Solid State 13C\text{}^{13}C NMR Study of Modified Polyhydroxybutyrate

Structural changes in polyhydroxybutyrate (PHB) brought about by addition of chain extender and/or plasticizer were studied using $\text{}^{13}C$ MAS NMR spectra, which were measured using the direct polarization technique at 30 and 98°C. Four resonances associated with the CO, CH, $CH_{2}$ and $CH_{3}$ groups of PHB were observed in the spectra. The $CH_{3}$ resonance appearing at 98°C shows splitting into two lines related to the crystalline and amorphous regions. Analysis of the $CH_{3}$ resonances made it possible to estimate the influence of applied modifications on crystallinity and distribution of conformations in amorphous and crystalline domains of PHB samples