Similarly, TPS/CTS compounds also exhibited higher induced
pressure during blown film extrusion (168–204 bar) compared
with TPS (121–135 bar) (Table 1), corresponding to the higher
blown film production rate (data not shown). The torque ofthe system
tended to increase with increasing chitosan concentration due
to the increasedmelt viscosity or decreasedflow ability.It should be
pointed out that although both TPS and TPS/CTS compounds could
be continuously blown into films (Fig. 1A), the obtained TPS/CTS
films possessed tunable thickness due to their higher melt strength.
In addition, the TPS/CTS films had reduced surface stickiness and
greater opacity (Fig. 1Ab) as compared with TPS film (Fig. 1Aa).
Melt flow behavior of TPS and TPS/CTS compounds was evaluated
from the melt flow index (MFI), measured at 190 ◦C with
a load cell of 3.2 kg. MFI value of TPS was about 1.32 g/10 min,
while those of TPS/CTS compounds varied from 0.09 g/10 min to
0.81 g/10 min (Fig. 1B). The results showed that the melt flow ability
of TPSdecreased, or itsmelt viscosity increased, by incorporating
chitosan. In addition, the melt flow ability significantly decreased
with increasing chitosan content: for example, by almost three
times for TPS/CTS0.73 as compared with TPS/CTS0.37. The reduction
of melt flow ability might result from the interaction between
starch and chitosan molecules.