A MARK-HOUWINK EQUATION FOR POLY(VINYL ALCOHOL) FROM SEC-VISCOMETRY

A new Mark-Houwink equation for fully hydrolyzed poly(vinyl alcohol) has been determined using aqueous size exclusion chromatography (SEC) with on-line, differential viscometry detection. The Mark-Houwink K and a constants have been measured at 35-degrees-C over a wide range of molecular weights in an aqueous solution of sodium nitrate, a commonly used mobile phase for SEC-molecular weight characterization of poly(vinyl alcohol). Absolute molecular weights determined using these Mark-Houwink values compare favorably among universal calibration, viscometry, and the Mark-Houwink (or intrinsic viscosity distribution) methods to those obtained from low-angle laser light scattering. The intrinsic viscosity distribution method is calibration independent and only requires a one time determination of the Mark-Houwink constants. This new method for characterizing molecular weight of an unknown poly(vinyl alcohol) is illustrated.