In relation with WG-based bioplastics, three different regions
may clearly be distinguished in the reference (0 wt.% formic acid)
sample: (a) during the 15 first minutes, approximately, torque does
not increase significantly, as this region stands for an induction
period, which was seen to decrease as mixing speed was raised
(not shown here); (b) in the second region, which extends over a
time interval of 5 min, torque undergoes an exponential increase
up to a maximum value of about 40 N m; and (c) torque finally decays,
whilst seems to tend to a constant value. Analogously, three
different zones have also been identified from the sigmoid function
which relates temperature and time: (a) a nearly isothermal step;
(b) a further exponential increase up to 65 C; and (c) a very slight
increase in temperature, which corresponds to the final torque
decay.