Reaction mechanisms of polyacrylonitrile on thermal treatment

Kim, J.; Kim, Y. C.; Ahn, WonSool; Kim, C. Y.

doi:10.1002/pen.760332203

Cited by 53 publications

(51 citation statements)

References 25 publications

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“…PAN molecules are cyclized to transform into a non-meltable ladder structure, which is critical to avoid melting during carbonization [4]. It is known that nitrile groups in PAN are initiated thermally through a free radical mechanism, leading to cyclized network of hexagonal carbon-nitrogen rings [5]. Further, the nitrile groups in PAN with a large dipole provide high cohesive energy density and chain stiffness, which result in excellent tensile strength [6].…”

Section: Introductionmentioning

confidence: 99%

“…Further, the nitrile groups in PAN with a large dipole provide high cohesive energy density and chain stiffness, which result in excellent tensile strength [6]. Commercially, PAN precursors are polymerized with acidic comonomers such as acrylic acid, methacrylic acid, and itaconic acid [5]. Stabilization is one of the most important factors to determine mechanical strength of PAN based carbon fibers.…”

Section: Introductionmentioning

confidence: 99%

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Structural Evolution of Polyacrylonitrile Fibers in Stabilization and Carbonization

Lee¹,

Kim²,

Ku³

et al. 2012

ACES

200

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The effect of structural evolution polyacrylonitrile (PAN) on mechanical properties was investigated in stabilization and carbonization. PAN spun fibers were stabilized in a convection oven with a constant tension for various times at 250˚C. Fourier Transform Infrared spectroscopy (FTIR) and gel fraction results suggested that intra and intermolecular stabilization reactions occurred simultaneously. X-ray diffractograms revealed a disruption of crystalline structure and an appearance of pre-graphitic structure of PAN fibers due to stabilization. These structural changes by stabilization resulted in the significant decrease of tensile properties of fibers. In Raman spectra with heat treated fibers from 400˚C up to 1200˚C, the intensity ratio of the D to G bands (I D /I G ) decreased as heat treatment temperature increased, indicating an increase of basal plane of graphitic layer of heat treated fibers. Tensile strength of heat treated fibers at 1200˚C was found to be as high as 2.2 GPa.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structural Evolution of Polyacrylonitrile Fibers in Stabilization and Carbonization

Lee¹,

Kim²,

Ku³

et al. 2012

ACES

200

View full text Add to dashboard Cite

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“…Deionized water was used for preparation and dilution of reagents and samples.All monomers were purified to remove inhibitor before they were used using the prescribed procedure in literature [11] …”

Section: Methodsmentioning

confidence: 99%

Synthesis, Characterization and Thermal Degradation Studies of Acrylic Based Nanocomposite Polymeric Materials

2015

International Academy of Engineers Feb. 8-9, 2015 Kuala Lumpur (Malaysia)

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Abstract-Acrylic based polymeric nanocomposites have been synthesized with the incorporation of sodium montmorillonite and surface modified nanoclay to the extent of less than 1 wt% via in-situ intercalation method using N 2 gas as an inert media. The synthesized samples were characterized by X-Ray Diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The XRD analysis shows that diffraction peaks in the low angle region are absent which indicate that the d-spacing of ordered intercalated and ordered delaminated nanocomposites has not been achieved but the diffraction peaks has been shifted to larger 2-theta values which is an indication to the fact that disordered nanocomposites has been synthesized due to changes in the structure of the layers of the clay. But diffraction peaks of surface modified MMT and simple MMT has been shifted to lower angles in polymer and co-polymer nanocompisites, an indication to intercalated composite. In all the XRD graphs of pure polymeric substances and PNC'S, the peaks associated with [010] plane of a hexagonal structure which appeared at 2θ values of ~17˚confirm the crystalline structure of polyacrylonitrile. The diffraction angles at 29 o in pure polyacrylonitrile indicate the pre-graphitic type structure having a bragg's plane of [300].

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“…PAN molecules are cyclized to transform into a non-meltable ladder structure, which is critical to avoid melting during carbonization [4]. It is known that nitrile groups in homo PAN are initiated thermally through a free radical mechanism, leading to cyclized network of hexagonal carbon-nitrogen rings [5]. Furthermore, the nitrile groups in PAN with a large dipole provide high cohesive energy density and chain stiffness, which result in excellent tensile strength [6].…”

Section: Introductionmentioning

confidence: 99%

Effect of Process Condition on Tensile Properties of Carbon Fiber

Lee¹,

Kim²,

Ku³

et al. 2011

Carbon letters

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For polyacrylonitrile (PAN) based carbon fiber (CF) process, we developed a lab scale wet spinning line and a continuous tailor-made stabilization system with ten columns for controlling temperature profile. PAN precursor was spun with a different spinning rate. PAN spun fibers were stabilized with a total duration of 45 to 110 min at a given temperature profile. Furthermore, a stabilization temperature profile was varied with the last column temperature from 230 to 275 o C. Stabilized fibers were carbonized in nitrogen atmosphere at 1200 o C in a furnace. Morphologies of spun and CFs were observed using optical and scanning electron microscopy, respectively. Tensile properties of resulting CFs were measured. The results revealed that process conditions such as spinning rate, stabilization time, and temperature profile affect microstructure and tensile properties of CFs significantly.

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Reaction mechanisms of polyacrylonitrile on thermal treatment

Cited by 53 publications

References 25 publications

Structural Evolution of Polyacrylonitrile Fibers in Stabilization and Carbonization

Structural Evolution of Polyacrylonitrile Fibers in Stabilization and Carbonization

Synthesis, Characterization and Thermal Degradation Studies of Acrylic Based Nanocomposite Polymeric Materials

Effect of Process Condition on Tensile Properties of Carbon Fiber

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