Thixotropy Hysteresis and Structure Formation in Elastomeric Suspensions

Resumo

A method for identifying normal and anomalous thixotropy hysteresis in elastomeric composites containing powdered reinforcement materials of different nature is proposed, and the explanation of existence of the two forms of hysteresis is provided. We assume that large superstructural elements—clusters consisting of a number of reinforcement particles, of colloidal particles, and of the matrix—may arise in such systems. The formation of clusters in the system gives rise to normal hysteresis, and hysteresis is anomalous in the absence of clusters. Instant thixotropy is observed when the rates of formation and disintegration of clusters are equal. The hysteresis changes its character in the inversion regions, which are the regions of critical shear stress that divides the stress–shear velocity field into low- and high-velocity domains.