Adjusting Experimental Parameters to Modify Corn Starch with Glycidyl Methacrylate to Tune Specific Properties

Chemical modification reactions are viable alternatives for improving the properties of starch because they allow the insertion of molecules that change the original behavior of the polymer. Glycidyl methacrylate (GMA) is an example of a vinylic molecule added to starch to decrease its hydrophilicity and improve mechanical properties. This modification reaction is affected by parameters like the volume of the modifier, time, and temperature. Furthermore, the correlation between these parameters might change the response of an individual parameter on the degree of substitution (DS), crystallinity (X_c), and molecular-weight-related parameters. This work evaluated how these effects and their correlations would affect DS, X_c, molecular weight, and polydispersity index (PDI) of starch. The results suggested that, while higher volumes of GMA and temperatures decreased the DS and X_c, the correlation between them increased the DS by 2.47, and X_c by 1.25. On the other hand, higher temperatures also favored the occurrence of hydrolysis. Also, although none of the parameter correlations had a significant effect on the assessed properties (at 95%), the statistical analysis confirmed that the correlation between two parameters changed the effect of individual parameters.

Keywords:
chemical modification; factorial design; natural polymer; polysaccharide; physical-chemical characterization