Formation and behavior of carbonaceous mesophase in petroleum pitch
The phase behavior of conventional liquid crystals with nonmesomorphs was studied and compared to mixtures of mesophase pitches with aromatic molecules. Experimental phase diagrams of p-polyphenyls, p-azoxyanisol and various aromatic molecules were used to estimate the virtual mesophase-isotropic transition temperatures of the latter. The mesophase-isotropic transition in mesophase pitch, hidden by reactions, decreases the solubility of nonmesomorphs as would be predicted by the phase behavior of conventional liquid crystals. From vapor osmometry, gel permeation chromatography and elemental analysis, models of Ashland 240 and a solvent extracted Ashland 240 mesophase pitch were developed. The 3 to 5-ringed aromatic species contained within Ashland 240 are the polymerized subunits forming the branched molecules of the solvent extracted mesophase pitch. The effects of air blowing, sparging and heat soaking on the nature and constitution of mesophase formed from Ashland 240 pitch also were examined and compared to the solvent extracted pitch. The nature and consequently the behavior of the mesophase formed was found to be process dependent. The utility of mesophase pitches is derived largely from the local molecular orientation. Experimentally observed changes in local order as a function of temperature and time at temperature were attributed to the hidden mesophase-isotropic transition temperature and the reactions which mask this transition. The orientation, relaxation, and stabilization of locally ordered subunits into an overall preferred orientation was examined by melt spinning mesophase pitches into fibers.
- Research Organization:
- Rensselaer Polytechnic Inst., Troy, NY (USA)
- OSTI ID:
- 6108955
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
Similar Records
Process for isolating mesophase pitch
Pitch fractionation. Technical report
Related Subjects
PITCHES
PHASE STUDIES
LIQUID CRYSTALS
MOLECULAR MODELS
PETROLEUM PRODUCTS
TEMPERATURE EFFECTS
TIME DEPENDENCE
CRYSTALS
FLUIDS
LIQUIDS
MATHEMATICAL MODELS
ORGANIC COMPOUNDS
OTHER ORGANIC COMPOUNDS
023000* - Petroleum- Properties & Composition
020500 - Petroleum- Products & By-Products