COMPOSITIONAL CHARACTERIZATION OF AES BLENDS BY SIZE-EXCLUSION AND PRECIPITATION-REDISSOLUTION LIQUID-CHROMATOGRAPHY

Chemical composition characterization of blends formed by styrene-acry lonitrile (SAN), ethylene-propylenediene (EPDM) and EPDM-g-SAN copolym er molecules has been performed with size-exclusion chromatography wit h DRI and UV detectors. With proper detector calibration reliable aver age composition results were obtained, whereas it has been found that the composition distributions calculated from the chromatogram fractio ns are affected by large experimental errors. The blend components wer e successfully separated with precipitation-redissolution liquid chrom atography, and an evaporative light scattering detector was found suit able for eliminating baseline drifts in the chromatograms, due to the eluent gradients which had to be employed. The application of evaporat ive detectors for quantitative measurements, however, appears question able.