A Rheological Interpretation of the Hottenroth Index Method for Viscose

Abstract

Some rheological properties of viscose during titration with various salt solutions, especially ammonium chloride, have been studied by employing a new automatic tester. The principle of the tester is to record automatically the change in viscosity of the viscose sample during titration with salt solution; the change in torque required for stirring the sample at constant velocity is converted into the change in electrical potential by means of a linear variable differential transformer device. From the experi mental results it is concluded that the conventional Hottenroth index method for de termining the degree of ripeness of viscose does not always determine a volume of 10% NH₄Cl solution by which coagulation of the viscose sample just sets in. On the other hand, it has been found that viscose with ammonium chloride solution added manifests a thixotropic nature, and a new rheological interpretation has been put on the Hottenroth index method; it measures a volume of 10% NH ₄Cl solution by which a viscose sample becomes notably thixotropic.