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228. Kinetics of oxygen chemisorption on pitch fiber
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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
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-