Graft polymerization of acrylic acid onto corn starch in aqueous isopropanol solution

The graft polymerization of acrylic acid (AA) onto corn starch well-swollen in aqueous isopropanol (IPA) was carried out by controlling reaction varia bles such as the concentrations of AA, initiator (a mixture of ammonium per sulfate and sodium metabisulfite) and IPA as well as the temperature and ti me of reaction for the acquirement of products with good efficiency. Homopo ly(acrylic acid) existing in the product mixture was removed by extraction with aqueous ethanol. In the temperature range of 30 degrees C to 60 degree s C the conversion gradually increased with increasing both reaction temper ature and reaction time. The graft reaction showed a tendency to give high conversions even at reaction temperatures above 40 degrees C. The reaction in aqueous IPA solution was more homogeneous and efficient than that in wat er. In addition, even though an equivalent quantity of initiator was used, the reaction conversion increased with increasing the concentration ratio o f AA to corn starch. It was also found that the average distance between gr afted sites decreased as the quantity of initiator and reaction temperature were increased.