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

General Analytical Description of Spin-Diffusion for a Three-Domain Morphology. Application to Melt-Spun Nylon 6 Fibers

“…The fact that only two components can be detected shows that the process of spin-diffusion between less-mobile amorphous and crystalline phases is much faster compared to the longitudinal relaxation. Therefore, in agreement with the reported data for T 1 ρ , the short values for T 1 are attributed to the mobile amorphous phase and the long values to the less-mobile amorphous and crystalline phases . This assignment is also supported by the relative contributions of the integral amplitudes of the relaxation components.…”

“…A contribution of 2.2%−13% is measured for the mobile amorphous phase. These values are in the same range as those reported before for the high-speed melt-spun nylon 6 fibers using T 1 ρ measurements . A very small amount of mobile amorphous phase was detected for nylon fiber 6 fiber spun at 5000 m/min, and the highest value is obtained for the fiber spun at 500 m/min and drawn at DR = 4.5, in agreement with the data obtained from the decomposition of 1 H spectra (compare Tables and ).…”

“…The results from the 1 H line shape decomposition show that the less-mobile amorphous and mobile amorphous phases transform into the crystalline phase during high-speed spinning of the nylon 6 fibers (compare the A values for samples spun at 500 m/min and at 5000 m/min in Table ). The same result was reported by Kwak et al for high-speed melt-spun nylon 6 fibers using various physical methods including solid-state 1 H NMR spectroscopy and relaxometry.…”

“…Therefore, in agreement with the reported data for T 1F , the short values for T 1 are attributed to the mobile amorphous phase and the long values to the less-mobile amorphous and crystalline phases. 28 This assignment is also supported by the relative contributions of the integral amplitudes of the relaxation components. A contribution of 2.2%-13% is measured for the mobile amorphous phase.…”

“…The segmental dynamics of nylon 66 were investigated by deuterium NMR spin−lattice relaxation and line-shape simulations. They revealed the existence of “free” and “constrained” amorphous populations. , This result is confirmed by studies by X-ray diffraction which indicate that there are three different phases in nylon 6 fibers: crystalline, unorientated amorphous located in the lamellar stack, and orientated amorphous located between the fibrils. , Furthermore, the existence of a mobile amorphous phase aditionally to the crystalline and rigid amorphous phases in nylon 6 fibers has been proved by measurements of the 1 H spin−lattice relaxation in the rotating frame ( T 1 ρ ), and a processing-microstructure and chain motion relationship was established. , The fraction of each phase was estimated from the T 1 ρ magnetization decay. It was shown that it is dependent on the processing spinning speed.…”