New polyamides with long alkane segments: nylon 6.24 and 6.34

A series of new amphiphilic, semi-crystalline polyamides based on hexamethylenediamine and long alkane carboxylic diacids has been synthesized and characterized, here exemplified by polyamide 6.24 (PA-6.24) and polyamide 6.34 (PA-6.34). The polymers were produced by melt polycondensation, which yielded materials of weight-average molecular weights in the range of 30,000-35,000 g/mol. The thermal properties of the polyamides were investigated by various thermo-analytical methods. PA-6.23 and PA-6.34 exhibit relatively high melting temperatures of 189 and 177 degrees C, respectively. Both materials display rather poor solubility in solvents that are used for common polyamides, but by contrast, dissolve in, e.g. ethanesulfonic acid. PA-6.34 was found to aggregate in dilute methanesulfonic acid solutions and form thermo-reversible gels in H2SO4, which we attribute to its amphiphilic character. The latter enabled the use of PA-6.34 as a compatibilizer for blends of polyolefins and polyamides. Finally, the Young' a moduli of isotropic films of PA-6.24 and PA-6.34 were determined to be 1.3 and 0.7 GPa, respectively, representing a stiffness that is intermediate between that of common polyamides and polyethylene. (C) 2000 Elsevier Science Ltd. All rights reserved.