Figure 5 shows the effect of the processing temperature
ranging from 145 to 165 o
C on the cellular structure of the PLA
foamed samples. A few cellular structures were formed owing
to the unsaturated foaming temperature (145 o
C). A collapsed
cellular structure was observed at 165 o
C because the
melt viscosity was too low for stabilization of the foamed
structure, which was due to the lowered melt temperature of
PLA by dissolution of CO2 gas
the viscosity of the PLA/CNF (5 wt%) nanocomposite
decreased rapidly even from the highest initial viscosity,
which may have been cause by the tendency of the CNFs at
high content to agglomerate into larger aggregates and induce a