Size Exclusion Chromatography of Meiamine-, Urea-, and Phenolformaldehyde Resins Using N, N-Dimethylformamide as Eluent

Abstract
Resins, hardly soluble in THF or chloroform, in the oligomer region were analyzed using DMF as solvent and a polystyrene column for oligomers. This column, 25 cm × 8 mm i.d., is the exclusive use of DMF and has the number of theoretical plates of 6000 per 25 cm. Polynuclear methylol melamines were resolved into individual polynuclear species and peaks from mono- to penta nuclear methylol melamines were identified. The thermal stability of methylol melamines can be monitored by this system. Molecular weight distributions of urea-formaldehyde resins and phenol-formaldehyde resole resins were observed. This PSt gel - DMF system will be useful for the process control or the quality control of these resins.