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In present work structural properties and aging of thermoplastic starches prepared by plasticization of cornstarch with urea, glycerol and their mixtures are studied using solid‐state 1H NMR and 13C NMR spectroscopy and WAXS measurements. Broad line 1H NMR spectra reveal phase separation of plasticizers during aging of the samples with the same or higher relative amount of glycerol than the amount of urea. Glycerol in the TPS samples induces motion of starch chain segments, the mobility of which depends on the relative amount of glycerol. At the scale of nm, formation of B‐type crystallites in the samples containing glycerol and also of single‐helical crystallinity in all samples is observed during one‐year aging through cross‐polarization magic angle spinning 13C NMR spectra. Urea, when used as the sole plasticizer, prevents the ordering of starch chains in B‐type crystallites. WAXS diffractograms show that regular crystals do not form in any of the samples.

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