SIZE-EXCLUSION BEHAVIOR OF POLYMERS IN AMIDE SOLVENTS .2. MOLECULAR-WEIGHT DETERMINATION OF ACRYLONITRILE POLYMERS IN N,N-DIMETHYLFORMAMIDE

Size exclusion chromatography (SEC) procedure for the determination of molecular weight and molecular weight distribution of acrylonitrile polymers (PAN) is described. The Mark-Houwink-Sakurada parameters of PAN polymers in DMF and 0.01M LiBr-DMF at 60 degrees C were estimated. The values of a parameters obtained by us for PAN prepared both by persulfate-metabisulfite aqueous system (PAN), and azo-bis-isobutironitrile in DMF solution (PAN-A) were the same, while for PAN sample containing small amounts of sulfonated pendant groups (PAN-S) was higher. The addition of inorganic salt, such as LiBr, to DMF suppressed the abnormal SEC elution behavior observed in the solvent without the electrolyte although SEC of PAN-A showed almost the same results as in DMF with electrolyte. The universal calibration using monodisperse poly(ethylene oxide) standards as well as application of the Mark-Houwink-Sakurada parameters were satisfactory for the determination of the molecular weights.