Table 1 shows the processing parameters, i.e. induced pressure
and torque as well as the output rate, for compounding
extrusion and blown film extrusion of TPS and TPS/CTS materials.
For films produced by the compounding process using a
twin-screw extruder, TPS possessed induced pressure of 24–35 bar,
while TPS/CTS compounds exhibited higher induced pressure, in
the range of 35–65 bar. The induced pressure of the TPS/CTS compounds
increased with increasing chitosan concentration, implying
that the material became viscous, probably due to the interaction
or entanglement between starch and chitosan molecules. Although
the induced pressure became higher as chitosan content increased,
extrusion of the TPS/CTS compounds could be performed without
any difficulty as the torque of the system remained essentially
unchanged. In addition, the increased induced pressure provided
not only easier processing but also a greater output rate of the
products (Table 1). The output rate of TPS/CTS compounds was
almost twice as high as that of TPS when 1.45% of chitosan was
incorporated.