SOLUTION PROPERTIES AND LIGHT-SCATTERING MEASUREMENTS OF POLY(2,5-PYRIMIDINEDIYLTEREPHTHALAMIDE)

A series of chains of different molecular weight of the fully aromatic polyamide poly(2,5-pyrimidinediylterephthalamide)a) (PPYMT) in the so lvents 96 wt.-% sulfuric acid and methanesulfonic acid have been chara cterized by means of static and dynamic light scattering, dilute solut ion viscosimetry and measurements of the critical polymer volume fract ion for the onset of a nematic phase. The experimental results are in good agreement with a model of stiff worm-like chains for the solution conformation of PPYMT, and the persistence length is estimated to be ca, 150 angstrom (lower limit: 50-100 angstrom).