Supercritical fluid extraction: Preparing a superior mesophase precursor for carbon fibers. Final report

Technical Report · Mon Aug 01 04:00:00 EDT 1994

OSTI ID:6861559

Thies, M C

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

Related Subjects

36 MATERIALS SCIENCE
360601* -- Other Materials-- Preparation & Manufacture
ALKYLATED AROMATICS
AROMATICS
CARBON FIBERS
DOCUMENT TYPES
EXTRACTION
FIBERS
HYDROCARBONS
ORGANIC COMPOUNDS
OTHER ORGANIC COMPOUNDS
PETROLEUM PRODUCTS
PITCHES
PROGRESS REPORT
SEPARATION PROCESSES
SOLVENT EXTRACTION
SUPERCRITICAL GAS EXTRACTION
SYNTHESIS
TOLUENE