Structural formation during melt spinning process

Katayama, Ken‐ichi; Nakamura, Katsuyuki; Amano, Toshihiko

doi:10.1007/bf02086256

Cited by 198 publications

(96 citation statements)

References 14 publications

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“…There are, however, a number of observations which are typical for the lower polymer concentrations considered here. Scanning electron microscopy-gives valuable information about the structure of the fibre but it should be realized that in the case of skin/core structures [23,24], the structure observed with this surface-sensitive technique is not representative for the whole fibre. Moreover, fibres often contain many different surface structures.…”

Section: Resultsmentioning

confidence: 99%

Gel-spun polyethylene fibres

et al. 1988

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In addition to spinning temperature, spinline stretching and spinning speed, the properties of gel-spun polyethylene fibres hot-drawn to the maximum draw ratio also depend on the polymer concentration, molecular weight and molecular weight distribution. Reducing the polymer concentration reduces the number of entanglements, and fibres with better properties are obtained. However, a minimum number of entanglements is necessary to ensure sufficient coherence of the entanglement network and avoid premature breakage of the spinline. Therefore, an optimal concentration exists which is shown to shift to a lower value for polyethylene with a smaller molecular weight distribution. Fibres with a tensile strength exceeding 6 GPa and a modulus of about 160GPa can be prepared as long as spinline stretching is avoided. A smaller molecular weight distribution enhances the deteriorating effect of spinline stretching. The difference in morphologies for as-spun fibres prepared from different gel compositions and under different spinning conditions also strongly affects the cold-drawing behaviour of the extracted as-spun fibres.

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Section: Resultsmentioning

confidence: 99%

Gel-spun polyethylene fibres

et al. 1988

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“…Online characterization of these processes using in-laboratory X-rays has been demonstrated (Chappel, Culpin, Gosden & Tranter, 1964;Katayama, Amano & Nakamura, 1968;Spruiell & White, 1975;Haberkorn, Hahn, Breuer, Dorrer & Matthies, 1993), although low intensity seriously limits the applicability. For example, a very long exposure time is needed for good signal resolution [2-4 h for wideangle X-ray diffraction (WAXD), 12-24 h for smallangle X-ray scattering (SAXS)].…”

Section: Introductionmentioning

confidence: 99%

Studies of Structure and Morphology Development During the Heat-Draw Process of Nylon 66 Fiber by Synchrotron X-ray Diffraction and Scattering Techniques

Hsiao¹,

Kennedy²,

Leach³

et al. 1997

J Appl Cryst

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Online studies of structure and morphology development during continuous drawing of a nylon 66 fiber at different temperatures were carried out using synchrotron wideangle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) techniques. From the two-dimensional (2D) WAXD measurement, unit-cell parameters were determined. The results confirm that the triclinic cell structure persists above the Brill transition temperature (about 443 K). With increasing temperature, the unit-cell dimension a (dominated by hydrogen bonding) remains almost unchanged, while b increases and c decreases (both show a step-change at 403 K, prior to the Brill transition). The constant value of a agrees with the argument that the hydrogen bonding is relatively immobile at high temperatures prior to melting. The step-changes in b and c suggest that a premelting process of small (or defective) crystals precedes the Brill transition. As a result, the anisotropic thermal expansion of the surviving larger crystals results in a step-change behavior. This hypothesis is consistent with the crystal density data as well as the morphology evaluation by SAXS. Several dimensions were extracted from the 2D SAXS data: lamellar crystal and amorphous thicknesses (along the fiber) determined by the correlation function method, and crystal fibril width (perpendicular to the fiber) determined by the Porod analysis. These results also indicate that drawing annihilates small crystals, but the strain effect is much less than the temperature effect.

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“…Several studies have been conducted for the on-line characterization of structure development for synthetic fibers during drawing using simultaneous synchrotron radiation as well as laboratory X-ray generators for WAXD and SAXS [10][11][12]. Schultz et al [8,9] reported that unit cell dimensions, crystallinity, and orientation were dependent on stretching temperature and strain.…”

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confidence: 99%

Initial structure development in the CO2 laser-heated drawing of poly(trimethylene terephthalate) fiber

Kim

Kang

Murata

et al. 2008

Polymer

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Because rapid and uniform laser heating can fix the neck-drawing point in continuous drawing of PTT fiber, we have successfully analyzed the fiber structure development in the continuous drawing process by in-situ measurement with a time resolution of less than 1 millisecond. In this study, we investigated fiber structure development for PTT around the neck point controlled with a CO 2 laser-heated apparatus during continuous drawing, through on-line measurements of WAXD, SAXS, and fiber temperature. Fiber temperature attained by laser radiation initiated a rise around -3 mm in relation to the neck point at 0 mm, and increased to about 90°C, which is past the 45°C T g for PTT. The instantaneous increase in fiber temperature continued with a vertical ascent, with plastic deformation around the neck point. The crystalline diffraction pattern was revealed initially at the elapsed time of 0.415 ms immediately after necking, and remained fairly constant with elapsed time. The ultimate crystalline diffraction pattern for a completely drawn fiber showed little difference from that at the initial stage. In PET a two-dimensionally ordered structure in the form of a mesophase was detected immediately after the necking, whereas in PTT the phenomenon was not observed. With elapsed time, the d-spacing of (002) plane decreased gradually due to transformation of the initial all-trans conformation into trans-gauche-gauche-trans conformation, and ultimately the PTT molecular chain could favorably adopt the trans-gauche-gauche-trans conformation. SAXS pattern immediately after the necking revealed an X-shape; the scattering intensity concentrated on meridian directions due to individual crystal development, and at 2 ms two-pointed scattering started to appear. Past 8 ms, the typical two-pointed scattering pattern was prominent and its intensity increased with elapsed time. Long period decreased with increasing elapsed time, but the crystallite size of meridian (002) plane hardly changed. The decrease in long period might be caused by chain relaxation in the amorphous region.

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Structural formation during melt spinning process

Cited by 198 publications

References 14 publications

Gel-spun polyethylene fibres

Gel-spun polyethylene fibres

Studies of Structure and Morphology Development During the Heat-Draw Process of Nylon 66 Fiber by Synchrotron X-ray Diffraction and Scattering Techniques

Initial structure development in the CO2 laser-heated drawing of poly(trimethylene terephthalate) fiber

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