Crystalline behaviors and phase transition during the manufacture of fine denier PA6 fibers

Abstract

Recently we have successfully produced fine denier PA6 fibers by using additives containing lanthanide compounds. Meanwhile, crystallization and phase transition of PA6 fibers during spinning and drawing processes were investigated. During the spinning process, β phase crystal could be obtained in as-spun PA6 fibers which were produced with relatively high melt draw ratio, while γ phase crystal predominated when the melt draw ratio was relatively low. β phase crystal, whose behaviors are similar with those of γ phase by FT-IR and XRD characterization, could be transformed to α form easily when PA6 fibers are immersed in boiling water. However, γ phase crystal of PA6 remains unchanged in boiling water. Thus, β and γ phase crystals of PA6 can be differentiated by the crystalline behaviors of PA6 fibers after treatment in boiling water. Further experiments demonstrate that the β phase can also be produced during a drawing process where a phase transformation from γ to α occurs. In other words, β phase may act as an intermediate state during the phase transformation.

Modification of the mechanical properties of polyamide 6 multifilaments in high-speed melt spinning with nano silicates

“…Therefore, annealing at 190 C is necessary. 13 Since polymer chains are more stretched in the g phase, these chains' formation is also preferred in strain-induced crystallization under mechanical stress with the result that this phase is preferred after the drawing processes. 8 The g phase is gradually transformed to the a phase during annealing at temperatures higher than 160 C. 3…”

Synthesis and Characterization of Unsaturated Biobased-Polyamides from Plant Oil

“…The hydrogen bonds in the γphase of polyamides are patterned between the parallel chains in a twisted conformation. 36,37 The 2θ ∼ 21°in the XRD pattern of PA 6 is also attributed mainly to the diffraction of the 001 plane, while in the Kevlar 49 fiber, 2θ ∼ 21°is assigned to the equatorial reflection of the 200 plane. 38−40 The reflection positioned at 2θ ∼ 24°is the predominant reflection for TH-PA (DMOD-PXDA), and one of the reflections for MH-PA (DMOD-PXDA) which is assigned to the α-phase (Figures S7 and S8).…”

Fracture Failure Mechanisms of Long Single PA6 Fibers

“…The material properties of PA6 fibers vary according to the manufacturing technique employed in their production, and a number of manufacturing techniques have been developed [ 14 , 15 , 16 ]. Zhang et al [ 14 ] successfully produced fine-denier PA6 fibers using additives containing lanthanide compounds, and the crystallization and phase transition of the resulting PA6 fibers were investigated during spinning and drawing processes. Polyvinylidene fluoride (PVDF) fiber mats with average fiber diameters of 200–2000 nm were fabricated under controlled electro-spinning conditions [ 16 ].…”