25. Aromatic asphaltenes Part I. Asphaltenes of aromatic pitches

25. Aromatic asphaltenes Part I. Asphaltenes of aromatic pitches

205 Abstracts carbon/carbon matrices and bulk graphites. In this paper, the basic concepts of solubility theory will be briefly explored and used to ...

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205

Abstracts carbon/carbon matrices and bulk graphites. In this paper, the basic concepts of solubility theory will be briefly explored and used to postulate the existence of a “gradient” solution model for pitch. The results of various extraction conditions on the actual characteristics of the extracted products will also be discussed. Examples of how these extracted products perform as precursors for carbon fiber will be shown. lg. Phase behavior of mesomorphic binary systems R. J. Diefendorf (Materials Engineering Department, Rensselaer Polytechnic Institute, Troy, NY 12181, U.S.A.). ‘The phase diagrams for binary mesomorphic systems with differing miscibilities will be presented. Phase behavior with rod and discotic mesophases will also be discussed. The concepts developed are generalized to describe mesophase pitches as a pseudo binary system between a mesogen and a nonmesogen. 19. Mesophase formation in polynuclear aromatic compounds S-H. Chen and R. J. Diefendorf (Materials Engineering Department, Rensselaer Polytechnic Inforstitute, Troy, NY 12181, U.S.A.). Mesophase mation in the parapolyphenylene system was studied by hot stage microscopy and differential scanning calorimetry (DSC). Phase diagrams were constructed to derive the virtual mesophase-isotropic transition temperatures of the non-mesomorphic para-quater and terphenyl. The possibility of mesophase formation for a mixture of disc-like molecules was also investigated. 20. Pitch-mesophase-carbon transformation diagrams B. Rand and S. Whitehouse (Department of Ceramics, Glasses and Polymers, University of Shefield, Shefield SlO 2TZ, England). The concept of a transformation diagram to describe the pyrolysis of pitch to carbon via mesophase is outlined and experimental results presented. The diagram is constructed from characteristic temperatures such as temperatures of decomposition and glass transition temperatures of the different phases present plotted as some function of the extent of transformation to carbon such as C/H atomic ratio. 21. Solubility and reactivity of carbonaceous mesophase lsao Mochida, Keiko Maeda, Yozo Korai (Research institute of Industrial Science, Kyushu University, Kasuga 816, Japan). Solubilities and reactives of carbonaceous mesophases, which were prepared under variable conditions, were investigated in the co-carbonization with some additives. The solubility and reactivity are strongly independent upon the natures of mesophase as well as the additives. The mesophase produced at lower temperature consisting of lower molecular weight components are more soluble and reactive. The importance of hydrogen

transfer from the additive is another ture for the better solubility.

important

fea-

22. Volatilized compounds and microstructural development during mesophase growth in a pitch fraction I. W. Sorensen? and R. J. Diefendorf (Materials Engineering Department, Rensselaer Polytechnic Institute, Troy, NY 12181, U.S.A.). The tolueneinsoluble fraction of Ashland A-240 pitch was subjected to controlled heating in vacuum and argon. Material evolved and condensed in cooler parts of the furnace was removed and studied by HPLC. The observation of distinct chromatographic peaks was correlated with mesophase development within the pitch and independent studies on the fraction’s composition.

TPresently with Bendix Advanced Technology Center, Columbia, MD.

23. Anisotropic/isotropic coke precursors in decant oil E. W. Albaugh, J. D. Bacha, H. T. Best, W. E. Hartman, R. M. Henry, and K. S. Seshadri (Gulf Research & Development Company, P.O. Drawer 2038, Pittsburgh, PA 15320, U.S.A.) and G. B. Engle and R. J. Price (GA Technologies Inc., P.O. Box 81608, San Diego, CA 92138, U.S.A.). The chemical structural characteristics and pyrolytic behavior of preparative-scale liquid chromatographic fractions of a decant oil were correlated. Only those fractions containing condensed aromatics bearing few alkyl substituents or polar groups formed mesophase and anisotropic cokes. Fractions rich in highly alkylated aromatics or polar compounds failed to form mesophase and yielded isotropic cokes. 24. Mesophase formation from characterized pitch fractions (Part 2) E. Fitzer, C. Holley, L. Liu, T. Trendelenburg (Institut .fiir Chemische Technik, Universitat Karls12, 7500 Karlsruhe, FRG). ruhe, KaiserstaPe Pitches from various origins were fractionated by subsequential extraction and characterized. The mesophase formation behaviour was studied using classical optical and in-situ hot stage methods. These results are correlated with the analytical data. 25. Aromatic asphaltenes Part I. Asphaltenes of aromatic pitches Ghaz Dickakian (Exxon Enterprises, Greenville, South Carolina; Exxon Chemical Company, Florham Park, New Jersey, U.S.A.). Three highly aromatic pitches derived from petroleum (catalytic cracking residue), chemical (steam cracking residue) and coal (coal gasification) were fractionated by solvent extraction into C,-asphaltene and a deasphaltenated oil (DAO). The C,-asphaltene and the DA0 fractions were characterized (NMR, high-temperature GPC, coking

206

Abstracts

and thermal analysis) to define the role of each fraction in carbon anode manufacturing. The C,-asphaltene is the part of the pitch which will carbonize and produce the pitch-coke required for binding the petro or needle coke when manufacturing carbon or graphite anodes. The DA0 fraction is a volatile and non-coking. Its content and boiling characteristics (or molecular weight) effects the anisotropic structure development and the anode tensile strength. 26. Carbon fiber properties from solvent extracted pitch

D. M. Riggs and J. G. Venner (Exxon Enterprises Materials Division, Fountain Inn, SC 29644, U.S.A.). A process for producing pitch-based carbon fibers from solvent extracted pitches and distillates has been developed. The precursor carbonaceous materials are extracted at appropriate temperatures with solvents having overall solubility parameters preferentially in the range from about 8.e9.0 (Cal/cc)“‘. The extracted precursors are then melt spun, oxidized and carbonized. In this paper, the properties of these fibers will be discussed. It will be shown that at 1 mm gage lengths, strengths in excess of SOOKSI are obtained for fibers with moduli of 30MSI. The textures, flaw distributions, and effects of carbonizing temperatures on strength, modulus, density, crystallite dimensions and preferred orientations will also be given. 27. Investigations on pitch fractions by chemical and thermal treatments and their structural studies

R. L. Seth, K. K. Datta, C. L. Verma, C. La1 and V. P. Mittal (Carbon Technology Unit, National Physical Laboratory, New Delhi 110012, India). Chemical and thermal treatments of coaltar pitches and their saturated fractions with sulphur and oxygen influences distribution of CI, /? and y resins. The pitches and cokes formed by carbonization of the original and modified fractions have been investigated by physical techniques. Structural growth is more prominent in toluene soluble fraction. 28. The effect of shear on mesophase formation in A-240 pitch I. W. Sorensent

and R. J. Diefendorf (Materials Engineering Department, Rensselaer Polytechnic Znstitute, Troy, NY 12181, U.S.A.). The effect of shear on the heat-treatment of A-240 pitch was studied. The changes in the saturates, naphthene aromatics, polar aromatics, asphaltenes and pyridine insolubles were measured and compared to thermogravimetric results. Gel permeation chromatography also allowed determination of the changes in molecular weight distributions. These observations were correlated with the mesophase formation.

tPresently with Columbia, MD.

Bendix

Advanced

Technology

Center,

29. Rheological investigations of pitch constituents R. Busch, E. Fitzer (Znstitutfiir Chemische Technik, Universitiit Karlsruhe, FRG). The changes in the rheological behaviour of model polyaromatics, carbonized with AlCl,, to improve the carbonization properties, were investigated during HTT up to 500°C. It is attempted to correlate the rheological behaviour with the chemical composition of the pitch precursor and the molecular changes induced by crack- and polymerisation processes. 30. Needle coke precursors: chemical characteristics which affect needle coke formation

E. W. Albaugh, J. D. Bacha, H. T. Best, W. E. Hartman, R. M. Henry, and K. S. Seshadri (Gulf Research & Development Company, P.O. Drawer 2038, Pittsburgh, PA 15230, U.S.A. G. B. Engle and R. J. Price (GA Technologies Inc., P.O. Box 81608, San Diego, CA 92138, U.S.A.). A decant oil was pyrolyzed to 460°C the pyrolyzate solvent fractionated, and the needle coke forming potential of the fractions established. Comparison of the chemical sructural characteristics of the fractions with their carbonization tendencies indicated that the degree of alkyl substitution of condensed aromatics is a predominant factor affecting the type of coke formed. 31. Properties

of pyrolysis

residues

from selected

precursors

M. Benn, B. Rand and S. Whitehouse, (Department of Ceramics, Glasses and Polymers, University of Shefield SlO 2TZ, England). Glass transition temperatures (T,) are reported for pyrolysis products from four different precursors under varying pyrolysis conditions and at different extents of transformation to mesophase. At comparable stages of transformation faster heating results in products with lower Tg, which is attributed to retention of smaller molecules. 32. Free radicals in pitch pyrolysis H. Lopez, J. Calderon, J. Diaz, J. Rincon (Chemistry Department, National University of Colombia, Bogota). Coal tar and petroleum pitch fractions were carbonized to [email protected]”C in glass sealed tubes. Optical texture and ESR parameters of Carbons were monitored at room temperature. The results show that an increase of spin concentration during carbonization and narrow AHpp values lead to large optical texture in carbons. 33. Co-carbonizations

of a Solvent-Refined Coal with selected coal types-I. Thermoplasticity and optical texture development

Ching-Yi Tsai, William Spackman* and Alan W. Scaroni (Fuels and Combustion Laboratory, *Coal Research Section, The Pennsylvania State University, University Park, PA 16802, U.S.A.). When coals were co-carbonized with a Solvent-Refined Coal, thermoplastic behavior and optical texture development were modified substantially. The extent of increase in