Rheology of polyisobutylene. I. Theory and experimental procedures

A formulation is given of the response of a body manifesting linear viscoelastic behavior in shear to arbitrary simple shear stress history. A description is given of procedures for the measurement of the retarded elasticity function and of the viscosity by means of experiments under constant shear stress and following removal of stress. The non‐Newtonian flow of polymers is considered. Existing information on the viscosity of polyisobutylene as a function of temperature and molecular weight is reviewed. The applicability of the kinetic theory of rubberlike elasticity to a system of linear molecules is discussed. The use is described of the concentric cylinder rotational viscometer for the measurement of non‐Newtonian flow and of linear viscoelastic behavior.