was observed for the P(3HB-co-3HV)/PLA: 60/40 wt% blend,
where the elongation was reported to be 148 and 250% more than the neat
P(3HB-co-3HV) copolymer and PLA, respectively. Zhao et al. 23 also reported
that the strain at break increased as the P(3HB-co-3HV) copolymer was in-
corporated into the PLA. The impact strength of neat PLA was recorded
as 30 J m 1 and for neat P(3HB-co-3HV), it was 49 J m 1 . Although the
elongation at break reported for the P(3HB-co-3HV)/PLA blend was
higher than the individual polymer, the impact strength, however, was
nearly equal to that of the PLA. 22 Zembouai et al. 24 reported that the Young's
modulus decreased as the amount of PLA increased. It was also reported
that for the blends P(3HB-co-3HV)/PLA: 75/25 wt% and 50/50 wt%, the
elongation at break was lower than for the neat PLA. However, for the blend

.