17. Solvent extracted pitch precursors for carbon fiber

Riggs, Dennis M; Diefendorf, R. J.

doi:10.1016/0008-6223(84)90234-3

Cited by 4 publications

(3 citation statements)

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“…31 The thermal conversion of petroleum pitch to mesophase involves both chemical polymerization and de-alkylation reactions. [32][33][34] Hence, the development in the pitch of long-range molecular order was attributed to both increasing molecular weight 32,33 and loss of sp 3 type chemical bonding (side chains on aromatic rings). 34 Such chemical reactions remove mesophase inhibitors and disordering species and lead to the formation of large planar molecules.…”

Section: Brooks and Taylor Mesophasementioning

confidence: 99%

“…[32][33][34] Hence, the development in the pitch of long-range molecular order was attributed to both increasing molecular weight 32,33 and loss of sp 3 type chemical bonding (side chains on aromatic rings). 34 Such chemical reactions remove mesophase inhibitors and disordering species and lead to the formation of large planar molecules. Based on these data, it was subsequently determined that the de-alkylation reactions, which increase the aromaticity and molecular planarity of the pitch molecules, had only a minor influence on mesophase formation, whereas polymerization reactions, which increase the molecular size, had a major influence on mesophase development.…”

Section: Brooks and Taylor Mesophasementioning

confidence: 99%

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Anisotropy and mesophase formation towards carbon fibre production from coal tar and petroleum pitches: a review

Castro¹

2006

J. Braz. Chem. Soc.

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A mesofase é o fator determinante para se produzir as propriedades e microestruturas desejadas dos materiais de carbono. A remoção das moléculas mais leves é necessária para sua produção, mas o rendimento pode ser melhorado com a utilização de pressão ou oxidação, antes da remoção das mesmas. Piches anisotrópicos podem ser produzidos através das tradicionais esferas de mesofase de Brooks e Taylor, ricas em resinas α, ou evitando-se as mesmas, através de outras técnicas, como a extração com solventes ou agitação intensa, para gerar, quase que exclusivamente, as resinas β. Piches anisotrópicos, contendo valores próximos a 100% de resinas β, têm sido fiados a temperaturas mais baixas, produzindo fibras de carbono de piche de maior qualidade. Estudos recentes mostraram, experimentalmente, porque os piches exibem comportamentos tão diferentes, no que diz respeito à produção da fibra de carbono, quando suas composições variam em termos de resinas α e β.Mesophase is a key issue to design carbon materials towards its properties and microstructures. The understanding of this intermediate phase has changed since it was first discovered. The removal of light molecules is necessary to produce mesophase, but the yield can be improved if other techniques, such as pressure and oxidation, can be used before they are carried out of the system, with nitrogen or vacuum. Anisotropic pitches can be produced throughout the traditional Brooks and Taylor mesophase spheres, rich in α-resins, or, avoiding them, with other techniques, such as solvent extraction or strong agitation, to generate, almost exclusively, β-resins. Anisotropic pitches exhibiting almost 100% β-resins have been meltspun at lower temperatures, producing pitch carbon fibres of higher quality. Recent studies were able to explain why the behaviour of the pitches is so different, towards the pitch carbon fibre production, when their compositions, in terms of α-resins and β-resins, change.

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Section: Brooks and Taylor Mesophasementioning

confidence: 99%

Section: Brooks and Taylor Mesophasementioning

confidence: 99%

Anisotropy and mesophase formation towards carbon fibre production from coal tar and petroleum pitches: a review

Castro¹

2006

J. Braz. Chem. Soc.

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“…In a 1980 patent assigned to Exxon, extraction with two typical solvents was disclosed as a method of separating a mesophase from a petroleum‐derived pitch mixture, by removing both the lightest and heaviest fractions 5. More recently, supercritical toluene has been used for this purpose 6…”

Section: Preparation Of Mesophase Pitchmentioning

confidence: 99%

Mesoscopic Structure and Properties of Liquid Crystalline Mesophase Pitch and Its Transformation into Carbon Fiber

Mochida

Yoon

Korai

2002

The Chemical Record

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The history and present state of the art in the chemistry of mesophase pitch, which is an important precursor for carbon fiber and other high-performance industrial carbons, are reviewed relative to their structural properties. The structural concepts in both microscopic and macroscopic views are summarized in terms of the sp(2) carbon hexagonal plane as a basic unit common to graphitic materials, its planar stacking in clusters, and cluster assembly into microdomains and domains, the latter of which reflect the isochromatic unit of optical anisotropy. Such a series of structural units is described in a semiquantitative manner corresponding to the same units of graphitic materials, although the size and stacking height of the hexagonal planes (graphitic sheets) are very different. Mesophase pitch is a liquid crystal material whose basic structural concepts are maintained in the temperature range of 250 to 350 degrees C. The melt flow and thermal properties are related to its micro- and mesoscopic structure. The structure of mesophase-pitch-based carbon fiber of high tensile strength, modulus, and thermal conductivity has been formed through spinning, and has inherited the same structural concepts of mesophase pitch. Stabilization settles the structure in successive heat treatments up to 3000 degrees C. Carbonization and graphitization enable growth of the hexagonal planes and their stacking into units of graphite. Such growth is governed and controlled by the alignment of micro- and mesoscopic structures in the mesophase pitch, which define the derived carbon materials as nanostructural materials. Their properties are controlled by the nanoscopic units that are expected to behave as nanomaterials when appropriately isolated or handled.

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Xylene activation of coal tar pitch binding characteristics for production of metallurgical quality briquettes from coke breeze

Zhong

Yang

Jiang

et al. 2016

Fuel Processing Technology

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17. Solvent extracted pitch precursors for carbon fiber

Cited by 4 publications

References 0 publications

Anisotropy and mesophase formation towards carbon fibre production from coal tar and petroleum pitches: a review

Anisotropy and mesophase formation towards carbon fibre production from coal tar and petroleum pitches: a review

Mesoscopic Structure and Properties of Liquid Crystalline Mesophase Pitch and Its Transformation into Carbon Fiber

Xylene activation of coal tar pitch binding characteristics for production of metallurgical quality briquettes from coke breeze

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