LIQUID-CHROMATOGRAPHY TECHNIQUES FOR CHARACTERIZING POLY(VINYL ALCOHOL)

Poly(vinyl alcohol) (PVOH) samples may contain several heterogeneities requiring the development of chromatographic techniques for character ization. Size exclusion separations have been carried out using a numb er of aqueous eluents, incorporating electrolyte, or electrolyte/organ ic modifier, or surfactant. The most favourable molecular size separat ion was obtained using 0.25% w/v sodium lauryl sulfate as eluent. Reas onable values for molecular weights of PVOH samples have been determin ed. Compositional distributions in copolymer systems can be assessed u sing high-performance liquid chromatography employing a reversed-phase separation mechanism. For poly(vinyl alcohol), gradient elution with water/tetrahydrofuran (THF) with a wide pore polystyrene-based packing produced separations dependent on degree of hydrolysis and sequence l ength distribution. The elution results were verified with a column pa cked with non-porous beads. Partially hydrolysed PVOH samples appeared to have a broad distribution of composition.