Abstract
In order to test the applicability of the phenomenological theory of linear viscoelasticity to semicrystalline polymers, creep measurements were performed on oriented nylon 66 filaments. Stresses used were 0.10, 0.35, and 0.50 g/den; the temperature range was 25° to 150° C; and the samples were maintained in an anhydrous atmosphere. Under these conditions, Boltzmann's superposition principle was found to apply. By employing time–temperature superposition and the stress relaxation data of Dunell, Joanes, and Rye [4], the creep compliance at 25° C over 26 decades of time can be obtained. Three dispersion regions are indicated; however, there is only a tenfold variation in compliance. The shift factors log a T, which give the temperature dependence of the master compliance curve, are linear in temperature from −100° to +150° C. These results on nylon 66 agree in general with the behavior of other semicrystalline polymers studied by Nagamatsu [8]. Although no molecular interpretation is given, the glass-to-rubber transition, common to amorphous polymers, is seen to be quite unlikely as a possible mechanism.
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