Crystal Transition of Nylon-12,12 under Drawing and Annealing
Abstract
Summary: Wide-angle X-ray diffraction (WAXD) was used to investigate the crystal transition of nylon-12,12 under annealing and drawing. The triclinic α-form could be obtained by crystallizing from a melted state or by annealing the γ-form at high temperature (above 150 °C). The crystal structure of the α-form annealed at 90 °C didn't change with time except for the perfection of crystals and an increase in the degree of crystallinity. The pseudo-hexagonal γ-form could be produced by crystallizing from the melted state at low temperature (90 °C) or by drawing at 90 and 160 °C. This is the first time a Brill transition has been observed under drawing conditions, instead of under the traditional conditions of continuous heating and cooling. Experimental results also confirm that drawing inducement is preferable to produce the γ-form and plays an important role in determining the crystal structure; there is a competition between drawing inducement and thermal inducement.
