13C spin-lattice relaxation times and nuclear Overhauser effect factors were measured as a function of temperature in two magnetic fields for poly(/&hydroxybutyrate) (PHB) in chloroform-d. The relaxation data were interpreted in terms of chain segmental motion and methyl internal rotation by using various dynamic models. Among these, the Dejean-LauprCtre-Monnerie model offered the best description of the segmental motion along the PHB chain. However, all models used in this study resulted in similar activation energy (17 kJ mol- ) for cooperative segmental motion. An activation energy of 1 l- 12 kJ mol- was found for methyl internal rotation. Further relaxation experiments on PHB in chloroform-d as a function of concentration and molecular weights were carried out as well
Посилання на статтю:
13C nuclear magnetic relaxation and dynamic behaviour of poly(P-hydroxybutyrate) in chloroform solution / Maria Elena Nedea and R. H. Marchessault* // Polymer. – 1992. – Vol 33. – P. 1831-1835.