Nature of the Crystalline and Amorphous Phases in Oriented Polymers and Their Influence on Physical Properties

Gupta, V. B.

doi:10.1002/9783527615056.ch11

Cited by 2 publications

(2 citation statements)

References 69 publications

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“…In this way, the interaction between molecules is maximized by minimizing chain-folding and local misalignments. Because of the high alignment, covalent bonds will be loaded next to the weaker van der Waals bonds and fibers end up with highly anisotropic properties (e.g., axial stiffness much larger than transversal). , In the ideal case, when all molecules are perfectly aligned, the total interaction between neighboring molecules is limited only by their length or, in other words, by their molecular weight. For this reason, the strongest fibers are realized by means of high-molecular-weight polymers …”

Section: Introductionmentioning

confidence: 99%

Multiscale Structure and Microscopic Deformation Mechanisms of Gel-Spun Ultrahigh-Molecular-Weight Polyethylene Fibers

et al. 2019

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We investigate the molecular features of high-performance gel-spun ultrahigh-molecular-weight polyethylene UHMWPE fibers (SK75, invented and manufactured by DSM) and propose a multiscale structural model that describes the organization of molecules from the unit cell to the filament level, based on X-ray diffraction in static and dynamic conditions (during tensile testing). The model emphasizes the discontinuous nature of the crystalline phase, which is embedded in a percolating amorphous phase and connected by tie molecules running through the amorphous phase. The tie molecules play a critical role in the tensile properties (e.g., Young’s modulus and sonic modulus) of the material. We analyze the micromechanics of the material during tensile deformation and show that, in the elastic regime, the stress-transfer mechanisms (e.g., tie molecules) are so efficient to realize a homogeneous stress distribution through the various length scales (from filament level to unit cell level). Plastic deformation of filaments begins with shear break-up of crystals that triggers or is triggered by an unusual, not well explored, deformation mode of the orthorhombic unit cell (contraction of the a-axis with simultaneous expansion of the b-axis). We also show that the morphological model with discontinuous crystalline phase provides a logical base for the interpretation of the sonic modulus of UHMWPE fibers. Realignment of molecules in the noncrystalline regions of the material can explain the remarkable increase of the sonic modulus measured during tensile tests.

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Section: Introductionmentioning

confidence: 99%

Multiscale Structure and Microscopic Deformation Mechanisms of Gel-Spun Ultrahigh-Molecular-Weight Polyethylene Fibers

et al. 2019

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“…Moreover, there is not a clear explanation of the combined effect caused by variable mechanical and thermal treatments on the deformation and the crystallization of oriented and initially non-crystallized polymers. [7,8] The aim of this paper is to investigate the structural developments in oriented PET occurring at a constant strain and heating in non-isothermal conditions.…”

Section: Introductionmentioning

confidence: 99%

Study of As-Spun Poly(ethylene terephthalate) Fibers Subjected to Thermal and Mechanical Treatments

Velev

Androsch

Radusch

et al. 2001

Macromol. Mater. Eng.

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Nature of the Crystalline and Amorphous Phases in Oriented Polymers and Their Influence on Physical Properties

Cited by 2 publications

References 69 publications

Multiscale Structure and Microscopic Deformation Mechanisms of Gel-Spun Ultrahigh-Molecular-Weight Polyethylene Fibers

Multiscale Structure and Microscopic Deformation Mechanisms of Gel-Spun Ultrahigh-Molecular-Weight Polyethylene Fibers

Study of As-Spun Poly(ethylene terephthalate) Fibers Subjected to Thermal and Mechanical Treatments

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