Electron-microscopical and electron diffraction study of the deformation of thin films of spherulitic polyvinylidenefluoride

Gal'perin, Ye.L.; Mindrul, V.F.; Smirnov, V. K.

doi:10.1016/0032-3950(70)90450-8

Cited by 15 publications

(2 citation statements)

References 11 publications

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“…Figure 2(A) shows the X-ray diffraction pattern of a nonoriented PVDF sample, with the assignment of the different crystal reflections of the ␣ and ␤ phases, [9][10][11][12] and provides a comparison with the X-ray diffraction patterns of the blue processed PVDF suture fiber oriented at X = 90°and 0°[ Fig. 2(B, C), respectively].…”

Section: Resultsmentioning

confidence: 99%

“…Identification of the crystalline planes was carried out using X-ray data previously published on PVDF. [9][10][11][12] Orientation was measured by azimutal rotation of the sample about the normal to its surface, from X = −90°to 90°at a rotating rate of 0.5°/15 s, with the goniometer located at the Bragg angle (2) corresponding to the crystalline plane of interest (X = 0 is defined as the fiber axis).…”

Section: Methodsmentioning

confidence: 99%

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Identification and quantification of the crystalline structures of poly(vinylidene fluoride) sutures by wide-angle X-ray scattering and differential scanning calorimetry

Laroche

Lafrance

Prud’homme

et al. 1998

J. Biomed. Mater. Res.

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The outstanding biocompatibility of the polyvinylidene fluoride (PVDF) monofilament suture together with other desirable characteristics, such as ease of handling and resistance to biodegradation, makes it an attractive alternative monofilament suture material for cardiovascular surgery. However, to achieve a high performance suture, the polymeric raw material must be exposed to different treatments, which lead to different degrees and types of crystallization. Since these crystalline modifications deeply influence the mechanical characteristics and the biostability of the sutures, the authors hereby propose a method of quantifying the different structures of PVDF using wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). The commercial devices are achieved by coloring and processing the polymeric raw material. The white and unprocessed 4-0 unswaged suture presents 19% of the alpha phase, 38% of the beta structure, and no gamma form. Coloration increases the amount of the beta phase by 5-9% at the expense of the alpha phase. On the other hand, processing the fibers lead to the conversion of some of the amorphous phase to the gamma structure, the importance of which is 6-7%. Finally, tensile measurements performed on the different PVDF fibers clearly proves that their mechanical characteristics depend on the presence of these crystalline forms in the polymeric structure of PVDF.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Identification and quantification of the crystalline structures of poly(vinylidene fluoride) sutures by wide-angle X-ray scattering and differential scanning calorimetry

Laroche

Lafrance

Prud’homme

et al. 1998

J. Biomed. Mater. Res.

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Microfibers within fibers: A review

Tucker

George

1972

Polymer Engineering & Sci

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Literature relating to the fundamental nature of the fibrous state is reviewed with the goal of illustrating evidence for the existence of a possibly fundamental morphological unit, the elemental microfiber or fibril. Following a short summary of the rather well documented situation in natural fibers, the problem of the microfiber in synthetic fibers is probed in terms of phenomena in solution and bulk polymeric systems. The reviewed literature indicates the existence of unique, elemental microfibers in synthetic fibers is largely tenuous; however, there is wide evidence of the existence of complex elongated structures axially aligned within macrofibers which future work may resolve into a central microfiber. The structural complexity appears to simplify for transformations occurring in high shear fields. This review covers articles through 1971, and it is notable that in 1971 approximately 100 articles of high relevance appeared in major journals.

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Polymer fibers drawn to the limit

Slutsker¹,

Utevskii

1984

J. Polym. Sci. Polym. Phys. Ed.

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The orientational drawing of polymers is known to be terminated because of sample rupture. The limiting draw ratio λlim reached may be different (either large or small) depending on the polymer and the actual drawing conditions. The purpose of the present work is to identify the change of supermolecular structure of polymer fibers which results in the termination of orientational drawing. Small‐and wide‐angle x‐ray diffraction were used to study the variation of geometrical parameters of this structure with increasing draw ratio λ. The geometrical parameters discussed are the dispersions (fluctuation) of long periods and of longitudinal sizes of crystalline as well as amorphous regions. In this study we used fibers of poly(vinyl alcohol), poly(ε‐caprolactam), polyoxymethylene, and poly(4,4′‐diphenyloxide) pyromellitimide. It is found that the long period dispersion of these polymers, drawn under different conditions, increases to approximately the same value for different samples drawn to the limit, this relative standard deviation δL of long periods being 0.30‐0.40. It is also found that the crystallite size dispersion does not increase with increasing λ; the increase of λL is due to increasing dispersion of the amorphous region lengths. For poly(vinyl alcohol) fibers drawn to the limit under different conditions and which have different λlim, the relative standard deviation of the sizes of amorphous regions δA turned out to be about the same (ca. 0.60). The latter evidence gives grounds to suggest that the rupture of polymers under drawing is associated with reaching a high degree of amorphous region size dispersion. In those regions which are considerably below the average size there probably will appear local overstress and molecular ruptures because the relative deformation of these regions is much larger than that of the adjacent regions in the cross section of the sample.

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Electron-microscopical and electron diffraction study of the deformation of thin films of spherulitic polyvinylidenefluoride

Cited by 15 publications

References 11 publications

Identification and quantification of the crystalline structures of poly(vinylidene fluoride) sutures by wide-angle X-ray scattering and differential scanning calorimetry

Identification and quantification of the crystalline structures of poly(vinylidene fluoride) sutures by wide-angle X-ray scattering and differential scanning calorimetry

Microfibers within fibers: A review

Polymer fibers drawn to the limit

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