Thermomechanical, X‐ray and IR investigations of polyamide‐12 films

The thermomechanical curves of monoaxially drawn PA‐12 films are recorded. The films were previously subjected to annealing at different temperatures from 40°C to 170°C. The values of T g and T m derived from the thermomechanical curves show non‐linear dependence on the applied tension stress. The intensity of the IR absorption bands assigned to the folded conformation of the macromolecules increases with the rise of annealing temperature. In the IR spectrum of the film annealed at 170°C and subjected to additional drawing the intensity of these bands decreased as the degree of drawing increased. These results are interpreted as an indication for crystallization with folding of the macromolecules upon annealing and defolding under the conditions of recording of the thermomechanical curves. WAXS patterns suggest the presence of γ crystalline modification in PA‐12 under the conditions applied.