The microstructure of PAN-base carbon fibres

Perret, R.; Ruland, W.

doi:10.1107/s0021889870006805

Cited by 191 publications

(90 citation statements)

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“…SAXS studies on bundles of carbon fibers have also been reported by Perret & Ruland (1970). Two types of intensity measurements were selected: intensity measurements perpendicular to the fiber axis with an infinitely long slit (Kratky camera) parallel to the fiber axis, shown schematically on the left-hand side of Fig.…”

Section: Introductionmentioning

confidence: 99%

Small-angle X-ray scattering in carbon fibers

Gupta¹,

Harrison²,

Lahijani³

1994

J Appl Crystallogr

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Small-angle X-ray scattering (SAXS) has been used as an analytical tool to study microporosity in polyacrylonitrile-(PAN-) and pitch-based carbon fibers. Microporosity in carbon fibers consists primarily of needle-shaped voids whose long axes are oriented preferentially along the fiber axis. This preferred orientation is seen to be independent of the nature of the fiber precursor and is the major deciding factor in controlling the modulus of carbon fibers. As the modulus increases, the general trend for both PAN-and pitchbased fibers is to move from a system consisting of many small pores to one with few larger pores. At very small angles, the steep rise in scattered intensity is due to reflection effects for PAN-based fibers and multiple scattering effects from voids for pitch-based fibers.in which ribbons of crystallites were aligned parallel to the fiber axis. The irregular contours of these crystailites create voids that are long and narrow or slit shaped and have a preferred orientation along the fiber axis. The SAXS pattern of such a structure shows a fanlike scattering along the equator. Fig. 2 is a schematic representation of the intensity distribution of SAXS in reciprocal space for a carbon fiber of high HTT and moderate preferred orientation. If one assumes that the fan-like intensity distribution is produced by a random distribution of needle-like pores with a preferred orientation of the principal axes of the pores lying parallel to the fiber axis, then the intensity distribution in reciprocal space consists of a distribution of discs centered on the origin of reciprocal space with disc normals lying

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Section: Introductionmentioning

confidence: 99%

Small-angle X-ray scattering in carbon fibers

Gupta¹,

Harrison²,

Lahijani³

1994

J Appl Crystallogr

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“…The radius of the rod-like flowinduced structures can thus be obtained as ðR c Þ 1=2 and is about 30 nm. The length L of the rod-like flow-induced scatterers can be calculated using Ruland's model (Perret & Ruland, 1969, 1970Ruland, 1969), according to which the azimuthal breadth of the equatorial streak (B obs ) is the sum of a contribution arising from the finite size of the scatterers (1/Ls) and a contribution arising from object misalignment (B or ): Polymer crystallization studies at DUBBLE 1687 Figure 7 Two-dimensional SAXS images of i-PP crystallized after the application of a shear pulse and at different apparent wall stresses. For w = 0.19 MPa, the best fit of the Ruland model suggests that the average length of the scatterers is about 290 nm (Fig.…”

Section: Shear-induced Crystallization Using a Slit Rheometermentioning

confidence: 99%

Polymer crystallization studies under processing-relevant conditions at the SAXS/WAXS DUBBLE beamline at the ESRF

et al. 2013

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Recent developments on the experimental infrastructure and the acquisition of new detectors on the Dutch-Belgian beamline BM26B at the ESRF offer novel and promising possibilities for synchrotron X-ray experiments in the field of polymer crystallization under processing-relevant conditions. In this contribution, some of the most recent experiments mimicking conditions similar to those relevant for the plastics processing industry are discussed. Simultaneous thermal analysis and wide-angle X-ray scattering (WAXS) experiments, at the millisecond time-frame level, on -nucleated isotactic polypropylene (i-PP) samples subjected to ballistic cooling up to 230 K s À1 , show that the efficiency of the nucleating agent can be suppressed when quenched cooling rates higher than 130 K s À1 are used. In situ WAXS experiments using small-scale industrial equipment during a real film blowing process reveal the dependence of the onset of crystallinity (the so-called freeze line) and the crystal orientation as a function of different take-up and blow-up ratios. In situ small-angle X-ray scattering (SAXS) experiments during high-flow fields reveal the formation of shish and kebab structures in i-PP as a function of the imposed stress. Quantitative analysis of i-PP flow-induced structures is presented. The beamline specifications required to obtain high quality and industrially relevant results are also briefly reported.

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“…Further, Lc is dependent on the orientation of the crystallite, and this dependency is emphasized at higher carbonization temperatures. Larger crystallite dimensions of the more-aligned domains have been reported earlier [25], and has ben attributed to the smaller thickness of misaligned graphitic planes that interlink the more-aligned domains in the ribbon model. It is also possible that enhanced crystallite growth of the aligned domains, caused by the existing preferential orientation of molecules in the stabilized fiber, results in orientation-dependent crystallite size.…”

Section: Results From Wide-angle X-ray Diffraction Studiesmentioning

confidence: 74%

Precursor Structure - Fiber Property Relationships in Polyacrylonitrile- Based Carbon Fibers

Abhiraman¹

1992

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The microstructure of PAN-base carbon fibres

Cited by 191 publications

References 0 publications

Small-angle X-ray scattering in carbon fibers

Small-angle X-ray scattering in carbon fibers

Polymer crystallization studies under processing-relevant conditions at the SAXS/WAXS DUBBLE beamline at the ESRF

Precursor Structure - Fiber Property Relationships in Polyacrylonitrile- Based Carbon Fibers

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