A general correlation of foam shear modulus G₀ and yield stress τ_y with the interfacial elastic modulus of foaming solutions in shear and dilation E_∞ was found for surfactant, block-copolymer, protein, food, and particle-stabilized foams.

Microorganisms produce a great variety of secondary metabolites that feature surface active and bioactive properties. Those possessing an amphiphilc molecular structure are also termed biosurfactant and are of great interest due to their often unique properties. Rouxiella sp. DSM 100043 is a gram negative enterobacter isolated from peat-bog soil and described as a new biosurfactant producing species in this study. Rouxiella sp. produces glycolipids, biosurfactants with a carbohydrate moiety in its structure. This study characterizes the composition of glycolipids with different hydrophobicities that have been produced during cultivation in a bioreactor and been extracted and purified from separated foam. Using two dimensional nuclear magnetic resonance spectroscopy, the hydrophilic moieties are elucidated as glucose with various acylation sites and as talose within the most polar glycolipids. The presence of 3′ hydroxy lauroleic acid as well as myristic and myristoleic acid has been detected.

Glycolipids are a class of biodegradable surfactants less harmful to the environment than petrochemically derived surfactants. Here we discuss interfacial properties, foam stability, characterized in terms of transient foam height, gas volume fraction and bubble diameter as well as texture of seven enzymatically synthesized surfactants for the first time. Glycolipids consisting of different head groups, namely glucose, sorbitol, glucuronic acid and sorbose, combined with different C10 acyl chains, namely decanoate, dec-9-enoate and 4-methyl-nonanoate are compared. Equilibrium interfacial tension values vary between 24.3 and 29.6 mN/m, critical micelle concentration varies between 0.7 and 3.0 mM. In both cases highest values were found for the surfactants with unsaturated or branched tail groups. Interfacial elasticity and viscosity, however, were significantly reduced in these cases. Head and tail group both affect foam stability. Foams from glycolipids with sorbose and glucuronic acid derived head groups showed higher stability than those from surfactants with glucose head group, sorbitol provided lowest foam stability. We attribute this to different head group hydration also showing up in the time to reach equilibrium interfacial adsorption. Unsaturated tail groups reduced whereas branching enhanced foam stability compared to the systems with linear, saturated tail. Moreover, the tail group strongly influences foam texture. Glycolipids with unsaturated tail groups produced foams quickly collapsing even at smallest shear loads, whereas the branched tail group yielded a higher modulus than the linear tails. Normalized shear moduli for the systems with different head groups varied in a narrow range, with the highest value found for decylglucuronate.

Size and shape of dispersed objects defines properties of suspensions, emulsions, and foams, such as stability, texture, and flow. Accordingly, a rational product design requires reliable size distribution analysis. This is particularly challenging in dense foams. An endoscopic setup was optimized for bubble imaging minimizing light reflections, uneven illumination, and foam distortion. A software tool was developed detecting large quantities of foam bubbles at dispersed phase fractions up to 93 % from images with spatially varying contrast within minutes based on the template matching algorithm. Reliability of the method is also illustrated for a bimodal glass bead mixture, anisotropic nanocrystals, and emulsion droplets during freezing.

Driven by the increasing demand for high‐performance batteries, this study addresses the need for efficient and scalable mixing processes in battery manufacturing, focusing on continuous mixing in twin‐screw extruders. While extruders can operate at different production rates, process limitations require a scale‐up to larger extruder sizes to further increase production capacity. This work compares the quality of anode slurries produced under equivalent process conditions on four different scales of twin‐screw extruders. It was shown that the transfer from laboratory to pilot and production scale, while maintaining consistent product quality, i.e. dispersion of the conductive additive, is feasible. Flow simulations were used to quantify the material strain in each process setup, thereby facilitating the identification of relevant scale‐up criteria and even allowing for process transfer to similar but not geometrically equivalent screw geometries. Additionally, the influences of different process parameters such as screw speed and mass flow rate on the dispersion quality were quantified and compared between scales. In short, processing with a specific feed load smaller than 0.01 was shown to provide better dispersion and electrode quality across scales.