Box–Behnken design was successfully employed for the experimental
design and analysis the mechanical properties of the films
formulated from tapioca starch, glycerol, agar, and span 80. The
films were uniform, flexible and transparent. The results showed
that, the glycerol was the most important parameter influencing
the mechanical properties of the films, due to its plasticizing effect
on the polymer matrix. Analysis of variance showed a high coefficient
of determination value (R2) of 0.995 for tensile strength, 0.998
for elongation, 0.999 for Young’s modulus, 0.997 for puncture force,
and 0.973 for puncture deformation, thus ensuring a satisfactory fit
of the second order polynomial regression model with the experimental
data. The models obtained in the experimental design were
predictive, which was evidenced by the relative deviations of less
than 5% in validation procedure.