Characterization of Ethylene-Vinyl Acetate Copolymer by Eluent Gradient HPLC

The elution behaviors of ethylene-vinyl acetate copolymer (EVA) with different composition were characterized by gradient high-performance liquid chromatography. In this study, EVA samples having a narrow molecular-weight distribution containing vinyl acetate (VAc) from 18 wt% to 80 wt% were prepared by size exclusion chromatography for fractionation. EVA samples were eluted depending on the VAc content without depending on the molecular weight with a linear gradient from 100% acetonitrile to 100% chloroform. The relation between the VAc content in EVA and the composition of chloroform in the eluent at the time of EVA eluting indicated a good correlation, and the composition of chloroform in the eluent agreed with the critical adsorption point in the chloroform and acetonitrile eluent.