Influence of Starch and Glycerol on the Properties of Chitosan by Positron Annihilation Spectroscopy

摘要

Two types of chitosan (CS), alpha and beta, were blended with different concentrations of starch and cast to obtain films. The addition of 1% glycerol was used as a plasticizer to increase film flexibility. The properties of the obtained films were studied by positron annihilation lifetime spectroscopy, X-ray diffraction, and scanning electron microscopy. The results indicate that pure beta-CS had smaller size free-volume holes with high fractions than pure alpha-CS; this was attributed to the difference in bonding of main chains in beta-CS. The addition of starch (>20% up to 50%) reduced the size of the free-volume holes and increased their fraction because of the close packing of chain segments. The effect of 1% glycerol to the CS starch blends indicated that some modification took place.