Dilute solution properties of polyamides in formic acid. Part II. The influence of ionic strength

✍ Scribed by Saunders, P. R.

• Publisher: John Wiley and Sons
• Year: 1962
• Weight: 457 KB
• Volume: 57
• Category: Article
• ISSN: 0022-3832
• DOI: 10.1002/pol.1962.1205716511

✦ Synopsis

Abstract

The light scattering, differential refractive index and intrinsic viscosity of nylon 66 dissolved in formic acid—water—potassium chloride solution have been studied. In contrast to work reported previously on formic acid—water—sodium formate solution, the degree of ionization of the polymer has not been reduced by common counterions; rather, the polyelectrolyte effects have been swamped by means of excess potassium chloride. The values of weight‐average molecular weight deduced from all the light scattering measurements in both systems were identical, which removes any doubts concerning the influence of selective absorption around the nylon molecules. A theta solvent was obtained from the potassium chloride solution, and the value of intrinsic viscosity measured in this solvent was identical with that predicted from the results in sodium formate solution. It was shown that the differential refractive index of nylon in dilute solution depends markedly on its degree of ionization.