Conformational behaviour of poly(2,6-dimethyl-1,4-phenylene oxide) in solution - I: Intrinsic viscosity as a function of temperature

Intrinsic viscosities [η] of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) solutions have been measured as a function of temperature between 60 and 25°C. The solvents were toluene and trichloroethene. In both solvents, the [η]-T curve exhibited a point of inflection in the range 45-35°. This phenomenon is explained as a conformational transition, which is possibly involved in the nucleation process of the solution crystallization of PPO. Assuming constancy of the coil expansion factor αη and the solvent draining over the whole temperature interval, a slight increase of characteristic parameter Cα, with decreasing temperature has been calculated.