The effect of moist heat treatment on the characteristic of starch-based composite materials coating with chitosan

The starch-based composite material (STM) was prepared with cassava starch and modified cellulose and coated with chitosan to obtain better hydrophobic and heat-resistant properties. The hydrogen bond interactions between chitosan and basic material were proven by FTIR. By the SEM analysis, the blends showed a good compatibility and the cavities in STM was repaired and smoothed after coating. From the results of polarized optical microscope, AFM and positron annihilation lifetime spectroscopy, coating the STM with chitosan decreased the free volume of uncoated STM after moist heat treatment, the amorphous regions of the latter absorbed water more easily than the former. The mechanical properties of uncoated STM were inferior to the coated STM. Furthermore, chitosan coating decreased the gain weight and slowed the dissolution rate of starch. This study shows chitosan coating could enhance the water barrier and heat-resistant properties of STM.