Three-dimensional fibre composites

Abstract

A study was made of rheological properties of PVC plastisols modified with oligoester acrylates (OEA) over a wide range of shear velocities. An extremal relation was derived between viscosity and the index of non-Newtonian flow of plastisols and the concentration of OEA. A correlation was established between the viscosity of OEA and the viscosity of plastisol. It was shown that replacement of part of the molecular weight plasticizer of dioctyl phthalate with less viscous linear OEA results in the inversion of flow curves of the initial and modified plastisols. An increase in the viscosity of modified plastisol, measured at low shear velocities is due to the associative nature of the oligomer. On increasing shear velocity or reducing the concentration of OEA, the associates break down the and viscosity of the system is determined by the viscosity of the liquid phase itself. An assumption was put forward that an increase in the stability of the rheological behaviour of plastisols during prolonged retention is due to possible chemical conversions of OEA.