Stability analysis of tannin-based foams using multiple light-scattering measurements

Abstract

Liquid foams were prepared by whipping aqueous solutions based on natural polyphenols, surfactant and crosslinker. The destabilisation mechanisms of such thick, opaque and viscous liquid foams were investigated for the first time with a light-scattering detection method using an optical analyser. The technique allowed separating processes such as drainage, coalescence and coarsening, and sedimentation, so that each of them could be investigated independently as a function of whipping time, surfactant amount, and temperature. The corresponding average bubble diameters could also be determined as a function of time. It was shown that this kind of optical analysis is quite relevant for optimising formulations and foaming conditions with the aim of recovering rigid foams after polymerisation, having a given homogeneous structure that might be useful for various applications such as thermal insulation or acoustic absorption.