Intermolecular and intramolecular contributions to the relaxation process in sorbitol and maltitol

Molecular mobility in sorbitol and maltitol is studied with spectroscopic t echniques and molecular dynamics simulations in order to evaluate the relat ive contributions of the intermolecular and intramolecular interactions inv olved in the relaxation processes. The results of the molecular dynamics si mulations performed on the polyols in the bulk or in vacuum compares well w ith the results of the analysis of the relaxation diagrams in the framework of the Perez et al. model. They both imply that the difference in the rela tive contributions of the intermolecular and intramolecular interactions as sociated with the different chemical architectures of the two polyols must be taken into account. The intermolecular interactions cannot be neglected and they are stronger in sorbitol than in maltitol in relation with the lin ear structure of this polyol. The intramolecular barrier, higher in the mal titol molecule with a more complex structure, could be at the origin of the higher junction temperature between the alpha and beta relaxation processe s.