Abstract:

Combined microwave and ultrasonic treatments was used to prepare zein/chitosan composite films. The
optimization of process parameters was carried out using one-factor-at-a-time and orthogonal array. The independent
variables were ultrasonic power, microwave heating temperature and combined treatment,time, and stirrer speed, and
the response was film tensile strength. The optimum process parameters were determined as follows: ultrasonic power,
180 W; microwave heating temperature, 50 ℃; combined treatment time, 6 min; and stirrer speed, 300 r/min. Under these
conditions, the tensile strength of composite films was (19.98 ± 0.34) MPa. Scanning electron microscopy (SEM) showed
that the combined microwave-ultrasonic treatments could obviously improve the microstructure of composite films apart
from smooth surface with less roughness. Infrared spectral analysis indicate that the original molecular structure was not
significantly damaged.

Key words: combined microwave and ultrasonic treatment, composite films, optimal conditions, morphological analysis