Abstract:

Eight standard polyacrylic acid(PAA) samples with different molecular mass were obtained via an isothermal precipitation grading method by using dioxane as solvent and petroleum ether as precipitator. Their peak molecular mass and molecular mass distributions were determined from an asymptotic calibration method. The results showed that the average relative errors for Mη are about 7% and 9% compared with those obtained using viscometry end-group titration, respectively. When these standard samples were used for determining the molecular mass as well as their distributions for actual PAA samples, the average relative error is less than 10%, which is superior to that using polyethylene glycol(PEG) as standard samples(about 30%). The PAA standard samples in gel permeation chromatography(GPC) might be extended to other anionic polyelectrolytes with similar structure for the same purpose.

Key words: PAA, molecular weight standard sample, GPC, precipitation grading, asymptotic method calibration