# Shear modulus and yield stress of foams: contribution of interfacial elasticity

Völp, Annika R.; Willenbacher, Norbert

##### Abstract:
The link between interfacial elasticity of foaming solutions and the elasticity and yield stress of their aqueous foams is probed for a variety of surfactant, block-copolymer, protein, food, and particle-stabilized (Pickering) foams. We measured interfacial tension σ and interfacial elastic moduli of foaming solutions in dilation E$_{∞}$ as well as in shear Image G$_{i}$$^{'} at concentrations suitable for foaming and compared them to the shear modulus and yield stress of corresponding foams normalized by bubbles’ Sauter radius R_{32} and foams’ gas volume fraction. The interfacial shear modulus was only measurable for the foaming solutions including proteins or nanoparticles. For these systems the foam shear modulus scaled reasonably well with Image (σ+2G_{i}$$^{'}$/R$_{32}$). The interfacial dilational modulus was accessible for all investigated systems and the foam shear modulus as well as yield stress scaled with a generalized Laplace pressure (σ + 2E$_{∞}$)/R$_{32}$. But foams stabilized by nanoparticles or aggregated proteins exhibited even higher shear modulus and yield stress values not captured by the proposed scaling with the generalized Laplace pressure and also show an unexpectedly high dependence of these characteristics on the gas volume fraction. ... mehr

 Zugehörige Institution(en) am KIT Institut für Mechanische Verfahrenstechnik und Mechanik (MVM) Publikationstyp Zeitschriftenaufsatz Publikationsjahr 2021 Sprache Englisch Identifikator ISSN: 1744-683X, 1744-6848 KITopen-ID: 1000131878 Erschienen in Soft Matter Verlag Royal Society of Chemistry (RSC) Band 17 Heft 14 Seiten 3937-3944 Nachgewiesen in Scopus
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