NONLINEAR RHEOLOGICAL PROPERTIES OF SUSPENSIONS OF BRILLIANT CARMINE 6B IN POLYBUTADIENE

Non-linear viscoelastic properties of suspensions of brilliant carmine 6B in polybutadiene were investigated. The pigment particles of brill iant carmine 6B have a scaly shape and form a denser network structure in disperse medium and show complicated rheological properties depend ing on flow history. In this study suspensions of carmine 6B in polybu tadiene having different molecular weight were used as sample suspensi ons. Dynamic viscoelastic properties under various flow histories and stress overshoot measurements were mainly investigated and we discusse d about the relations between the rheological properties and network s tructure formed by carmine 6B pigments. The following are concluded. T he anisotropic shape carmine 6B pigments in lower viscosity disperse m edium tends to stack together which results in rupturing the network s tructure and this phenomenon is accelerated with applying moderate amp litude of oscillatory shear. The peculiar non-linear viscoelastic beha vior in suspension of carmine 6B can be explained by the competition b etween formation and breaking down of the network structure of floccul ated particles, (C) 1997 Elsevier Science S.A.