High-speed Melt Spinning Of Poly Research Articles

Melt-Spun Fibers from Bio-Based Polyester-Fiber Structure Development in High-Speed Melt Spinning of Poly(ethylene 2,5-furandicarboxylate) (PEF).

Poly(ethylene 2,5-furandicarboxylate) (PEF) is regarded as a bio-based alternative or complementary polyester for the widely used fossil resource-based polyester, poly(ethylene terephthalate) (PET). High-speed melt spinning of PEF of low and high molecular weight (L-PEF, H-PEF) was conducted, and the structure and properties of the resultant as-spun fibers were investigated. The occurrence of orientation-induced crystallization was confirmed for the H-PEF at the take-up velocity of 6.0 km/min, the highest speed for producing PET fibers in the industry. Molecular orientation and crystallinity of the as-spun fibers increased with the increase of take-up velocity, where the H-PEF fibers always showed a higher degree of structural development than the L-PEF fibers. The tensile modulus of the high-speed spun H-PEF fibers was relatively low at 5 GPa, whereas a sufficiently high tensile strength of approximately 500 MPa was measured. These values are adequately high for the application in the general semi-engineering fiber field.

Effect of Polycondensation Catalyst on Fiber Structure Development in High-Speed Melt Spinning of Poly (Ethylene Terephthalate).

We conducted a preliminary study on fiber structural development in the high-speed melt spinning of environmentally friendly polyethylene terephthalate (Ti-PET) synthesized with 25 ppm of titanium-based catalyst, which was compared with conventional PET (Sb-PET) synthesized with 260 ppm of antimony-based catalyst. Gel permeation chromatography of Ti- and Sb-PET resins of intrinsic viscosity 0.63 confirmed that both resins have similar molecular weights and distributions. However, differential scanning calorimetry revealed that the Ti-PET resin exhibited a lower melt–crystallization peak and isothermal melt-crystallization rate than the Sb-PET resin. High-speed melt spinning of the Ti- and Sb-PET was possible up to a spinning velocity of 6 km/min. Two-dimensional wide-angle X-ray diffraction analyses showed that the molecular orientation of the obtained as-spun Ti- and Sb-PET fibers increased with spinning velocity, and a highly oriented, crystalline structure by orientation-induced crystallization started to appear from 5 km/min. Notably, Ti-PET fibers showed a lower degree of crystalline structural development and lower tensile strength compared with Sb-PET fibers under the high-speed spinning conditions. Our results suggest that the catalyst in PET resins can act as nucleating agents in thermal- and orientation-induced crystallization, and that differences in catalyst content can influence PET fiber structure development under extreme conditions in high-speed melt spinning.

Necking behavior in high-speed melt spinning of poly(ethylene terephthalate)

The necking behavior in the high-speed melt-spinning process of poly(ethylene terephthalate) (PET) was analyzed using a mathematical simulation under a nonisothermal condition. A constitutive model into which the strain-rate dependence of viscosity and the strain-hardening effect are incorporated was used. Based on the simulated results, the cause of a local reduction of apparent viscosity was found to be due mainly to high strain rate. Also the onset of crystallization, if it occurred, was found to happen near the end of the neck. In addition, with no crystallization involved, the necking can still occur. The deformation process in high-speed spinning of PET was found to consist of two regions along the spin line: a Newtonian flow region and a rubberlike deformation region. The necking behavior is discussed here in terms of strain-rate sensitivity and strain-hardening parameter. As a result, a criterion for the onset of stable necking has been obtained. The necking behavior does not seem to be essentially different from that in cold drawing. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 446–456, 2000

Fiber Structure Development in High-Speed Melt Spinning of Polyethylene terephthalate-co-ethylene 2,6-naphthalene dicarboxylate)

High-speed melt spinning of Poly(ethylene terephthalate-co-ethylene 2,6-naphthalene dicarboxylate) P(ET/EN) with EN content of 8% was performed. The structure and mechanical properties of the as-spun fibers thus produced in the take-up velocity range of 0.5 to 7.5 km/min were characterized and compared with those of high-speed spun PET fibers. Molecular orientation increased with an increase in the take-up velocity. The development of molecular orientation of P(ET/EN) was more significant than that of PET at low take-up velocities. Accordingly, orientation-induced crystallization of P(ET/EN) started to occur at a slightly lower take-up velocity compared with PET. On the other hand, the maximum birefringence of P(ET/EN) attained at about 6 km/min was lower than that of PET. Although the crystallization temperature estimated from the thinning behavior of the spinning line is similar, density of P(ET/EN) as-spun fibers obtained at high-speed region was significantly lower than that of PET fibers indicating that the crystallization into PET crystals was suppressed by the addition of EN component to PET.

Effect of metallic wire inserted in nozzle in high-speed melt spinning of poly(ethylene terephthalate)

High-speed melt spinning of poly(ethylene terephthalate) was performed using a spinning nozzle with an inserted metallic wire of various lengths (0, 8, 30, and 45 mm). The molecular orientation of as-spun fibers increased with the increase in the wire length at all the take-up velocities examined. Along with the enhanced molecular orientation, the longer wire length led to the starting of orientation-induced crystallization at lower take-up velocities. The structure of crystallized fibers obtained at low speeds can be characterized by high crystallinity and relatively low molecular orientation. From the on-line measurement of the diameter and temperature profiles of the spin line with the 30-mm metallic wire, it was revealed that the spin-line had a maximum diameter of about 6 mm at the wire end. The spin-line temperature at this position was about 190°C. The solidification of the spin-line occurred at positions much closer to the spinneret in comparison with ordinary high-speed spinning. These results show that high-speed spinning with a wire inserted in the nozzle corresponds to a spinning process operated at extremely low extrusion temperature using a nozzle with an extremely large diameter. From the starting of orientation-induced crystallization at lower levels of birefringence in comparison with ordinary high-speed spinning, the alteration of the inherent fiber structure that cannot be represented by birefringence was also suggested. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 665–674, 1998

Effect of Liquid Isothermal Bath in High-Speed Melt Spinning of Poly(ethylene 2,6-naphthalene dicarboxylate).

The high-speed melt spinning process of poly (ethylene 2,6-naphthalene dicarboxylate) (PEN) was modified using a liquid isothermal bath (LIB) which was kept at a liquid temperature of 150 or 170°C. The structure and mechanical properties of the as-spun fibers thus produced in the take-up velocity range of 0.5 to 7.0 km/min were characterized. The fiber structure development in the low take-up velocity region was promoted by the use of the LIB and the promotion becomes more prominent by raising the liquid temperature. In case of the fibers produced with the LIB temperature of 170 °C, initial Young's modulus of about 25 GPa and tenacity of about 800 MPa, which are equivalent to the properties for the fibers prepared in the standard high-speed spinning process of 7 to 9 km/min, were obtained at 3 to 4 km/min. On the other hand, plots of the structural and mechanical parameters against the birefringence for the LIB fibers showed a similar relation in comparison with the fibers prepared in a standard high-speed spinning process indicating that the general mechanism of fiber structure development is similar in both the spinning processes. The LIB fibers obtained in the high-speed region were found to have a large amount of β modification crystals as in the case of the common high-speed spun fibers. The amount of β form crystals in the LIB fibers increased with an increase in the take-up velocity. From these results, it was concluded that the β form crystal can be formed even at a much lower temperature than the critical temperature for the formation of β form crystals in an isotropic state, and that the formation of β form crystals can be promoted by applying a higher tensile stress in the spin-line.

Fiber structure formation in ultra-high-speed melt spinning of poly(ethylene 2,6-naphthalene dicarboxylate)

The high-speed melt spinning of poly(ethylene 2,6-naphthalene dicarboxylate) (PEN) was performed up to the take-up velocity of the ultra-high-speed region, 9 km/min. From the investigations of the structure and physical properties of the as-spun fibers, the high-speed spinning of PEN was divided into three regions in terms of the mechanism of fiber structure formation. The first region is the take-up velocity of up to 2.5 km/min and the birefringence of up to 0.08 where only a slight increase in molecular orientation was attained. At the take-up velocity of 2.5–4.5 km/min and the birefringence of 0.08–0.25, although some experimental evidences indicated that the orientation-induced crystallization did not occur, there was an increase in the fiber density which suggested the formation of some ordered structure. At the take-up velocity > 4.5 km/min and birefringence > 0.25, the orientation-induced crystallization occurred. The fibers obtained in this region were characterized by the formation of the crystalline structure dominated by the β form. The presence of the necklike deformation in the spinning line was also confirmed. The solidification temperature of the spinning line analyzed from the diameter profile suggested that the formation of β modification crystals occurred at relatively low crystallization temperatures in comparison with that in an isotropic state. Therefore it was indicated that the presence of elongational stress in the spinning line promoted the formation of the β modification crystals. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 1415–1427, 1997

Effect of Extraordinary Large Diameter Nozzle in High-speed Melt Spinning of Poly(ethylene terephthalate).

High-speed melt spinning of poly (ethylene terephthalate) was performed using a nozzle with extraordinary large diameter of 5mm. A metallic porous filter was set in the nozzle to maintain high extrusion pressure. The structure of the as-spun fibers was compared with the fibers prepared using an ordinary nozzle. The molecular orientation of fibers spun at low take-up velocities, where orientation-induced crystallization did not take place, increrased by enlarging the nozzle diameter. The orientation-induced crystallization started at lower take-up velocities because of enhanced molecular orientation. On the other hand, the structure of crystallized fibers obtained at high take-up velocities was characterized by high crystallinity and relatively low molecular orientation. The on-line measurement of spinline velocity for the take-up velocity of 5km/min revealed that, in comparison with the spinning with ordinary nozzle, the spinline velocity increased more steeply near the spinneret and the solidification of the spinline occurred at a position closer to the spinneret. The solidification temperature, i. e. the crystallization temperature, estimated from the measured velocity profile also increased by enlarging the nozzle diameter. These changes were attributed to increase in temperature difference between center and surface of the spinline, which might lead to the stress concentration and the promotion of orientation-induced crystallization in the skin layer.

Fiber structure formation in high-speed melt spinning of poly(phenylene sulfide).

Fiber structure formation in high-speed melt spinning of poly(phenylene sulfide).

Effects of sodium stearate as a nucleating additive in high-speed melt spinning of poly(ethylene terephthalate).

Effects of sodium stearate as a nucleating additive in high-speed melt spinning of poly(ethylene terephthalate).