Abstract:

The change of the chemical reaction property of ultrasound—treated cornstarch(UTCS)was investigated.By the reaction of UTCS with epoxy-propane,it is found that the degree of substitution(Ds)of UTCS increases from 0.1 13(the control sample)to more than 0.225,and that the Ds of UTCS increases a little with ultrasonic power.However,the increase in reaction time results in little improvement of the Ds.It is also found by polarized light micrograph that the crystal structure of UTCS granules shows no great change after the treatment by ultrasonic.Moreover,by using the scan electronic microcopy(SEM),many holes with diferent sizes are observed on the surface of UTCS granule,some of which take on the alveolate shape and distribute evenly in some starch articles.It is thus concluded that the ultrasonic contributes only in the amorphous region on the surface of the starch granule.

Key words: cornstarch, starch granule, epoxy-propane, ultrasonic, reaction property, structure