RHEOLOGICAL AND BOUNDARY CHARACTERIZATION OF UNVULCANIZED RUBBERS AND THEIR COMPOUNDS.

摘要

An experimental investigation of rheological and boundary.;is reported in this dissertation. Stress relaxation, shear viscosity,;elongational viscosity, and frictional force under controlled.;pressurized conditions are examined for various elastomers and.;condition characterization of unvulcanized rubber and compounds.;their compounds.;Almost all of the experiments were carried out by a series of new instruments which were designed and built during work on the dissertation. These instruments are sandwich-style devices for stress relaxation, shear flow, and creep experiments; a rotating clamp elongational viscometer; and a friction tester in which a pressurized cylinder of rubber is pushed past a solid steel surface.;Commercial rubber SBR-1500 approaches zero shear viscosity.;((eta) (DBLTURN) 8 x 10('8) Pa(.)s) at a shear rate ((gamma)(' )=(' )1 x 10('-7) sec('-1)). Highly filled compounds (SBR-1500 with carbon black (N326), volume percent (phi) = 0.3) exhibit very high viscosities ((eta) = 1.5 x 10('10) Pa(.)s at (gamma)(' )=(' )8 x 10('-7) sec('-1)) and yield stress ((sigma)(,s) = 1.3 x 10('4) Pa).;The elongational viscosities of SBR-1500 and its compounds do not achieve steady state. The maximum values of the transient elongational viscosities of SBR-1500 and compounds ((phi) = 0.3) are (chi) = 7.5 x 10('7) Pa(.)s at E = 2.49 x 10('-3) sec('-1) and (chi) = 1.2 x 10('8) Pa(.)s at E = 2.49 x 10('-3) sec('-1) respectively.;Comparisons of experimental data with theoretical predictions of rheological models are discussed.;Flow in the closed cylinder of the friction tester was investigated as a function of pressure and linear velocity at 100(DEGREES)C. Discontinuities or inflections are found in the relation of the friction force and pressure.