Characterization of bisphenol A-based epoxy resins by HPLC, GPC, GPC-MALLS, VPO, viscometry, and end group analysis: On the identification of 2,3-dihydroxypropyl-containing compounds, determination of molar mass distribution, and branching

Reversed-phase high performance liquid chromatography (HPLC), conventional gel permeation chromatography (GPC), and gel permeation chromatography coupled with a multiangle laser light scattering photometer (GPC–MALLS) were used for the analysis of epoxy resins based on bisphenol A. Compounds containing 2,3-dihydroxypropyl group were identified in HPLC chromatograms by means of the derivatization of sample by acetone. The presence of branched molecules was proved by GPC–MALLS using a molar mass versus root mean square (RMS) radius plot or molar mass versus elution volume plot. The molar mass distribution determined by HPLC was compared with that obtained by GPC–MALLS. Molar mass averages measured by means of GPC, GPC–MALLS, vapor pressure osmometry (VPO), and end group analysis (EG) were compared and the differences of results obtained by particular methods were discussed. An appropriate GPC calibration was found on the basis of literature data and the comparison of molar mass averages measured by GPC, VPO, and GPC–MALLS. The refractive index increment of epoxy resins was determined. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2432–2438, 1999