As cellulose, cellulose derivatives undergo thermo-oxidative
degradation at high temperatures [25]. The decomposition temperature
of CA2.5 is close to its softening point and it is thus
necessary to blend this polymer with a plasticizer in order to obtain
cellulose acetate materials of suitable flow properties [26]. Plasticization
also permits to process this material at slightly lower
temperatures, which dismiss coloration due to degradation phenomena.
Furthermore, the biodegradability of CA2.5 is effectively
enhanced by plasticizitation with environmentally-friendly plasticizer
as triacetin [27,28]. Plasticization of CA using triacetin (30 wt
%) was carried out using a twin screw extruder. The plasticizers
were introduced through the third barrel zone under the control of
a liquid feeder. The extruder temperature profiles utilized for
plasticization are summarized in Table 1. Processing parameters
were optimized in order to increase the extruder throughput and to
obtain extruded products with good visual appearance. Indeed,
pellets exhibiting great clarity and transparency and negligible
coloration were produced at 4e5 kg/h using a screw speed of
250 rpm. Plasticizer content on extruded materialswas determined
by thermogravimetric analysis (TGA) under nitrogen atmosphere
(thermograms not shown). A triacetin content of 30 ± 2 wt% has