Dynamics of Polymer Solutions. 3. An Instrument for Stress Relaxations on Dilute Solutions of Large Polymer Molecules

We have previously described an instrument with which it is possible to measure strain relaxations of dilute solutions of very large DNA molecules. Herein we describe substantial modifications of that instrument, so that we can additionally measure stress relaxations. Thus the combined instrument can measure the solution viscosity, the creep recovery, and the stress relaxation of a single sample of a dilute solution of large polymer molecules.