Polymer Relaxation Times from Birefringence Relaxation Measurements

Abstract

A theoretical description of the time dependence of induced birefringence in polymers, based on the ``pearl-necklace'' model, is presented, and relations between relaxation and frequency dependence methods are discussed. The relaxation theory is applied to the results of measurements of the longest relaxation time for the DNA from bacteriophage T2. The measured relaxation time, in the limit of infinite dilution, is τ1=0.45 sec. The molecular weight calculated from this value using the theoretical expression for a nondraining coil with excluded volume is in good agreement with the value of the molecular weight obtained from low-shear intrinsic viscosity measurements.