Studies on the orientation phenomena by fiber formation from polymer melts. IV. Effect of molecular structure on orientation. Polyethylene and polystyrene

Ziabicki, Andrzej; Kedzierska, Krystyna

doi:10.1002/app.1962.070062114

Cited by 35 publications

(12 citation statements)

References 2 publications

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“…They found that the orientation as measured by the birefringence is directly proportional to the principal stress difference independent of the deformation mode. Figure 3 depicts Oda and others' data obtained from melt spinning, uniaxial extension, and shear deformation of polystyrene along with the polystyrene melt spinning data reported by Ziabicki and Kedzierska [ 16]. Clearly, birefringence varies linearly with the principal stress difference, which for melt spinning implies that C being the stress optical coefficient.…”

Section: Theoretical Backgroundmentioning

confidence: 88%

Identifying Critical Process Variables in Poly(ethylene Terephthalate) Melt Spinning 1

Dutta

Nadkarni

1984

Textile Research Journal

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A quantitative procedure for identifying critical operating conditions and material properties for the melt spinning of poly(ethylene terephthalate) (PET) is considered. The method is based on the experimental observation that for vitrified polymers like polystyrene and PET spun at speeds below 3000 m/minute, the molecular orientation of the as-spun fiber is uniquely determined by σ L , the spinline stress at the glass transition temperature. Using a constant tension model that predicts σ L , a sensitivity analysis of the fiber orientation to changes in process variables is investigated. Extrusion temperature, melt intrinsic viscosity, feed rate, and the takeup velocity are the key variables for PET melt spinning, as they strongly affect the freeze line location and the as-spun fiber orientation.The production of poly(ethylene terephthalate) (PET) fibers or filaments involves melt spinning of the molten polymer followed by solid state drawing and annealing. The final fiber properties such as tensile strength, elongation, shrinkage, and dyeability are determined by structural parameters such as orientation and crystallinity. The fiber morphology is the result of the combined influence of the spinning, drawing, and annealing steps. Although the desired orientation and crystallinity are achieved primarily through the control of process parameters in the drawing and annealing steps, the fiber-line processibility in terms of drawability and level of broken and fused filaments is determined by the orientation and uniformity in asspun fibers. Also the final product quality parameters such as the coefficient of variation of fiber denier and tenacity, level of overlength fibers, etc., are influenced mainly by controlling the spinning process variables. This is because the basic spatial arrangement of polymer molecules with respect to the fiber axis is formed in the melt spinning step.The orientation developed in the spinning threadline is the result of tensile deformation under stress in the flowing melt. The net orientation in the flowing melt is determined by the relative rates of extensional flow and the disorienting thermal relaxation phenomena. These rates are governed by the velocity and temperature variation along the threadline. Figure 1 shows a schematic representation of the melt spinning process. Molten polymer is extruded through a spinneret into FIGURE 1. A schematic representation of the melt spinning process. a quench air stream blowing across the spinline. The spinline so formed cools and finally solidifies at a distance from the spinneret known as the &dquo;freeze line.&dquo; The solidified filament is then wound on takeup rolls at a speed significantly greater than the extrusion velocity. This difference in speed causes the filament to stretch, and the final cross-sectional area is considerably smaller (about 100 to 200 times) than the initial extruded area. In the absence of crystallization in the spinline, the orientation of the solidified filament rep-' NCL Communication No. 3185.

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Section: Theoretical Backgroundmentioning

confidence: 88%

Identifying Critical Process Variables in Poly(ethylene Terephthalate) Melt Spinning 1

Dutta

Nadkarni

1984

Textile Research Journal

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“…Thus, it is inferred that the polymer chains were rearranged during the drawing process into a more ordered, anisotropic morphology with the chains aligned along the fiber axis (illustrated by the schematic drawing in the red circle in Figure a). This provides further evidence that the PPM chains are predominantly linear . Upon heating the fibers with a heating stage to 110 °C (above the glass transition temperature of PPM), the polymer fibers lost their birefringence irreversibly (cf.…”

Section: Resultsmentioning

confidence: 74%

Processing of the Multifunctional Polymer Poly(phenylene methylene) into Fibers, Films, Foams, and Microspheres

Braendle

Ofner

Perevedentsev

et al. 2019

Macro Materials & Eng

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Poly(phenylene methylene) (PPM) has recently emerged as a promising multifunctional polymer, requiring straightforward one‐step synthesis to achieve high molar mass and featuring a range of attractive properties. Its processability, however, has not been explored in detail to date. Therefore, this study presents a comprehensive investigation of the processability of PPM into a wide range of forms by employing various polymer processing techniques. Thin fibers (diameter ≈100 µm) over 1 km in length and shorter thick fibers (diameter ≈1 mm) are produced by melt spinning. Although no crystallinity is observed, the fibers surprisingly exhibit pronounced birefringence. The capability for waveguiding red light within the fibers is also demonstrated. Furthermore, films with a broad thickness range, spanning nanometer to millimeter length scales, are fabricated using different approaches such as spin‐coating, hot pressing, and die casting. All films feature a very smooth and crack‐free surface topography. Additionally, freestanding foams of PPM are obtained by foaming highly concentrated solutions, and quasi‐monodisperse microspheres are prepared by a microfluidic high‐throughput emulsification. The material properties of these different specimen forms are investigated and discussed for implementation as products ranging from plastic optical fibers and light emitting diodes, to protective coatings and packaging, as well as insulators and separation membranes.

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“…The first orientation measurements in elongational flow were reported by Zabicki and Kedzierska in the late 1950s, for different polymer melts leaving a circular spinneret [162][163][164]. In these early works, the role of elongation rate could not be separated from cooling effects and the results were explained by the formation of polymer threads upon solidification at the exit [162]. In these early works, the role of elongation rate could not be separated from cooling effects and the results were explained by the formation of polymer threads upon solidification at the exit [162].…”

Section: Affine Deformation Modelmentioning

confidence: 97%

“…Early interest in this flow geometry was connected with fiber-spinning mechanisms [161]. The first orientation measurements in elongational flow were reported by Zabicki and Kedzierska in the late 1950s, for different polymer melts leaving a circular spinneret [162][163][164]. From birefringence data, these authors determined that orientation was insignificant below a strain-rate of 0.5 S-l but increased rapidly with the gradient until saturation at about 10 S-l.…”

Section: Affine Deformation Modelmentioning

confidence: 99%

Flexible Polymer Chains in Elongational Flow

Nguyen¹,

Kausch²

1999

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Studies on the orientation phenomena by fiber formation from polymer melts. IV. Effect of molecular structure on orientation. Polyethylene and polystyrene

Cited by 35 publications

References 2 publications

Identifying Critical Process Variables in Poly(ethylene Terephthalate) Melt Spinning 1

Identifying Critical Process Variables in Poly(ethylene Terephthalate) Melt Spinning 1

Processing of the Multifunctional Polymer Poly(phenylene methylene) into Fibers, Films, Foams, and Microspheres

Flexible Polymer Chains in Elongational Flow

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