Thermal properties of poly(alkylene dicarboxylate)s derived from 1,12-dodecanedioic acid and even aliphatic diols

A series of new aliphatic polyesters derived from 1,12-dodecanedioic acid and different diols with an even number of methylene units have been studied to assess the effect of the chemical structure on the final thermal properties of the materials. The polyesters have high thermal stability and are fast crystallizing polymers, with crystallization rate similar to that of polyethylene (PE). This behavior is connected to the fact that long aliphatic chains assume conformational characteristics very similar to that of PE. However, the polyester prepared from ethanediol shows a peculiar behavior (for example, double melting peak, melting and crystallization temperatures, which do not fit the trend of those of the other samples and ringed spherulites) owing to a probable different conformation, deviating from the all-trans planar typical of PE. In the isothermal crystallization studies, a bell-shape trend has been found for the crystallization rate as a function of the number of -(CH2)- units in the diol. The high crystallization rate of the sample with long -(CH2)- sequences has been attributed to the high chain flexibility and, thus, high mobility in the molten state and ease of chain folding. By reducing the aliphatic sequence length, instead, implications of the structural characteristics of the samples are probably involved. (c) 2007 Wiley Periodicals, Inc.