Preparation of Starch Carbamates in Homogeneous Phase using Different Mixing Conditions

The preparation of starch carbamates of wrinkled pea starch in homogeneous phase catalysed by dibutyltin dilaurate in DMSO as solvent is described. The empfloyed isocyanates have linear alkyl chains with 7, 9, 11, 15 or 18 carbon atoms. Starch carbamates with equal degrees of substitution and different alkyl chains lengths were synthesised in a reaction flask. The preparation of carbamates with equal alkyl chain length and different degrees of substitution was also possible. The structures of the polymers were characterised by elemental analysis, IR- and 1 H-NMR-spectroscopy. The behaviour of the prepared starch carbamates under thermal loading was investigated by using Differential Scanning Calorimetry (DSC) and a hot press. In addition, for 1-undecyl isocyanate the starch carbamate was prepared both in a kneader and an extruder. The differences in reaction conditions and the results were discussed.