A MODIFIED UBBELOHDE VISCOMETER WITH IMPROVED DILUTION CHARACTERISTICS

A simple modification of the standard Ubbelohde dilution viscometer is proposed. It consists of replacing the commercially supplied dilution reservoir with a siphon tube leading to a much larger custom-built storage container. Typically, the usual twofold dilution capability of commercial pieces can be increased to as much as ten- or twelvefold without loss of accuracy. Examples are presented illustrating how this modification simplifies and accelerates data acquisition for the routine measurement of polymer intrinsic viscosity and in addition allows for the use of very small quantities of polymer. The former point is illustrated through routine measurement of the intrinsic viscosity of a thermoplastic polyelectrolyte polymer containing 2-hydroxyethyl methacrylate and methacrylic acid, and the latter through an analysis of changes in intrinsic viscosity accompanying thermally induced chain scission in "Phenoxy" resin (Union Carbide, poly(bis-phenol-A, 2-hydroxypropylether)). © 1990.