Variable-temperature study of a gel-spun ultra-high molecular-mass polyethylene fiber by solid state NMR

Cheng, Jin; Fone, Matilda; Fu, Yigang; Chen, Wei

doi:10.1007/bf01981803

Cited by 9 publications

(7 citation statements)

References 10 publications

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“…In transverse sections, cratering is visible, and in longitudinal sections, extended, density‐deficient regions between the macrofibrils can be seen. With solid‐state NMR, it was found that with heating from 295 to 413 K, 40 K above the analyzed annealing temperature used here, only small decreases in the mass fraction of the orthorhombic phase could be observed, and the oriented intermediate phase increased, whereas any monoclinic phase disappeared before 373 K was reached 22. Electron microscopy on conventional PE fibers with a low draw ratio of 11 recrystallize on annealing at 393 K on the surface of ribbon‐shaped macrofibrils into a network of lamellar crystallites 23.…”

Section: Introductionmentioning

confidence: 74%

Annealing behavior of gel‐spun polyethylene fibers at temperatures lower than needed for significant shrinkage

Бузин

Lin

et al. 2003

J Polym Sci B Polym Phys

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The annealing at 373 K of ultrastrong, gel-spun polyethylene (PE) has been studied. At this temperature, the fibers show no significant shrinkage. Still, a significant decrease in the mechanical properties is observed. The fibers have been analyzed with differential scanning calorimetry (DSC), temperature-modulated differential scanning calorimetry (TMDSC), atomic force microscopy (AFM), and small-angle X-ray scattering (SAXS). During the annealing, the glass transition of the intermediate phase is exceeded, as shown by DSC. When split for structure analysis by AFM, the annealed fibers undergo plastic deformation around the base fibrils instead of brittle fracture. The quasi-isothermal TMDSC experiments are compared to the minor structural changes seen with SAXS and AFM. The loss of performance of the PE fibers at 373 K is suggested to be caused by the oriented intermediate phase, and not by major changes in the structure or morphology. The overall metastable, semicrystalline structure is shown by TMDSC to posses local regions that can melt reversibly.

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Section: Introductionmentioning

confidence: 74%

Annealing behavior of gel‐spun polyethylene fibers at temperatures lower than needed for significant shrinkage

Бузин

Lin

et al. 2003

J Polym Sci B Polym Phys

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show abstract

“…The molecular structure and properties of polyethylene have been the subject of many interesting and useful studies including X‐ray diffraction,9–15 Optical analysis,16–17 Thermal analysis,18–21 NMR,22–24 Infra‐red analysis,25–32 Raman analysis,33–35 and Mechanical modeling 36. In particular, Hsieh and Hu,10 using high‐temperature wide‐angle X‐ray diffraction method, showed that the tension along the fiber axis direction encourages the structural transformation from the orthorhombic to the monoclinic phase.…”

Section: Introductionmentioning

confidence: 99%

Molecular structure and orientation of gel‐spun polyethylene fibers

Karacan

2006

J of Applied Polymer Sci

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Characterization of molecular structure and orientation of six commercially available gel-spun polyethylene fibers have been carried out using infra-red and Raman spectroscopy, thermal and X-ray diffraction analysis, together with optical microscopy techniques. Thermal and X-ray diffraction analysis revealed the existence of highly oriented orthorhombic and monoclinic crystallites together with a highly oriented intermediate phase known as pseudohexagonal mesophase structure. The results suggest the existence of a three-phase structure consisting, at room temperature, of orthorhombic and monoclinic polymorphic crystallites, oriented noncrystalline and un-oriented noncrystalline (amorphous) phases, respectively. The crystallinity measurements have been carried out using density, thermal and X-ray diffraction analysis together with infra-red and Raman spectroscopy techniques whereas the molecular orientation measurements have been carried out using birefringence and polarized IR spectroscopy, respectively. The results obtained from density, thermal analysis, and Raman spectroscopy based on a simple two-phase modeling approach lead to the overestimated amorphous fractions and appears to ignore the presence of an intermediate phase known as oriented noncrystalline structure. X-ray analysis has also been used for the measurement of the apparent crystallite sizes. The birefringence values have been used to determine the overall orientation parameters whereas the dichroic measurements of IR bands have been used to determine the crystalline and oriented noncrystalline orientation parameters. The results show that the orthorhombic and monoclinic phases are more highly oriented than the oriented pseudohexagonally packed noncrystalline chains.

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“…Structural composites with high strengths and low densities that are made from fibers such as aramid, carbon fibers, and high‐strength polyethylene (HSPE) fibers are beginning to be used routinely in place of more conventional metals and metallic alloys 1–3. HSPE fibers, composite‐reinforced fibers, are made of ultra‐high‐molecular‐weight polyethylene with a gel spinning method 4–6. The fibers exhibit the highest specific strength in manufactured fibers and are an important candidate fiber.…”

Section: Introductionmentioning

confidence: 99%

Grafting of multifunctional groups onto the surface of high‐strength polyethylene fibers and the interface of their composites

Chen

2005

J of Applied Polymer Sci

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High-strength polyethylene (HSPE) fibers were oxidated via chemical reactions in an acidic medium, and the carboxyl group was transferred into the acyl chloride and then reacted with pentaerythritol or diethylene triamine to graft the multifunctional group compounds onto the surface of the HSPE fibers. Subtractive Fourier transform infrared spectroscopy and the methylene blue absorbing method were used to study the functional groups on the surface of the modified fibers and their content. The results show that the polar functional groups, including OCOOH, OOH, and ONH 2 , were introduced onto the surface of the HSPE fibers, and the polar groups improved the wettability. The interface shear stress (IFSS) of the composites that were made from modified fibers and epoxy was measured by means of the microdebond method. The results show that the IFSS was greatly increased by the grafting of pentaerythritol or diethylene triamine onto the HSPE fiber surface.

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Variable-temperature study of a gel-spun ultra-high molecular-mass polyethylene fiber by solid state NMR

Cited by 9 publications

References 10 publications

Annealing behavior of gel‐spun polyethylene fibers at temperatures lower than needed for significant shrinkage

Annealing behavior of gel‐spun polyethylene fibers at temperatures lower than needed for significant shrinkage

Molecular structure and orientation of gel‐spun polyethylene fibers

Grafting of multifunctional groups onto the surface of high‐strength polyethylene fibers and the interface of their composites

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