Structural transformation of ultra-high modulus and molecular weight polyethylene fibers by high-temperature wide-angle X-ray diffraction

Hsieh, You‐Lo; Hu, Xiaoping

doi:10.1002/(sici)1099-0488(199703)35:4<623::aid-polb10>3.0.co;2-i

Cited by 50 publications

(49 citation statements)

References 6 publications

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“…They display very regular structures as indicated by their 1 H NMR spectra and DSC thermograms and shown by their corresponding XRD patterns. As a typical example, Figure 5 shows the diffractogram of polyester PE 12,26 with two main reflections at 2 θ ≈ 21.6° (110) and 24.1° (200) characteristic of a polyethylene like crystal structure 43, 44…”

Section: Resultsmentioning

confidence: 99%

Plant Oil‐Based Long‐Chain C₂₆ Monomers and Their Polymers

Vilela

Silvestre

Meier

2012

Macro Chemistry & Physics

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The self‐metathesis of erucic acid with ruthenium‐based catalysts, followed by the hydrogenation of the double bond, yielded 1,26‐hexacosanedioic acid (AA). Polycondensation of this biobased long‐chain α,ω‐dicarboxylic acid with hexacosane‐1,26‐diol (BB), generated from the former by reduction, yielded the polyester 26,26. Monomer AA was also polymerized with short‐chain alkanediols, namely dodecane‐1,12‐diol and butane‐1,4‐diol, generating polyesters 12,26 and 4,26, respectively. The properties of these aliphatic polyesters were investigated by various techniques, revealing high crystallinity, melting, and degradation temperatures, depending on the monomers used. These materials are an attractive alternative to fossil resource‐based polymeric materials.

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Section: Resultsmentioning

confidence: 99%

Plant Oil‐Based Long‐Chain C₂₆ Monomers and Their Polymers

Vilela

Silvestre

Meier

2012

Macro Chemistry & Physics

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“…2 The microstrain lattice distortion seemed predominantly present in UHMWPE fibers, owing to the generally linear relationship between 6{3 and h. For the single crystals and melt crystallized linear polyethylene, however, paracrystalline distortion was found to be predominant. 2 1.2 2 The reason is probably that there are not only small crystallite sizes and wide crystallite size distribution presented in gel-spun UHMWPE fibers, but also an intermediate phase which could give line broadening exists; whereas in single crystal polyethylene there are usually paracrystalline distortion governing the structure. The observation of dominant microstrain fibers is consistent with the results in Fu et al's 13 work.…”

Section: Resultsmentioning

confidence: 99%

“…The amount of non-crystalline domains is small, containing mainly chain entanglements, taut tie molecules, and chain ends. 2 The structure ofUHMWPE fibers has been extensively studied. 1 -20 Under ambient conditions, UHMWPE fibers mainly exhibit an orthorhombic crystalline structure with low levels of non-orthorhombic crystals.…”

mentioning

confidence: 99%

Crystallite Sizes and Lattice Distortions of Gel-Spun Ultra-High Molecular Weight Polyethylene Fibers

Hu¹,

Hsieh²

1998

Polym J

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ABSTRACT:A detailed method is reported for deriving the lattice distortions and crystallite sizes of ultra-high molecular weight polyethylene (UHMWPE) fibers employing a full wide angle X-ray diffraction (W AXD) pattern. The predominant crystals are orthorhombic form and the refined unit cell dimensions for a and b are 7.40( ± 0.03) and 4.94( ± 0.03) A, respectively.The average crystallite size normal to 110 planes was found to be in the range of 163-182A. The microstrain lattice distortion was predominant in the gel-spun UHMWPE fibers, with the lattice constant variation of 0.5%.KEY WORDS Ultra-High Molecular Weight Polyethylene I Wide Angle X-Ray Diffraction I Paracrystalline Structure I Lattice Distortion I Crystallite Size I Microstrain IThe gel-spun ultra-high molecular weight polyethylene (UHMWPE) fibers have superior mechanical properties with the Young's modulus and tensile strength in the range of 100---220 GPa and 3-6 GPa, respectively. 1 Such superior mechanical properties are ascribed to the highly oriented and fully extended chains in the highly crystalline structure. The amount of non-crystalline domains is small, containing mainly chain entanglements, taut tie molecules, and chain ends. 2 The structure ofUHMWPE fibers has been extensively studied. 1 -20 Under ambient conditions, UHMWPE fibers mainly exhibit an orthorhombic crystalline structure with low levels of non-orthorhombic crystals. 2 -4 • 13 Structural transformations have been observed on UHMWPE fibers. Tension along the fiber axis and lateral compression have shown to cause crystal transformation from the orthorhombic to the monoclinic form. 6 • 10 At either high pressure or the temperature close to its melting point, the orthorhombic crystals go through a solid-state phase transformation to the pseudohexagonal crystals. 3,4,10 The crystallite sizes and lattice distortions in UHMWPE fibers are not as well understood. The wide angle X-ray diffraction (W AXD) peak widths are known to be closely associated with crystallite sizes. The analysis of peak width is, however, cumbersome owing to the scattering contributions of the amorphous halo and the overlapping of multiple reflections. Valid measurements of the crystallite sizes can only be made when peak overlaps can be properly resolved and separated from the background scatter. Determination of background scattering is the most difficult task and the methods chosen can lead to different results. For instance, crystallite sizes and lattice distortion of the same UHMWPE fibers were different depending upon whether a straight-line background 6 or the Fourier transform background 13 was used. Before the line broadening is computed, corrections for air scattering, white light radiation, sample absorption, Lorentz and polarization, and Compton factors have to be made. Likewise the instrumental broadening which arises from the finite width of the slits, thickness of the sample, divergence of the incident beam and the spectral distribution of energy in the incident radiation has to be eliminated.T...

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“…There are many reports concerning the structure of nascent 6 and differently processed UHMWPE samples. 3,[7][8][9] The occurrence of polymorphism 3,7,[10][11][12] is characteristic for crystal part, the orthorhombic crystals lattice being the most typical. It was established that the crystal lamellae in both nascent and processed unoriented UHMWPE have similar dimensions, close to 20 nm on average.…”

Section: Ultrahighmentioning

confidence: 99%

“…8 There are reported some cases where a part of the typical, stable and prevailing orthorhombic crystals could be transformed into a monoclinic or transient hexagonal phase. 3, 7-11, 14, 15 Thus, monoclinic crystals are observed in highly deformed samples (fibers) [7][8][9][10] or in the samples crystallized under stress. 16 Moreover, there are experimental results showing that polyethylene crystals transform from the stable orthorhombic crystal into a transient hexagonal phase, observed when the polymer is subjected to the action of fast electrons 14 or at high pressure and temperature.…”

Section: Ultrahighmentioning

confidence: 99%

Mechanical Properties of Ultra High Molecular Weight Polyethylene Obtained with Different Cocatalyst Systems

Zamfirova

Pereña

Benavente

et al. 2002

Polym J

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ABSTRACT:Three types of semicrystalline ultra high molecular weight polyethylene, obtained with amorphous SiO 2 -supported Ziegler-Natta catalyst systems modified by vanadium and titanium, have been studied by wide angle XRay scattering, dynamic mechanical thermal analysis and microhardness methods. In all the cases a significant amount of monoclinic modification is observed, which is estimated to be of the order of 10%. With increasing the degree of crystallinity and quantity of entanglements, storage modulus and α relaxation increase and γ relaxation decreases. A weak β relaxation occurs only in the sample obtained with vanadium catalytic systems. Microhardness measurements give the possibility of distinguishing the effect of crystallinity from the effect of entanglements: Vickers microhardness is sensitive predominately to crystalline phase, while total microhardness is sensitive also to the structural peculiarities in the amorphous phase.KEY WORDS Ultrahigh Molecular Weight Polyethylene (UHMWPE) / Dynamic Mechanical Thermal Analysis (DMTA) / Wide-Angle X-Ray Diffraction (WAXS) / Microhardness / Ultrahigh Molecular Weight Polyethylene (UHMWPE) (M>10 6 ) possesses excellent mechanical properties and some advantages over conventional polyolefins as a high level of durability, excellent creep characteristics and abrasion resistance. [1][2][3][4][5] For this reason it is used in demanding applications such as artificial hip and knee joints, machine parts, fibres, polymer coating on metal surface, separators, acoustic diaphragms, etc.It is established that this semicrystallyne polymer has a specific morphology. There are many reports concerning the structure of nascent 6 and differently processed UHMWPE samples. 3,[7][8][9] The occurrence of polymorphism 3, 7, 10-12 is characteristic for crystal part, the orthorhombic crystals lattice being the most typical. It was established that the crystal lamellae in both nascent and processed unoriented UHMWPE have similar dimensions, close to 20 nm on average. 6 This thickness could be varied from 10 nm after necking 13 up to 100 nm in highly oriented fibres. 8 There are reported some cases where a part of the typical, stable and prevailing orthorhombic crystals could be transformed into a monoclinic or transient hexagonal phase. 3, 7-11, 14, 15 Thus, monoclinic crystals are observed in highly deformed samples (fibers) 7-10 or in the samples crystallized under stress. 16 Moreover, there are experimental results showing that polyethylene crystals transform from the stable orthorhombic crystal into a transient hexagonal phase, observed when the polymer is subjected to the action of fast electrons 14 or at high pressure and temperature. 3,15 Since the chain mobility is rather high in the hexagonal phase, sintering has been achieved via this transient phase. 3 There were found reports concerning to the study of the amorphous phase by NMR 8 and by positron annihilation lifetime spectroscopy. 17 It was reported a 5% of disordered all-trans interfacial material and/or tie molecu...

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Structural transformation of ultra-high modulus and molecular weight polyethylene fibers by high-temperature wide-angle X-ray diffraction

Cited by 50 publications

References 6 publications

Plant Oil‐Based Long‐Chain C₂₆ Monomers and Their Polymers

Plant Oil‐Based Long‐Chain C₂₆ Monomers and Their Polymers

Crystallite Sizes and Lattice Distortions of Gel-Spun Ultra-High Molecular Weight Polyethylene Fibers

Mechanical Properties of Ultra High Molecular Weight Polyethylene Obtained with Different Cocatalyst Systems

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Structural transformation of ultra-high modulus and molecular weight polyethylene fibers by high-temperature wide-angle X-ray diffraction

Cited by 50 publications

References 6 publications

Plant Oil‐Based Long‐Chain C26 Monomers and Their Polymers

Plant Oil‐Based Long‐Chain C26 Monomers and Their Polymers

Crystallite Sizes and Lattice Distortions of Gel-Spun Ultra-High Molecular Weight Polyethylene Fibers

Mechanical Properties of Ultra High Molecular Weight Polyethylene Obtained with Different Cocatalyst Systems

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Plant Oil‐Based Long‐Chain C₂₆ Monomers and Their Polymers

Plant Oil‐Based Long‐Chain C₂₆ Monomers and Their Polymers