Rheology of PVC Plastisol: III. Analyses of Dilatancy and Fracture

✍ Scribed by N. Nakajima; E.R. Harrell

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 65 KB
• Volume: 241
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.2001.7733

✦ Synopsis

In the preceding paper of this series (N. Nakajima and E. R. Harrell, J. Colloid Interface Sci. 238, 116 (2001)), the pseudo-plastic behavior of PVC plastisol was analyzed to explain that the shear rate dependence of viscosity was a result of the formation of immobilized layer. The idea of the immobilized layer was based on the works of R. L. Hoffman (Trans. Soc. Rheol. 16, 155 (1972); J. Colloid Interface Sci. 46, 491 (1974)), who examined the mechanisms of fracture of PVC plastisols at high shear rates. In our calculation a particular form of the viscosity-particle concentration relationship by C. W. Johnston and C. H. Brower was used (SPE J. 26, 31 (1970)). In this study the above work was extended to the region of dilatancy. The increase of viscosity with the increase of shear rate was explained by the dilatation of the immobilized layer. When the dilatation approached its critical limit, the immobilized layer fractured, creating clusters of particles. The degree of clustering was estimated in terms of the amount of trapped plasticizer within the cluster. The amount of the trapped plasticizer decreased as the clusters were broken up when shear rate was increased.