Changes in superstructure and mechanical properties of poly(ethylene‐2,6‐naphthalate) fibers with critical necking tension

Abstract

Poly(ethylene-2,6-naphthalate) fibers were zone-drawn under a critical necking tension ( c ) defined as the minimum tension needed to generate a necking at a given drawing temperature (T d ). In the zone drawing under c , the neck was observed from 110 to 160°C. The superstructure in a neck zone induced at each T d was studied. The c value decreased exponentially with increasing T d and dropped to a low level at a higher T d . The draw ratio increased rapidly with T d increasing above 90°C, but the birefringence and degree of crystallinity decreased gradually. To study the molecular orientation in the neck zone, we measured a dichroic ratio (A P /A Ќ ) of a COO band at 1256 cm Ϫ1 along a drawing direction in the neck zone with a Fourier transform infrared microscope. A P /A Ќ at T d ϭ 110°C increased rapidly in the narrow neck zone, and that at T d ϭ 140°C increased in the edge of the wide neck zone. Wide-angle X-ray diffraction patterns of the fibers obtained at T d ϭ 130°C and lower showed three reflections due to an ␣ form, but those at T d ϭ 140 and 150°C had reflections due to the ␣ form and a ␤ form.

Effects of Take-up Speed of Melt Spinning on the Structure and Mechanical Propertiesof Maximally Laser Drawn PA9-T Fibers

“…As for example, T g of highest DR max of TUV 200 fibre is around 153°C in compare to the lowest DR max of TUV 1000 fibre around 148°C. The viscoelastic curves of a polymer give valuable information about its physi- cal network formed by crystallites and molecular entanglement [42]. Thus the DR max of TUS 200 sample evidently has the maximum crystallinity, which restricts molecular mobility in the amorphous regions.…”