Synthesis of oligomeric models of coal-derived materials for use with GPC calibration. Quarterly report, April-June 1983
A series of model oligomers were used to calibrate four high-pressure gel permeation columns. Three types of model compounds used in the experiment were commercially prepared polystyrene polymers, a series of oligo(aryl ethers) prepared and a series of oligo(aryl methylenes) both prepared at our laboratory. It was found that a nearly linear relationship exists between the logarithm of the molecular weight and the retention volumes using tetrahydrofuran solvent as long as the aryl groups in the oligomer were of the benzenoid type. Aryl oligomers containing more condensed ring systems such as naphthyl or phenanthryl moieties give too great a retention volume for their actual molecular weight. Tests with a few low-molecular-weight, hyroxyl-containing oligomers give too small a retention volume, indicating that hydrogen bonding with the solvent is occurring. Samples of relatively narrow molecular weight ranges of lignite-derived preasphaltenes and asphaltenes were also analyzed using the same system. In these experiments the samples were acetylated and their number-average molecular-weight values measured by vapor pressure osmometric means. In the range 300-2000 g/mole, these samples fit the same calibration plot as the polystyrene and aryl-ether oligomers. Those asphaltenes with a high degree of aromatic condensation, particularly at low molecular weight, behaved in a fashion analogous to our more condensed models, i.e. the retention volumes were too large. We plan to investigate this phenomenon further by preparing some vinylnaphthalene, vinylphenanthrene, and vinylpyrene oligomers as calibration standards in our future work.
- Research Organization:
- North Dakota Univ., Grand Forks (USA)
- DOE Contract Number:
- FG22-81PC40810
- OSTI ID:
- 5694878
- Report Number(s):
- DOE/PC/40810-6; ON: DE83014968
- Country of Publication:
- United States
- Language:
- English
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Evaluation of oligomeric models of coal asphaltenes and preasphaltenes as GPC calibration standards. [Gel permeation chromatography]
Synthesis of oligomeric models of coal derived materials for use with GPC calibration. Quarterly report, June 1984-September 1984
Related Subjects
400105* -- Separation Procedures
ASPHALTENES
ASPHALTS
BITUMENS
CALIBRATION
CHEMICAL PREPARATION
CHROMATOGRAPHY
ETHERS
GEL PERMEATION CHROMATOGRAPHY
MOLECULAR WEIGHT
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OTHER ORGANIC COMPOUNDS
POLYMERS
SEPARATION PROCESSES
STRUCTURAL MODELS
SYNTHESIS
TAR