Abstract: | The relaxation behaviour of the sodium salt of poly (L -glutamic acid) in the solid state has been examined by means of dynamic mechanical spectroscopy. Bound water was found to exert a profound influence on the relaxation behaviour and on a bulk property, the rigidity. Certain features of the loss spectrum have been identified with the hydration-dependent β-to-α conformational transition. Thus two side-chain relaxations are observed below ambient temperature, one associated with the β from (β1β) and a second at a lower temperature associated with the α form (β1α). The greater rigidity of the α form below the relaxation temperature and the larger rigidity drop accompanying the β1α can be explained in terms of the structural differences of the two conformations. |