MOLECULAR MOTION AND TRANSITIONS IN VARIOUS TYPES OF POLYAMIDES STUDIED BY THE FLUORESCENCE METHOD

Abstract

Microbrownian motion in polyamide chains is studied by the fluorescence method. In the first place, the validity of the estimation of molecular motion is studied. The relaxation properties of fluorescent polyamide (diamino stilbene-conjugate or DAS-conjugate in contraction) are compared with those of the usual nylon-6 in which free fluorescent dye (auramine-O or diacetylamino stilbene) is dispersed. In the dilute solution they give different relaxation times and the apparent activation energies. However, in the concentrated solution and especially in solids, either sample gives almost the same relaxation time and apparent activation energy.
Then, in the next place, the molecular motion and the transition in various types of bulk polyamide are studied using auramine-O as a probe. Transition temperature varies almost linearly with CED of the material, and the extrapolation to polymethylene gives the limiting value much higher than the glass transition temperature of polyethylene. Apparent activation energy also depends on CED.
Other properties such as dynamic modulus and X-ray parameters are compared with the fluorescence parameter. The effects of water on the relaxtion properties is also studied.
The mechanism of the transition is discussed on the basis of these experimental studies.