CHEMICAL MODIFICATION OF STARCH VIA ETHERIFICATION WITH METHYL-METHACRYLATE

Reaction of starch with methyl methacrylate (MMA) via etherification w as investigated under different conditions. Factors studied include so dium hydroxide concentration, methyl methacrylate concentration, react ion time and temperature, as well as the reaction medium. Results obta ined indicate that the extent of etherification increases as the amoun t of sodium hydroxide increases, attains a maximum then decreases. Pro longing the reaction time up to 20 h is accompanied by enhancement in the extent of etherification. Longer reaction time has no effect on th e extent of etherification since a stage of leveling off of the reacti on is attained. 55 degrees C constitutes the optimal temperature for t he etherification reaction. Higher or lower than 55 degrees C causes a decrease in the percent of etherification and degree of substitution. Neither aqueous nor nonaqueous medium presents suitable media for car rying out the MMA/starch etherification reaction. The reaction takes p lace easily when water/solvent medium at ratio 4 ml/4 ml was used. Hig her ratios prevents etherification by virtue of their very favourable effect on the swelling of starch.