Chemical modification of starch with hexamethylene diisocyanate derivatives

Chemical modification of potato starch in a two-step process has been presented. At the first stage the starch modifiers, i.e. isocyanate derivatives were synthesised by the equimolar reaction between hexamethylene diisocyanate (HMDI) and monoalcohol or monoamine. Proton NMR analysis has revealed that the prepared modifiers contain monoisocyanate compounds with respectively urethane or urea bonds, as the main products. Synthesis of HMDI-derived modifiers was followed using DSC method and the reaction products were characterized by the FTIR spectroscopy. At the second step starch was modified with the synthesised HMDI derivatives, in N-methylpyrrolidone slurry. Some properties of the obtained starch polymers were investigated and compared, i.e. efficiency of substitution, IR spectra, hydrophobic/hydrophilic features, DSC thermograms (melting temperatures) as well as moldability (hot press melt flow).