High-speed Melt Spinning Research Articles

Fiber Structure Development of PHBH through Stress-Induced Crystallization in High-Speed Melt Spinning Process

Fiber Structure Development of PHBH through Stress-Induced Crystallization in High-Speed Melt Spinning Process

Multiple Melting Behavior of High-Speed Melt Spun Polylactide Fibers

ABSTRACTHigh-speed melt spinning of polylactide (PLA) was conducted and the structure and multiple melting behavior of the as-spun fibers were investigated. In the analysis of temperature modulated differential scanning calorimetry (TMDSC) thermograms for the as-spun PLA fibers taken-up at 1 and 6 km/min, the peaks around the melting temperature region in the reversing heat flow (RHF) and nonreversing heat flow (NRHF) curves were mainly separated into (1) a pair of an endothermic peak (Peak L) in RHF and an exothermic peak (Peak R) in NRHF in a low temperature region, (2) an endothermic peak (Peak M) both in RHF and NRHF (only in RHF for PLA fiber spun at the low-speed) in an intermediate temperature region, and (3) an endothermic peak (Peak H) both in RHF and NRHF in a higher temperature region. Wide-angle X-ray diffraction (WAXD) measurements were conducted during the heating process of the as-spun fibers cut into powders. In the case of fibers obtained at 1 km/min, disordered crystals, i.e. α′-form crystals, were formed through cold crystallization followed by a disorder-to-order phase transition, i.e. α′ to α crystalline modification, with partial melting of the α′ crystals around 148.5°C in the temperature range of Peaks R and L. Finally, the α form crystals melted above 169.4°C, in the temperature range of Peak H. On the other hand, the PLA crystals generated by the orientation-induced crystallization during the spinning process at a spinning velocity of 6 km/min did not show a WAXD profile of perfect α form crystals but showed an intermediate structure having lattice spacings between the α′ and α forms. Such intermediate crystals did not transformed into α form crystals during the heating process.

Study on the Characterization and Evaluation Methods of PA6 Chips for High-Speed Spinning

Abstract The reasons for the significant difference of PA6 spinnability are discussed. For this research project, BASF PA6 chips (BASF, Germany) and PA6 chips (GC, China) were chosen as research objects. We chose these two different chips because BASF PA6 chips are stable and GC PA6 chips are unstable in high-speed spinning. The measurement of relative viscosity, crystallization rate, content of extractable matter, molecular weight and its distribution, and Fourier transform infrared (FTIR) spectroscopy of extractable matter were systematically investigated. Moreover, the screw extrusion process of PA6 melt in high-speed melt spinning was simulated by a capillary rheometer, in which PA6 samples with different melting times were prepared to conduct the above-mentioned tests. Compared to BASF chips, the GC chips have the higher content of extractable matter, the greater and more variable relative viscosity, the greater molecular weight, and the wider distribution, causing the poorer spinnability in high-speed spinning. Furthermore, the extractable matter in GC chips is the same as that in BASF chips, which is confirmed by FTIR spectra.

電子密度をマッチングさせた浸漬液中での小角X線散乱測定による高速紡糸ポリエチレンテレフタレート繊維の高次構造解析

X-ray total reflection by the surface of fibers produces strong streaks in the direction perpendicular to the fiber axis. In order to analyze higher-order crystalline structures in the fiber, the streaks overwhelm valuable scattering from the structures we intend to analyze. Shish-kebab structure is one of the most important higher-order crystalline structures because it plays a key role for imparting high strength to general fibers. It is known that the streaks due to the X-ray total reflection from the fiber surface can be eliminated by immersing fibers into a liquid of which electron density was matched to that of the PET fibers because the contrast between two neighboring objects is proportional to the square of the electron density difference between the two objects. For the sake of the precise structural analyses, we have conducted two-dimensional small-angle X-ray scattering (2d-SAXS) measurements at room temperature for poly(ethylene terephthalate) (PET) fibers prepared with high-speed melt spinning being immersed in non-solvent of which electron density was matched to that of the PET fibers. For this purpose, a bundle of the fibers was set in a quartz capillary of which axis is parallel to the fibers (the edge-view image). As a consequent, it was found that the spacing between the neighboring shish structures and that between the neighboring kebab structures were both increased with an increase in the spinning velocity. We also present a succeeded example of a sophisticated method for end-view 2d-SAXS measurements for the PET fibers dipped in the electron-density matching non-solvent, where the incident X-ray beam was exposed to the fibers from the direction parallel to the fiber axis. The result of this measurement was consistent with that of the measurements for the fibers in the quartz capillary.

Olive hue visible–near infrared camouflage properties of high speed melt spun poly(ethylene terephthalate) multifilament yarn

High speed melt spinning process was used to produce near infrared (NIR) camouflage poly(ethylene terephthalate) (PET) partially oriented yarns (POY) against natural olive hue by using C.I. Pigment Green 7 (0.1% weight fraction), C.I. Pigment Yellow 184 (0.05% weight fraction) and carbon black (CB) (0.01% weight fraction). The effect of drawing, texturizing and knitting processes on the reflectance properties of produced sample was evaluated, and it was concluded that knitted fabric by texturized yarns provides optimum simulation with natural olive hue. Also the effect of pigments and the process on the yarns' structure by using the thermal and mechanical tests of yarns was investigated. It was observed that the thermal and mechanical properties of all samples are in an acceptable range.

Mechanical response of melt-spun amorphous filaments

High-speed melt spinning of a cyclo-olefin polymer (COP) and a copolyamide (CoPA) have been performed. Differential scanning calorimetry curves of the resulting monofilaments show that they remain in an amorphous state even after hot drawing. Wide angle x-ray diffraction patterns of undrawn and drawn COP filaments show that although the material remains in an amorphous state, a degree of orientation is induced in the polymer after drawing. The amorphous filaments show an enhanced bending recovery with respect to different semi-crystalline monofilaments commercially available. However, single fiber axial compressive testing indicates that the amorphous filaments exhibit a compressive modulus value which is 50% lower than what is observed for a reference semi-crystalline PET filament. Analysis of the compressive strains applied by the bending recovery test indicates that while the maximum applied strains remain well within the region of elastic deformation of the amorphous materials, the threshold between elastic and plastic deformation is reached for the semi-crystalline materials.

Orientation of Well-Dispersed Multiwalled Carbon Nanotubes in Melt-Spun Polymer Fibers and Its Impact on the Formation of the Semicrystalline Polymer Structure: A Combined Wide-Angle X-ray Scattering and Electron Tomography Study

The orientation behavior of well-dispersed multiwalled carbon nanotubes (CNTs) within high-speed melt-spun semicrystalline polymer fibers has for the first time been studied using three-dimensional reconstructions from bright-field transmission electron microscopy (TEM) tomography. The local investigation technique allows separating contributions stemming from additionally present CNT aggregates. Over a relatively narrow draw ratio range applied during the fiber production process, a transition region is found, in which the CNTs change their orientation from being aligned perpendicular to being aligned parallel to the fiber axis. Complementary performed wide-angle X-ray scattering measurements and mechanical analysis of the polymer/CNT nanocomposite fibers reveal a strong correlation between the CNT orientation and the structural and mechanical properties of the fibers. Characteristic quantities such as crystallinity, crystal size, and correlation length parameters of crystalline and amorphous polymer cha...

PET高速溶融紡糸過程のオンライン広角X線散乱測定

We report results of on-line wide-angle X-ray scattering (WAXS) measurements for melt spinning process of poly(ethylene terephthalate) (PET). In order to obtain good results, we have conducted experiments by paying attention as much as possible. First of all, a special experimental set-up has been developed by employing a purge box which contains the spin line and the X-ray detector (imaging plate), as well, with helium gas purge, in order to minimize noise level due to air scattering. Furthermore, a high-molecular weight PET sample prepared by solid-state polymerization was used in order to increase the spin line stress, which accommodates us with starting of orientation-induced crystallization at low take-up velocities. A special care to minimize the swaying of the spin line has been taken as well by employing a perforated metal guard inside the spinning tube which covers the spin line from the spinneret to the winder with insertion of the helium gas purge box in the middle. This worked well for suppression of the air turbulence. By such special experimental treatments, we have succeeded in conducting on-line two-dimensional WAXS measurements during the high speed melt spinning of PET fibers with the take-up velocity of 1600m/min. As a high brilliant X-ray source, we utilized SPring-8 (Japan Synchrotron Radiation Research Institute, Harima, Japan). The combination of above mentioned techniques enabled us to obtain crystalline reflections from oriented crystals with only 2min exposure. Nevertheless, we observed no appreciable change in crystallinity and orientation of crystallites along the spin line. It is because the control of positioning the neck point where the crystallization sets in was sensitively influenced by the ambient gas condition. Further special care to overcome this difficulty should be taken in our future study.

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

In the last few years research activities have been focused on the modification of fiber properties with nano-scaled additives. One of the most important fields of research is the alteration of mechanical properties such as the tenacity and the specific breaking load. In this study, we determined the influence of nano-phyllosilicates on the drawability of polyamide 6 multifilament yarns. It was first demonstrated that the drawability of the fibers drastically increased in an industrially relevant high-speed melt spinning process. Structural properties of the material are identified by wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). Changes in the crystalline properties as well as in the alignment of the silicates are compared with the stress–strain curves of the fibers, and a molecular mechanism for the drawing process is derived from these experiments. In a first step, a significant phase transition in the crystalline structure unaffected by the silicates occurs for low draw ratios (DRs). Beyond this point, where unmodified fibers start to break, a gliding between the silicate layers takes place, which is responsible for an extended drawability of the fibers. This mechanism leads to new possibilities for fiber processing, which can be used to research ultra-fine filaments in future studies.

Studies on High-Speed Melt-Spinning of Polypropylenes with Highly Controlled Stereo Regularities

Studies on High-Speed Melt-Spinning of Polypropylenes with Highly Controlled Stereo Regularities

Effect of the Blending of Low Stereo-regularity Component in High-Speed Melt Spinning of Polypropylene

Effect of the Blending of Low Stereo-regularity Component in High-Speed Melt Spinning of Polypropylene

Effect of surface treatment and wetting behavior on fiber surface and resulted yarn property

A series of spin finishes with various wetting properties was prepared by incorporating different wetting agents into a formulated basic spin finish master batch. They are then applied to poly(ethylene terephthalate) (PET) high-speed melt spinning yarns. The wetting behavior of the fiber surface was evaluated by measuring the on-line spin finish distribution at various distances from the spin finish applicator. The on-line spin finish distribution became more uniform as the distance was increased to 120 cm, indicating that the spin finish continues to spread rapidly on the yarn surface at smaller distances. The variation in mass per unit length along the yarn (yarn evenness) was compared with the corresponding dynamic surface tension of the spin finish emulsion and with the on-line spin finish distribution on the yarn. The yarn evenness was decreased, with a poor on-line spin finish distribution, and with an increased difference between the dynamic surface tensions, Δ γ d, for bubbling rates of 1 Hz ( γ 1 Hz ) and 6 Hz ( γ 6 Hz ). The on-line spin finish distribution increases with Δ γ d to a Δ γ d value of 1.7 dyn/cm. Thereafter, further increasing Δ γ d causes spin finish splashing from the yarn, reducing the extraction weight of the spin finish from the PET yarn. However, yarn evenness initially decreases as Δ γ d increases, but levels off when Δ γ d exceeds 1.7 dyn/cm. Comparing with the surface friction and the surface dielectric property, we conclude that the wetting behavior of the fiber surface played a dominant effect on the PET high-speed melt spinning and, therefore, for the yarn evenness properties produced.

Melt Spinning of Poly(3‐hydroxybutyrate) Fibers for Tissue Engineering Using α‐Cyclodextrin/Polymer Inclusion Complexes as the Nucleation Agent

This paper reports on an attempt to use CD and CD/PHB ICs as nucleation agents for PHB in a high-speed melt spinning process. At first rheological and thermal properties of the nucleated melts are determined in order to assess the influence of the nucleating agents. Then spinning tests are carried out. Thermal and textile properties of the spun PHB fibers are also determined. An estimation of the improvement of inhibition of the secondary crystallization from use of the described blood compatible nucleating agents is given.

Structure and properties of syndiotactic polystyrene fibers prepared in high-speed melt spinning process

High-speed melt spinning of syndiotactic polystyrene was carried out using high and low molecular weight polymers, HMs-PS and LMs-PS, at the throughput rates of 3 and 6 g/min. The effect of take-up velocity on the structure and properties of as-spun fibers was investigated. Wide angle X-ray diffraction (WAXD) patterns of the as-spun fibers revealed that the orientation-induced crystallization started to occur at the take-up velocities of 2–3 km/min. The crystal modification wasα-form. Birefringence of as-spun fibers showed negative value, and the absolute value of birefringence increased with an increase in the take-up velocity. The cold crystallization temperature analyzed through the differential scanning calorimetry (DSC) decreased with an increase in the take-up velocity in the low speed region, whereas as the melting temperature increased after the on-set of orientation-induced crystallization. It was found that the fiber structure development proceeded from lower take-up velocities when the spinning conditions of higher molecular weight and lower throughput rate were adopted. The highest tensile modulus of 6.5 GPa was obtained for the fibers prepared at the spinning conditions of LMs-PS, 6 g/min and 5 km/min, whereas the highest tensile strength of 160 MPa was obtained for the HMs-PS fibers at the take-up velocity of 2 km/min. Elongation at break of as-spun fibers showed an abrupt increase, which was regarded as the brittle-ductile transition, in the low speed region, and subsequently decreased with an increase in the take-up velocity. There was a universal relation between the thermal and mechanical properties of as-spun fibers and the birefringence of as-spun fibers when the fibers were still amorphous. The orientation-induced crystallization was found to start when the birefringence reached — 0.02. After the starting of the orientation-induced crystallization, thermal and mechanical properties of as-spun fibers with similar level of birefringence varied significantly depending on the processing conditions.

High-speed Melt Spinning of Polyethylene terephthalate with Periodic Oscillation of Take-up Velocity

Abstract To investigate the non-steady-state melt spinning behavior, take-up velocity was varied periodically in the high-speed melt spinning process of polyethylene terephthalate and the time-course changes of velocity and diameter of the spin-line were measured simultaneously. A numerical simulation program for the non-steady-state melt spinning process was also developed. In the range of relatively low take-up velocities, experimental results and results of numerical simulation of the non-steady-state melt spinning process showed a fair agreement, in that the amplitude for the variation of the reciprocal of the cross-sectional area and that for the variation of velocity of the spin-line had a linear relation. An increase in the frequency of velocity oscillation led to a less significant variation in the thickness of as-spun fibers. On the other hand, there was a phase shift between the oscillation of take-up velocity and that of the reciprocal of cross-sectional area of the spin-line at the point of take-up. When take-up velocity was increased, starting of the orientation-induced crystallization along with the occurrence of neck-like deformation caused some characteristic behaviors such as significant increases in the amplitudes of velocity and diameter fluctuations at a certain region in the spin-line. Such behaviors could be reproduced in the numerical calculation by incorporating the stress dependent change of solidification temperature. It was also revealed that the orientation-induced crystallization has the effect of stabilizing the spinning system.

Complex morphology of melt-spun nylon-6 fibres investigated by 1H double-quantum-filtered NMR spin-diffusion experiments.

The complex morphology of high-speed melt-spun nylon-6 fibres hydrated with D2O was investigated using 1H double-quantum-filtered spin-diffusion NMR experiments. The magnetisation exchange from selected crystalline domains along the fibrils and interfibrils was simulated with the help of a three-dimensional solution of a spin-diffusion equation approximated by a product of one-dimensional analytical NMR signals, which correspond to a lamellar morphology. This allows to measure the sizes of crystalline and less-mobile amorphous domains along the fibrils, as well as the diameter of the fibrils and interfibril distances. A series of nylon-6 fibres with extreme values of winding speed and draw ratio was investigated. The changes detected in the domain size along the fibrils and interfibrils show the same trend in the data obtained from wide-angle X-ray diffraction and small-angle X-ray scattering.

Synchrotron X-ray Scattering and Precise Structural Analyses of Poly(ethylene terephthalate) Fibers Prepared by High Speed Melt Spinning

Precise structural analyses of high speed melt spinning fibers provide useful information of appropriate nano-structures for imparting ultra-high strength to general fibers. For quantitative and precise analyses by X-ray scattering measurements, strong X-ray source is required. In this paper, we demonstrate significance of the synchrotron X-ray scattering and precise structural analyses of poly(ethylene terephthalate) fibers prepared by high speed melt spinning, with the take-up velocity ranging 1∼9 km/min. Systematic changes in the 2d-SAXS (two-dimensional small-angle X-ray scattering) patterns were clearly observed as a function of the take-up velocity. For 3 km/min, only streaks on the equator were distinct. For 4∼6 km/min, characteristic X-shaped cross-streaks appeared with the streaks on the equator. Then, at 7∼9 km/min, a pair of broad streaked peaks parallel to the equator appeared instead of the cross-streaks, while the equatorial streaks still coexist. We ascribed the X-shaped cross-streaks to a zig-zag fibril structure, and the equatorial streaks with the broad streaked peaks to a shish-kebab structure. Then, based on the 2d-SAXS results, change in the fiber structures with an increase of the take-up velocity is considered. For 4∼6 km/min, the zig-zag fibril is dominant. However, a trivial amount of shish seems to coexist. The shape of fibril changed from zig-zag to straight with an increase of the take-up velocity, while the shish-kebab fraction was considered to increase. It is noted here that the zig-zag fibril consists of somewhat different from an ordinary fibril, but rather thicker-and-looser agglomerates of crystallites. At 9 km/min, fibril is no more the zig-zag, but a straight shish, with a well-developed kebab structure.

高速溶融紡糸過程における糸の横揺れ(流体工学II)

高速溶融紡糸過程における糸の横揺れ(流体工学II)

Fine structure formation and physical properties of poly(butylene terephthalate) fibres in high-speed melt spinning

Abstract Poly(butylene terephthalate) (PBT) fibres were obtained by high-speed melt spinning up to a take-up velocity of 8 km/min. Fine structure formation and physical properties of these fibres were investigated. The increase of take-up velocity caused raises in both density and birefringence. In wide-angle X-ray diffraction equatorial profiles, the increase of take-up velocity can be observed in the (010) and (100) reflections of β-crystals; the reflection peaks are the sharpest at a take-up velocity of 6 km/min. The initial modulus of the fibres arises when the fraction of β-crystals is increased, while the tenacity depends more on the fraction of α-crystals, i.e., the total crystallinity. Thermal properties of high-speed spun PBT fibres were measured with differential scanning calorimetry, dynamic mechanical and thermo-mechanical analysis, etc. Endothermic curves become sharper with increasing take-up velocity, and endothermic melting peaks are shifted to higher temperature. Crystal structures are well developed in fibres obtained at higher take-up velocities. The tan δ peaks of PBT fibres tend to shift to higher temperature and the peak intensity is decreased with increasing take-up velocity, i.e., the packing density of PBT fibres is high when the take-up velocity and thus the orientation of amorphous regions is increased. The shrinkage has a tendency to decrease with increasing take-up velocity.

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

The NMR spin-diffusion process taking place in a morphology represented by three different domains with arbitrary sizes and diffusivities is investigated. General analytical solutions valid for the full range of spin-diffusion times were obtained for a one-dimensional lamellar morphology. The accuracy of these solutions has been tested by predicting the domain sizes for a poly(styrene-b-methyphenylsiloxane) diblock copolymer and semicrystalline poly(ethylene oxide) and comparing them with previously reported data. The effects of large changes in the size of the interface domain and the spin-diffusion coefficients of this domain on the spin-diffusion decay and build-up curves can be analyzed by numerical simulations. General analytical solutions of the spin-diffusion equations were used for investigating the complex morphology of high-speed melt-spun nylon 6 fibers. The NMR mobile amorphous, NMR less-mobile amorphous, and crystalline phases of nylon 6 fibers hydrated with D2O were detected and quantified u...