Supercritical fluid extraction: Preparing a superior mesophase precursor for carbon fibers. Final report
Supercritical fluid (SCF) extraction is being investigated for the production of mesophase pitch, the liquid-crystalline precursor for the manufacture of high-performance carbon fibers. The mesophase pitch is produced by fractionation of an isotropic petroleum pitch with supercritical toluene in a region of liquid-liquid equilibrium that exists at pressures above 40 bar. Dramatic improvements in the reliability of the apparatus have recently been made, and mesophase pitch can now be produced on a routine basis. An experimental program was conducted to explore the effects of temperature, solvent-to-pitch (S/P) ratio, and solvent solubility parameter on the properties of the mesophase pitch produced. Temperatures of 320 and 360 deg C, solubility parameters of 3.7 and 5.0 (cal/cc)(1/2), and S/P ratios of 2.5 and 3.5 were chosen to conform to a two-level, augmented factorial experiment. A linear model correlated the data to a high degree of certainty. Results indicate that the authors can adjust SCF operating conditions and tailor-make a mesophase pitch for a given end use. They have discovered a semitheoretical method for predicting a priori the softening point and yield of mesophase pitch for a given set of SCF operating conditions. The SCF extraction process can be represented on a pseudoternary phase diagram, and good estimates of product yields and softening points can be made from a limited experimental data measured at other conditions.
- Research Organization:
- Clemson Univ., SC (United States). Dept. of Chemical Engineering
- OSTI ID:
- 6861559
- Report Number(s):
- AD-A-284933/9/XAB; CNN: DAAL03-92-G-0194
- Country of Publication:
- United States
- Language:
- English
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Process for producing mesophase pitch
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Related Subjects
CARBON FIBERS
SYNTHESIS
PITCHES
SUPERCRITICAL GAS EXTRACTION
PETROLEUM PRODUCTS
PROGRESS REPORT
TOLUENE
ALKYLATED AROMATICS
AROMATICS
DOCUMENT TYPES
EXTRACTION
FIBERS
HYDROCARBONS
ORGANIC COMPOUNDS
OTHER ORGANIC COMPOUNDS
SEPARATION PROCESSES
SOLVENT EXTRACTION
360601* - Other Materials- Preparation & Manufacture