Esterified modified corn starch has been prepared with corn starch as raw material,
acetic acid as activator, acetic anhydride as esterifying agent, and concentrated sulfuric
acid as catalyst. Certain substitution degree (DS=0~0.5) of starch acetate (SA) was prepared.
Esterified starches reaction conditions were optimized by single factor and orthogonal
experiment. Esterified starch was characterized using Fourier transforms infrared spectroscopy
(FTIR), scanning electron microscope (SEM) and differential scanning calorimetry
(DSC) analysis method. The experimental results show that under the conditions where temperature is 75oC,
time is 1.5h, concentrated sulfuric acid is 0.13mL, acetic acid is 0.7 (volume ratio of acetic acid and acetic
anhydride), substitution degree of SA can reach 0.45. The esterified starch FTIR analysis proves that acetyl
groups are introduced successfully. Starch microstructures of SEM show that the esterified starch has a loose
and porous structure. DSC analysis shows that the melting temperature of starch decreases with the increase
of substitution degree, which made film formation possible.