Shear effects on expanded graphite under uniaxial pressure: An in situ small angle neutron scattering study

Félix Balima (1) , Sylvie Le Floch (1) , Alfonso San-Miguel (1) , Peter Lindner (2) , Annie Brulet (3) , L. Duclaux (4) , Vittoria Pischedda (1)

1 ILM - Institut Lumière Matière [Villeurbanne]
2 ILL - Institut Laue-Langevin
3 LLB - UMR 12 - Laboratoire Léon Brillouin
4 LCME - Laboratoire de Chimie Moléculaire et Environnement

In a previous work [1] we elucidated the in situ evolution of the porosity of out-of-plane com- pressed flexible graphite under uniaxial pressure up to 1000 bar using small-angle neutron scattering (SANS) technique. In order to understand the influence of shear effect on the properties of flexible graphite we study, in the present paper, the in situ behaviour of in-plane compressed flexible graphite under a uniaxial pressure. The sample had a pleated layered structure in which anisotropic SANS patterns revealed a distribution of differently oriented ellipsoid pores. Uniaxial compression generates important shear effects in this kind of sample.We have determined the evolution of the system fractal dimension, pore size distribu- tion and apparent specific surface area with applied pressure which together allow us to describe the meso and macro pore structure evolution. Under pressure, the irreversible col- lapse and splitting of larger pores into smaller size ones which is characteristic of out-of- plane uniaxial compression [1], is accompanied, in the presence of shear stress compo- nents, by an in-plane slipping mechanism giving rise to cracks and consequently to inter- face formation.

Domaines: Chimie analytique; Chimie inorganique; Ingénierie de l'environnement

Félix Balima, Sylvie Le Floch, Alfonso San-Miguel, Peter Lindner, Annie Brulet, et al.. Shear effects on expanded graphite under uniaxial pressure: An in situ small angle neutron scattering study. Carbon, 2014, 74, pp.54-62. ⟨10.1016/j.carbon.2014.03.002⟩. ⟨hal-01217509⟩