Secondary transitions of aryl-aliphatic polyamides IV. Dynamic mechanical analysis

Dynamic mechanical analysis was performed on the aryl-aliphatic copolyamide s, based on lactam-12 sequences, a tere- or iso-phthalic moiety, and a 3,3' -dimethyldicyclohexylmethane unit in regular order, whose dielectric relaxa tion, C-13 NMR and H-2 NMR investigations are reported in the preceding pap ers of this series. It demonstrates the existence of three secondary relaxa tions, gamma, beta and omega, which occur in the temperature and frequency ranges where similar secondary relaxations are observed by dielectric relax ation. Comparison of the results obtained in the present paper with those d erived from the whole set of experiments carried out on these materials lea ds to a precise description of the local motions that are responsible for t he observed secondary relaxations. (C) 2000 Elsevier Science Ltd. All right s reserved.