- Email: [email protected]
235. Microstructure of mesophase carbon fiber
150
Abstracts
226. Fiber-polymerinteractions in graphite fiber/polymer composites Y. S. Ko, W. Forsman and T. Dziemianowicz (Department of Chemical Engineering, University of Pennsylvania, Philadelphia, PA 19104). Dynamic mechanical measurements and short beam shear tests have been used to characterize an Epon 828/MPDA epoxy resin and its composites with types A and HM carbon fibers. T, of the unfilled resin is sensitive to both epoxy stoichiometry and curing schedule. Composite properties depend on fiber type, fiber surface treatment and composite thermal history. Results are explained by a morphological model which includes both adsorptive and covalent interactions. 227. Structure-propertyrelatfonsbipsat the composite interphase L. T. Drzal (Air Force Wright Aeronautical Laboratories, AFWAUMLBM, WPAFB, OH 45433) and M. J. Rich and D. L. Hall (University of Dayton Research Institute, Dayton, OH 45469). Fiber finishes composed of matrix resins without curing agent are applied to graphite fibers after surface treatment and before composite fabrication. Besides preserving the reactivity of surface groups, insuring wetting and protecting the surface from handling damage, this “finish” creates a brittle interphase between the fiber and the matrix which not only increases interfacial shear strength but also changes the mode of failure from interfacial to matrix. 228. Klnetks of oxygen chemfsorptionon pitch fiber P. C. Pinoli, J. G. Moncur and D. G. McKinstry (Department of Materials Sciences, Lockheed Palo Alto Research Laboratory, Palo Alto, CA 94304). Desorption CO and CO2 spectra of progressively activated low fired pitch fiber indicate at least 4 bond sites within an Ed range of 230-320 kJ mole-‘. Progressive activation by air at 470°C was found to increase the total CO/CO2 desorption ratio from 6.1: 1 to 12.7: 1; an oxygen chemisorption rate of 8.37 x 1019 molecules O2 per gram carbon - minute was determined.
into consideration multiple modes of failure, by using a mixture of Weibull distributions. The probability density of the mixed distribution is directly fitted to experimental data by maximum likelihood techniques. This model leads to more accurate strength estimates at short gage lengths. 231. Strain induced stiffening in carbon fibers Charles P. Beetz, Jr. (Physics Department, General Motors Research Laboratories, Wawen, MI 48090). Strain dependence of piezoresistance and stress have been measured simultaneously for single Thronel-P fibers. The stress/strain curve shows a -5% increase in slope at -0.2-0.4% strain. In cyclic strain measurements, this stiffening is accompanied by an irreversible component in piezoresistance. These results are discussed in terms of an elastic unwrinkling model of fiber structure. 232. The measurement of stacking size and lattice dfstortion in carbon Rbres D. J. Johnson (Department of Textile Industries, The University, Leeds, LSZ 9JT, England). Optical transforms and computer simulations have been analysed to obtain realistic Scherrer parameters for use with diffraction line broadening methods for evaluating stacking size and lattice distortion in carbon fibers or other carbons. Comparison with the direct methods of lattice fringe measurement in TEM prints has been used as a check on the validity of these new parameters. 233. Electron spin resonance and the structure of carbon fibers Janice Breedon Jones and L. S. Singer (Union Carbide Corporation, Carbon Products Division, Parma Technical Center, P.O. Box 6116, Cleveland, OH 44101). Electron spin resonance measurements have been carried out on PAN- and mesophase pitch-derived carbon fibers heat treated to high temperature. By utilizing a novel computer program, the spectra have been analyzed in terms of the degree of preferred orientation and “single crystal” g-anisotropy and lineshape. Both electronic and structural information have been inferred from the results.
229. Wettabflity of finisbed carbon yams from wicktng rate measurements S. Chwastiak (Union Carbide Corporation, Carbon 234. Catalytic graphftfzationof carbon 6bers Products Division, Parma Technical Center, P.O. Box I. Mochida, I. Itoh, Y. Korai, H. Fujitsu and K. 6116, Cleveland, OH 44101). Commercial carbon yarns Takeshita (Research Institute of Industrial Science, contain finishes which complicate the evaluation of their Kyushu University 86, Fukuoka 812, Japan). Catalytic wettability. The wetting determinations of such yarns by graphitization of carbon fibers was studied using wicking rate measurements can be improved by chromium compound to obtain highly graphitic fibers modification of the way the data are analyzed. Results of maintaining its bulk shape. By impregnating the nitric wetting experiments on finished carbon yarns, obtained salt form THF solution, the highly graphitized fiber was by the modified analysis, will be presented. The relative derived. The graphitization mechanism was investigated merits of measuring wettability on yarn bundles or on by means of microscopic technique. single filaments will be discussed. 235. Microstructureof mesopbasecarbon fiber 230. Analysis of carbon Bbertensile strength distributions J. L. White, C. B. Ng, M. Buechler and E. J. Watts exhibiting multiple modes of failure (The Ivan A. Getting Laboratories, The Aerospace CorCharles P. Beetz, Jr. (Physics Department, General poration, P.O. Box 92957, Los Angeles, CA 9ooo9). The Motors Research Laboratories, Wawen, MI 48090). A outer layers of round random-structured filaments as statistical model of fiber has been developed which takes well as cracked radial-structured filaments show exten-
Abstracts sive wrinkling and corrugation. A disclination model seems to apply to the core of round filaments, the transitions from round to cracked structures imply disclination interactions along the length of the filament. 236. The textile prestretching of PAN-fibres as a controlling parameter for the mechanical properties of the resulting carbon-fibres E. Fitzer and Th. Muller (Inslitut furChemischeTechnik, Universitiit Karlsruhe, BRD). PAN-fibres, obtained from two different sources, having different polymer composition and textile stretch, were oxidized in air at 230°C for optimum time and subsequently carbonized. The influence of textile stretching on the necessary stabilization conditions and on the mechanical properties of the resulting carbon fibres are discussed. 237. The influenceof textile prestretchiugon the cyclization kinetics of PAN-fibres E. Fitzer and Th. Multer (Znstitut fiir Chemische Technik, Universitiit Karlsruhe, West Germany). The kinetics of cyclisation reactions occurring during stabilization of PAN-fibres in air and nitrogen were studied by DTA-experiments as stabilization reactions play an important role in the production of high performance carbon fibres from PAN. Prestretching was found to influence the kinetic data tremendously. The results will be discussed with regard to the adaptation of the oxidation treatment to the stretching ratio of various PANfibres. 23% An optical and scanning microscopy study of structure in PAN carbon fibres J. A. Griffiths and H. Marsh (Northern Carbon Research Laboratories, School of Chemistry, University of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7RU, England). Optical microscopy identifies three
concentric regions (skin, body and core) of optical anisotropy, in a PAN-based carbon fibre. These regions may result from the initial oxidation and carbonization of the fibre. High-resolution phase-contrast electron microscope fringe imaging identifies only two regions (skin and body). Etching in chromic acid combined with scanning electron microscopy differentiates between body and core regions in the fibres.
XI.STRUCTURE AND CHARAfXERIZATION
I51
240. Laser Raman spectra of carbon materials R. P. Vidano and D. B. Fischbach (Deparfment of Mining, Metallurgical and Ceramic Engineering, FB- 10, University of Washington, Seattle, WI 98195). To facili-
tate further assessment of the nature of the Raman activity and its usefulness for carbon materials characterization, the spectral characteristics (line position, width, relative intensity) have been surveyed and correlated with layer-structure development over a broad range obtained from a variety of material types, HTT and damaging treatments. A small red-shift of the primary disorder band and its overtone with increasing optical excitation wavelength has been observed.
241. Signal-averagedRaman spectra of coals H. A. Nye, V. Lorprayoon and B. C. Cornilsen (Department of Chemistry and Chemical Engineering, Michigan Technological University, Houghton, MZ49931). Raman spectral differences can be related to
the properties of coals of various ranks and sources. Precision spectra (high S/N ratio) have been collected via signal averaging using a computer-interfaced instrument. The instrumentation will be described and variation of spectral parameters discussed in light of coal variables.
242. Investigation of oxygen surface complexes on carbon by XPS F. G. Fischer and A. R. Feichtinger (Graphite Technical Centre, LONZA AG, Sins, Switzerland). Surfaces of graphitic carbons are covered by various amounts of oxygen complexes. These complexes have been detected by XPS. 243. Routine determination of inorganics in carbon and graphite by wavelength dispersive XRF B. J. Lewis, J. R. McIver and L. A. Joo’ (Great Lakes Research Corporation, Elizabethton, TN). This paper describes a new procedure for the direct quantitative elemental analysis of inorganic material in carbons and graphites using a pressed pellet technique. This is accomplished quickly and accurately without the necessary time required to ash and fuse the sample. The method also provides for sample preparation and the mathematical correction models necessary to correct for interelemental effects.
OF CARBON
AND THEIR GRAPIDTIZATION
239. Carbon films: comparative study of structure microtexture and optical constants J. N. Rouzaud, A. Oberlin and M. Oberlin (Laboratoire
244. Radial distributionanalysis of a glassy carbon of very large surface area P. D’Antonio and J. H. Konnert (Laboratory for the
Marcel Mathieu, ER 131 du CNRS, EUR Sciences 45046, Orleans, Cedex, France). Carbon films, prepared under
Structure of Matter, Naval Research Laboratory, Washington, DC20375). An activated carbon of very
vacuum by condensating carbon vapor were heat-treated from room temperature to 2650°C. Indexes of refraction and absorption were computed from the measurements of reflectance, transmittance and thickness. Structural and microtextural changes were compared first to Raman spectra, then to the optical constants. The relationships between these data are discussed.
large active surface area (35OOm*/gm)prepared from petroleum coke has been examined with X-ray diffraction techniques. Simultaneous analysis of the high and low angle scattering has yielded a radial distribution function that provides information concerning the degree of stacking, the preferred growth directions, and the curvature of the hexagonal layers of carbon atoms.
CAR Vol. 20. No. Z-E
Abstracts
226. Fiber-polymerinteractions in graphite fiber/polymer composites Y. S. Ko, W. Forsman and T. Dziemianowicz (Department of Chemical Engineering, University of Pennsylvania, Philadelphia, PA 19104). Dynamic mechanical measurements and short beam shear tests have been used to characterize an Epon 828/MPDA epoxy resin and its composites with types A and HM carbon fibers. T, of the unfilled resin is sensitive to both epoxy stoichiometry and curing schedule. Composite properties depend on fiber type, fiber surface treatment and composite thermal history. Results are explained by a morphological model which includes both adsorptive and covalent interactions. 227. Structure-propertyrelatfonsbipsat the composite interphase L. T. Drzal (Air Force Wright Aeronautical Laboratories, AFWAUMLBM, WPAFB, OH 45433) and M. J. Rich and D. L. Hall (University of Dayton Research Institute, Dayton, OH 45469). Fiber finishes composed of matrix resins without curing agent are applied to graphite fibers after surface treatment and before composite fabrication. Besides preserving the reactivity of surface groups, insuring wetting and protecting the surface from handling damage, this “finish” creates a brittle interphase between the fiber and the matrix which not only increases interfacial shear strength but also changes the mode of failure from interfacial to matrix. 228. Klnetks of oxygen chemfsorptionon pitch fiber P. C. Pinoli, J. G. Moncur and D. G. McKinstry (Department of Materials Sciences, Lockheed Palo Alto Research Laboratory, Palo Alto, CA 94304). Desorption CO and CO2 spectra of progressively activated low fired pitch fiber indicate at least 4 bond sites within an Ed range of 230-320 kJ mole-‘. Progressive activation by air at 470°C was found to increase the total CO/CO2 desorption ratio from 6.1: 1 to 12.7: 1; an oxygen chemisorption rate of 8.37 x 1019 molecules O2 per gram carbon - minute was determined.
into consideration multiple modes of failure, by using a mixture of Weibull distributions. The probability density of the mixed distribution is directly fitted to experimental data by maximum likelihood techniques. This model leads to more accurate strength estimates at short gage lengths. 231. Strain induced stiffening in carbon fibers Charles P. Beetz, Jr. (Physics Department, General Motors Research Laboratories, Wawen, MI 48090). Strain dependence of piezoresistance and stress have been measured simultaneously for single Thronel-P fibers. The stress/strain curve shows a -5% increase in slope at -0.2-0.4% strain. In cyclic strain measurements, this stiffening is accompanied by an irreversible component in piezoresistance. These results are discussed in terms of an elastic unwrinkling model of fiber structure. 232. The measurement of stacking size and lattice dfstortion in carbon Rbres D. J. Johnson (Department of Textile Industries, The University, Leeds, LSZ 9JT, England). Optical transforms and computer simulations have been analysed to obtain realistic Scherrer parameters for use with diffraction line broadening methods for evaluating stacking size and lattice distortion in carbon fibers or other carbons. Comparison with the direct methods of lattice fringe measurement in TEM prints has been used as a check on the validity of these new parameters. 233. Electron spin resonance and the structure of carbon fibers Janice Breedon Jones and L. S. Singer (Union Carbide Corporation, Carbon Products Division, Parma Technical Center, P.O. Box 6116, Cleveland, OH 44101). Electron spin resonance measurements have been carried out on PAN- and mesophase pitch-derived carbon fibers heat treated to high temperature. By utilizing a novel computer program, the spectra have been analyzed in terms of the degree of preferred orientation and “single crystal” g-anisotropy and lineshape. Both electronic and structural information have been inferred from the results.
229. Wettabflity of finisbed carbon yams from wicktng rate measurements S. Chwastiak (Union Carbide Corporation, Carbon 234. Catalytic graphftfzationof carbon 6bers Products Division, Parma Technical Center, P.O. Box I. Mochida, I. Itoh, Y. Korai, H. Fujitsu and K. 6116, Cleveland, OH 44101). Commercial carbon yarns Takeshita (Research Institute of Industrial Science, contain finishes which complicate the evaluation of their Kyushu University 86, Fukuoka 812, Japan). Catalytic wettability. The wetting determinations of such yarns by graphitization of carbon fibers was studied using wicking rate measurements can be improved by chromium compound to obtain highly graphitic fibers modification of the way the data are analyzed. Results of maintaining its bulk shape. By impregnating the nitric wetting experiments on finished carbon yarns, obtained salt form THF solution, the highly graphitized fiber was by the modified analysis, will be presented. The relative derived. The graphitization mechanism was investigated merits of measuring wettability on yarn bundles or on by means of microscopic technique. single filaments will be discussed. 235. Microstructureof mesopbasecarbon fiber 230. Analysis of carbon Bbertensile strength distributions J. L. White, C. B. Ng, M. Buechler and E. J. Watts exhibiting multiple modes of failure (The Ivan A. Getting Laboratories, The Aerospace CorCharles P. Beetz, Jr. (Physics Department, General poration, P.O. Box 92957, Los Angeles, CA 9ooo9). The Motors Research Laboratories, Wawen, MI 48090). A outer layers of round random-structured filaments as statistical model of fiber has been developed which takes well as cracked radial-structured filaments show exten-
Abstracts sive wrinkling and corrugation. A disclination model seems to apply to the core of round filaments, the transitions from round to cracked structures imply disclination interactions along the length of the filament. 236. The textile prestretching of PAN-fibres as a controlling parameter for the mechanical properties of the resulting carbon-fibres E. Fitzer and Th. Muller (Inslitut furChemischeTechnik, Universitiit Karlsruhe, BRD). PAN-fibres, obtained from two different sources, having different polymer composition and textile stretch, were oxidized in air at 230°C for optimum time and subsequently carbonized. The influence of textile stretching on the necessary stabilization conditions and on the mechanical properties of the resulting carbon fibres are discussed. 237. The influenceof textile prestretchiugon the cyclization kinetics of PAN-fibres E. Fitzer and Th. Multer (Znstitut fiir Chemische Technik, Universitiit Karlsruhe, West Germany). The kinetics of cyclisation reactions occurring during stabilization of PAN-fibres in air and nitrogen were studied by DTA-experiments as stabilization reactions play an important role in the production of high performance carbon fibres from PAN. Prestretching was found to influence the kinetic data tremendously. The results will be discussed with regard to the adaptation of the oxidation treatment to the stretching ratio of various PANfibres. 23% An optical and scanning microscopy study of structure in PAN carbon fibres J. A. Griffiths and H. Marsh (Northern Carbon Research Laboratories, School of Chemistry, University of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7RU, England). Optical microscopy identifies three
concentric regions (skin, body and core) of optical anisotropy, in a PAN-based carbon fibre. These regions may result from the initial oxidation and carbonization of the fibre. High-resolution phase-contrast electron microscope fringe imaging identifies only two regions (skin and body). Etching in chromic acid combined with scanning electron microscopy differentiates between body and core regions in the fibres.
XI.STRUCTURE AND CHARAfXERIZATION
I51
240. Laser Raman spectra of carbon materials R. P. Vidano and D. B. Fischbach (Deparfment of Mining, Metallurgical and Ceramic Engineering, FB- 10, University of Washington, Seattle, WI 98195). To facili-
tate further assessment of the nature of the Raman activity and its usefulness for carbon materials characterization, the spectral characteristics (line position, width, relative intensity) have been surveyed and correlated with layer-structure development over a broad range obtained from a variety of material types, HTT and damaging treatments. A small red-shift of the primary disorder band and its overtone with increasing optical excitation wavelength has been observed.
241. Signal-averagedRaman spectra of coals H. A. Nye, V. Lorprayoon and B. C. Cornilsen (Department of Chemistry and Chemical Engineering, Michigan Technological University, Houghton, MZ49931). Raman spectral differences can be related to
the properties of coals of various ranks and sources. Precision spectra (high S/N ratio) have been collected via signal averaging using a computer-interfaced instrument. The instrumentation will be described and variation of spectral parameters discussed in light of coal variables.
242. Investigation of oxygen surface complexes on carbon by XPS F. G. Fischer and A. R. Feichtinger (Graphite Technical Centre, LONZA AG, Sins, Switzerland). Surfaces of graphitic carbons are covered by various amounts of oxygen complexes. These complexes have been detected by XPS. 243. Routine determination of inorganics in carbon and graphite by wavelength dispersive XRF B. J. Lewis, J. R. McIver and L. A. Joo’ (Great Lakes Research Corporation, Elizabethton, TN). This paper describes a new procedure for the direct quantitative elemental analysis of inorganic material in carbons and graphites using a pressed pellet technique. This is accomplished quickly and accurately without the necessary time required to ash and fuse the sample. The method also provides for sample preparation and the mathematical correction models necessary to correct for interelemental effects.
OF CARBON
AND THEIR GRAPIDTIZATION
239. Carbon films: comparative study of structure microtexture and optical constants J. N. Rouzaud, A. Oberlin and M. Oberlin (Laboratoire
244. Radial distributionanalysis of a glassy carbon of very large surface area P. D’Antonio and J. H. Konnert (Laboratory for the
Marcel Mathieu, ER 131 du CNRS, EUR Sciences 45046, Orleans, Cedex, France). Carbon films, prepared under
Structure of Matter, Naval Research Laboratory, Washington, DC20375). An activated carbon of very
vacuum by condensating carbon vapor were heat-treated from room temperature to 2650°C. Indexes of refraction and absorption were computed from the measurements of reflectance, transmittance and thickness. Structural and microtextural changes were compared first to Raman spectra, then to the optical constants. The relationships between these data are discussed.
large active surface area (35OOm*/gm)prepared from petroleum coke has been examined with X-ray diffraction techniques. Simultaneous analysis of the high and low angle scattering has yielded a radial distribution function that provides information concerning the degree of stacking, the preferred growth directions, and the curvature of the hexagonal layers of carbon atoms.
CAR Vol. 20. No. Z-E