THERMAL-BEHAVIOR OF ALIPHATIC-AROMATIC POLY(ETHER-AMIDE)S

The thermal properties of a set of experimental aliphatic-aromatic pol yamides containing ether linkages were examined as a function of their chemical structure. Variations of the glass transition temperature (T -g) and melting temperature (T-m) could be correlated with the length of the aliphatic spacers and with the orientation of the phenylene rin gs. Polymers with a high concentration of p-oriented phenylene units s howed a higher T-g than those containing mainly m-oriented ones; T-g v alues ranged from 110 to 155 degrees C. Surprisingly, a negligible dep endence of T(g)s on the nature of flexible spacers was observed. For a ll of the polymers, the thermal stability was virtually the same, abou t 440 degrees C, when tested by dynamic thermogravimetric analysis (TG A). However, quite different levels of thermal stability were found by isothermal TGA analysis for polyamides with different flexible spacer s. Moreover, the poly(ether-amide)s described here compare fairly well with wholly aromatic polyamides when measured by dynamic TGA; but iso thermal TGA measurements clearly demonstrated that they decompose fast er than aromatic polyamides. Treatment of the TGA curves by the method of McCallum provided kinetic data that confirmed a better long-term s tability for poly(ether-amide)s with a higher proportion of para-orien ted phenylene rings. (C) 1998 John Wiley & Sons.