RHEOLOGY OF SUSPENSIONS - THE FLOW BEHAVIOR OF COATING COLORS

In this work, we discuss the role of interactions in coating colours o n the low rate and linear viscoelastic behaviour (viscosity, viscoelas ticity and yield stress). show the different physical contributions to these values. A simple model is proposed to describe the steady-state viscosity of coating colours, accounting for yield stress and structu re. During the coating process, a coating colour experiences a wide ra nge of deformation rates, the largest in the nip of a roll or under a blade. However, at high deformation rates, the contact times are very short and, in these conditions, the total deformation remains very sma ll. For simulating such conditions, we have measured the transient pro perties in stress growth experiments and have used an orifice rheomete r that allows us to obtain very high deformation rates at small deform ation in a flow that is mostly elongational. We present different tran sient rheological tests at low and high deformation rates.