Morphology of Rigid-Rod Polymer Fibers: an Overview

Martin, David C.; Thomas, Edwin L.

doi:10.1557/proc-134-415

Cited by 11 publications

(6 citation statements)

References 52 publications

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“…However, previous studies report that the estimated ideal crystal density for PBO is higher than that measured for the actual fiber . In addition to this, microvoids have also been previously reported in the PBO fiber type. ,, Thus, the variations shown in Figure could be attributable to a core region with a lower content or a higher void density. To assess these possibilities, the variation in diffuse-background scattering across the fiber width can be determined.…”

Section: Theoretical Modelmentioning

confidence: 57%

“…Lattice imaging techniques have previously reported axial disruptions in the PBO crystal lattice . Equally, variations in chain packing could also affect the axial arrangement of molecules. ,,, Thus, in this study the term “structural order”, as measured from meridional scattering intensity, should be taken as representing a range of complimentary and competing morphological and crystallographic features.…”

Section: Theoretical Modelmentioning

confidence: 99%

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Modeling Structural Disorder within Single Poly(p-phenylenebenzobisoxazole) Fibers Using a Submicrometer Synchrotron Beam

Davies¹,

Burghammer²

2005

Macromolecules

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Scanning X-ray microdiffraction has been carried out across single polymeric fibers using a beam profile of 0.1 μm across the fiber axis. As-spun and heat-treated poly(p-phenylenebenzobisoxazole) (PBO) fibers have been studied to investigate the influence of heat treatment on fiber structure. Meridional “layer line” scattering intensity is observed to vary across the fiber width. This can be related to variations in the degree of structural order. Through the association of disordered regions with a layered morphology, a fiber model has been developed. The model proposes a three-layer fiber morphology with gradual transitions between layers. The core region can be offset from the geometric center of the fiber, and also be asymmetric. For fitting of the model to experimental data, a Monte Carlo simulation approach is employed. For both PBO fiber types, the fiber model provides a good fit to the experimental results obtained. The modeling results indicate that the heat treatment process causes a number of morphological changes within the fiber. These include a reduction in the thickness of the fiber skin and a distortion of the fiber core. Thus, the morphological core of the heat-treated fiber does not coincide with the geometric fiber center and is highly asymmetric. Several as yet unexplained results are also reported such as a larger core size in the heat-treated fiber type.

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Section: Theoretical Modelmentioning

confidence: 57%

Section: Theoretical Modelmentioning

confidence: 99%

Modeling Structural Disorder within Single Poly(p-phenylenebenzobisoxazole) Fibers Using a Submicrometer Synchrotron Beam

Davies¹,

Burghammer²

2005

Macromolecules

View full text Add to dashboard Cite

show abstract

“…Although inside the skin layer, the shape, size, and frequency of microvoids are similar to those in the core of PBO fibers, there is a void-free layer with thickness of approximately 0.2 µm in the top surface region (148). Figure 13 is the PBO fiber structural models suggested by (a) Martin (149) and (b) Kitagawa (148), respectively.…”

Section: Morphological Structuresmentioning

confidence: 98%

“…Some PAN-based carbon fibers also exhibit superior compressive strengths. Figure 23 is a typical stress-strain curve of PBO fibers under tension and compression (122,204). The yield stress in compression is only about one-tenth that in tension.…”

Section: Mechanical Optical and Other Propertiesmentioning

confidence: 99%

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Rigid‐Rod Polymers

Wang¹,

Jiang²,

Adams³

2011

Encyclopedia of Polymer Science and Technology

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Pursuing high strength and high modulus polymer fibers and novel electrooptical properties have motivated much research activity in rigid‐rod polymers in the past 40 years. In this review, we examine the synthesis, structures, and properties of rigid‐rod polymers with emphasis on polybenzobisoxazoles (PBO), polybenzobisthiazoles (PBZT) and polybenzimidazoles (PBI), beginning with their solution properties, especially lyotropic liquid crystallinity. High performance fibers spun from lyotropic liquid crystalline polyphosphoric acid (PPA) solution are described. The characterization of fiber properties including mechanical, thermal, electrical, and optical properties is summarized. PBO (Zylon) and PIPD (M5) fibers were successfully commercialized in high strength applications such as body armor, ropes, cables, and recreational equipment in the last 10 years, and we discuss the possible causes of rapid degradation of some PBO fibers. The concepts of molecular composites and nanocomposites provide new applications in antiballistic materials, fire protection, athletic equipment, cables, strings, ropes, cordage, sails, multilayer circuits, and catalyst supports. Recently, rigid‐rod polymer films have drawn attention in the electrooptical fields, especially for phosphoric acid (PA)‐doped PBI membranes (Celtec MEAs) in the applications of high temperature fuel cells. Computer simulation has been employed as a powerful tool to predict the properties of the rigid‐rod polymers.

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An analysis of capillary water behavior in poly‐p‐phenylenebenzobisoxazole fiber

Kitagawa

Yabuki

2001

J of Applied Polymer Sci

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ABSTRACT:This study concerns with analysis of water inside a poly-p-phenylenebenzobisoxazole (PBO) fiber. It is important to analyze the state of water attached to polymer, because it may affect properties of fibers as the increase of drying speed of water from the fiber. To carry out such observation, differential scanning calorimetry and nuclear magnetic resonance spectroscopy were applied. They reveal the large freezing point depression and the state of water inside wet PBO fiber. It shows extraordinary low crystallization temperature. The reason may be that the water is packed into capillary voids whose diameter is around 2-3 nm. Proton NMR analysis also suggests the above result.

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Morphology of Rigid-Rod Polymer Fibers: an Overview

Cited by 11 publications

References 52 publications

Modeling Structural Disorder within Single Poly(p-phenylenebenzobisoxazole) Fibers Using a Submicrometer Synchrotron Beam

Modeling Structural Disorder within Single Poly(p-phenylenebenzobisoxazole) Fibers Using a Submicrometer Synchrotron Beam

Rigid‐Rod Polymers

An analysis of capillary water behavior in poly‐p‐phenylenebenzobisoxazole fiber

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