A Study on Local Segmental Motions of Methylene Chain in Poly(Butylene Terephthalate) in Solution Phase

摘要

Temperature dependent data of 13C spin-lattice relaxation times and NOE factors for methylene carbons at 50.3MHz and 125.5 MHz have been used to probe the local chain dynamics of poly(butylene terephthalate) (PBT) in solution phase. The interpretation of the relaxation data for methylene chain carbons in PBT was attempted on the basis of several proposed motional models, among which the DLM model was found to be superior. Analysis based on the DLM model indicated that the motion of the OCHgroups was more restricted compared with the central methylene carbon, which is consistent with conclusions from solid state experiments reported by other investigators. Librational amplitudes of terminal and central carbon of PBT were estimated to be 29.84∑ and 32.01∑,respectively.