New polyamides with long alkane segments: nylon 6.24 and 6.34

A series of new amphiphilic, semi-crystalline polyamides based on hexamethy lenediamine and long alkane carboxylic diacids has been synthesized and cha racterized, here exemplified by polyamide 6.24 (PA-6.24) and polyamide 6.34 (PA-6.34). The polymers were produced by melt polycondensation, which yiel ded 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 v arious thermo-analytical methods. PA-6.23 and PA-6.34 exhibit relatively hi gh melting temperatures of 189 and 177 degrees C, respectively. Both materi als display rather poor solubility in solvents that are used for common pol yamides, but by contrast, dissolve in, e.g. ethanesulfonic acid. PA-6.34 wa s found to aggregate in dilute methanesulfonic acid solutions and form ther mo-reversible gels in H2SO4, which we attribute to its amphiphilic characte r. The latter enabled the use of PA-6.34 as a "compatibilizer" for blends o f polyolefins and polyamides. Finally, the Young' a moduli of isotropic fil ms of PA-6.24 and PA-6.34 were determined to be 1.3 and 0.7 GPa, respective ly, representing a stiffness that is intermediate between that of common po lyamides and polyethylene. (C) 2000 Elsevier Science Ltd. All rights reserv ed.