Crystallization studies on linear aliphatic polyamides derived from naturally occurring carbohydrates



The thermal behavior of three series of sugar-derived polyamides (PA-nSu) made from the arabinaric, mannaric and galactaric acids, respectively, and α,ω-alkanediamines containing from 6 to 12 methylene units was investigated by DSC supported by polarizing optical microscopy. Crystallization from the melt under both isothermal and nonisothermal conditions was studied in detail. Melting temperatures of PA-nSu were found to decay steadily with the length of the polymethylene segment. Data registered from isothermally crystallized samples were analyzed by the kinetics Avrami approach, which revealed that crystallization initiated by combination of instantaneous and sporadically nucleation. Crystallization half-times indicated that “crystallizability” of PA-nSu increases with the number of methylenes in the diamine unit and decreases with the length of the carbohydrate-derived unit. Higher crystallinities were attained for polyamides made of shorter aldaric acids. The relation between thermal data and the configuration of the sugar moiety present in PA-nSu was discussed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010