Characterization of alkyd resins by size exclusion chromatography coupled with a multi-angle light scattering photometer

An on-line multi-angle light scattering detector (MALS) coupled with size exclusion chromatography (SEC) has been used for the determination of molar mass and size distribution of alkyd resins. Molar mass distribution of alkyd resins is usually determined by SEC using calibration by polystyrene standards (PS). Since the molecules of alkyd resins are significantly more compact than those of linear polystyrene the molar mass determined by conventional SEC is incorrect. The correct molar mass can be obtained using an on-line MALS detector that eliminates the column calibration. In addition, it allows sample differentiation in respect to their degree of branching. It was found that highly branched alkyd molecules have abnormal elution behavior.