Polymorphism and orientation development in melt spinning, drawing, and annealing of nylon‐6 filaments

Abstract

SynopsisA new method has been developed for determining the total crystallinity and relative amounts of a-and y-phases in nylon-6 samples. The procedure is based on a combination of X-ray and density data and does not require complicated analytical procedures to separate overlapping reflections. The technique has been applied to study the structural changes accompanying the melt spinning, annealing, and drawing of nylon-6 fdaments. Higher spin draw ratios result in higher crystallinity, greater relative amounts of y-phase, and higher orientation. Annealing up to 2 h in boiling water or a 20% aqueous formic acid solution decreases the y-phase content, increases the a-phase content and total crystallinity, but does not e l i t e all of the y-phase in samples spun with high spin draw ratios. Annealing in vacuum also i nthe a-phase content when annealing ia carried out at temperatures above 120°C, but there is little effect below thia temperature. Drawing of ae-spun and conditioned f b e n t a at 9o°C also increases the a-phase content and decreases the y-phase content. The total crystalline content increases with draw ratio for samples with low spin draw ratia, but drawing has littie effect on the total crystalline content of samples spun with higher spin draw ratios. Drawing also resulta in substantial increases in orientation, especially for samples spun with low spin draw ratioa The effecta of these changes in structure on the mechanical properties are.also dmribed.

Hydrogen bonding, mobility, and structural transitions in aliphatic polyamides

“…However, the two major families are a and c, and the others can be regarded as variants of these. 12 The chains in the a crystals are in the fully extended zigzag conformation, and the amide groups in the c crystals are rotated about 608 from that in a fully extended planar conformation, resulting in a shorter chain-axis repeat and the formation of pleated sheets. The hydrogen bonds are between antiparallel chains in a crystals and between parallel chains in c crystals [ Fig.…”

“…The transformation from c to a can be brought about by heat, strain, or solvents (water) either alone or in combination. 12,18,20,[25][26][27][28] The c form obtained by melt casting, spinning, drawing, and in some instance with nanoclays transforms into a before melting and is most likely a solid-state reorganization. However, the c form obtained by nucleation with nanoclays or by iodine treatments remains c up to melting.…”

Microstructural investigation of high-speed melt-spun nylon 6 fibers produced with variable spinning speeds

“…Also, they characterized the transitions that occurred between the crystal structures and examined the importance of crystal structures other than the well-characterized ␣ and ␥ forms. 3 Heuvel and Huisman 4 investigated the effects of winding speed on the crystalline structure of nylon 6 yarns at speeds varying from 700 to 5500 m/min, and Gianchandani et al 5 developed a new method for determining the total crystallinity and relative amounts of ␣ and ␥ phases in nylon 6 samples. Salem et al 6 characterized the ordered phases of spin-oriented nylon 6 fibers wound at speeds ranging from 5000 to 8000 m/min with wide-angle X-ray scattering (WAXS).…”

Study of the structure development during the melt spinning of nylon 6 fiber by on-line wide-angle synchrotron X-ray scattering techniques

“…Conditioned data from Bankar et al 12 and Gianchandani et al 32 are also plotted for comparative purposes. Deviations from the present work to that of the two listed above can be attributed to different temperature profiles in the extruder and sample molecular weight.…”