New analytical methods for epoxy resins, 1 : Liquid chromatography at the critical point of adsorption and MALDI-TOF mass spectrometry

The analysis of bisphenol A based epoxy resins by size exclusion chromatography, liquid chromatography at the critical point of adsorption and MALDI-TOF mass spectrometry with respect to molar mass, functionality, and branching is described. For obtaining proper molar masses, size exclusion chromatography must be calibrated by a combined calibration curve based on polystyrene and epoxy resin oligomers. Liquid chromatography at the critical point of adsorption yields quantitative data on different functionality fractions, including fully epoxydized, glycidyl-diol and bisdiol oligomers. The different functionality fractions can be efficiently identified by MALDI-TOF mass spectrometry. In addition, these measurements yield information on the number of branching points per oligomer molecule.