X-ray scattering measurements of particle orientation in a sheared polymer/clay dispersion

Saswati Pujari (1) , Leah Dougherty (1) , Christophe Mobuchon (2) , Pierre Carreau (2) , Marie-Claude Heuzey (2) , Wesley R Burghardt (3)

1 Department of Chemical and Biological Engineering
2 Center for Applied Research on Polymers and Composites
3 Department of materials science and engineering

We report steady and transient measurements of particle orientation in a clay dispersion subjected to shear flow. An organically modified clay is dispersed in a Newtonian polymer matrix at a volume fraction of 0.02, using methods previously reported by Mobuchon et al. (Rheol Acta 46: 1045, 2007). In accord with prior studies, mechanical rheometry shows yield stress-like behavior in steady shear, while time dependent growth of modulus is observed following flow cessation. Measurements of flow-induced orientation in the flow-gradient plane of simple shear flow using small-angle and wide-angle X-ray scattering (SAXS and WAXS) are reported. Both SAXS and WAXS reveal increasing particle orientation as shear rate is increased. Partial relaxation of nanoparticle orientation upon flow cessation is well correlated with time-dependent changes in complex modulus. SAXS and WAXS data provide qualitatively similar results; however, some quantitative differences are attributed to differences in the length scales probed by these techniques.

Domaines: Mécanique [physics.med-ph]; Matériaux

Saswati Pujari, Leah Dougherty, Christophe Mobuchon, Pierre Carreau, Marie-Claude Heuzey, et al.. X-ray scattering measurements of particle orientation in a sheared polymer/clay dispersion. Rheologica Acta, 2010, 16 (7), ⟨10.1007/s00397-010-0492-3⟩. ⟨hal-01007437⟩