Removal of hydrophobic fouling layers

Hydrophobic semi-solid soiling layers are both widespread and problematic, as their hydrophobicity inhibits interactions between cleaning agents which are
readily soluble in aqueous solutions. An important example of these is the polymerised grease layers generated during the cooking of meats. The soils are
complex, as autoxidate polymerisation occurs alongside protein degradation. Understanding and quantifying the interaction of such soils with substrates
including metals, ceramics, glasses and polymers in the absence and presence of aqueous solutions is needed to develop quantitative models for removal.
The related field of removal of hydrophobic liquids is well developed, where the mechanisms include emulsification and roll-up, however the semi-solid
soiling layers are often viscoplastic, which limits the application of oily layer based approaches: minimum forces have to be exerted on these materials in
order to deform or detach them from a substrate. Detergents may soften the materials, or promote peeling, but hydraulic forces are needed to achieve this
removal. In this project I will develop and apply methods for visualising and quantifying the changes which accompany the removal of hydrophobic soft
solid layers. Specific objectives include (i) monitoring the ingress of agents which promote detachment of the layer, either by peeling or the formation of
blisters; (ii) relating the forces required to remove layers to the nature of the substrate, and the factors determining the timescale - are these controlled by
diffusion, pH, or other factors; (iii) determining the influence of layer composition, by controlled polymerisation of model soils. Strands (i) and (ii) will make
use of the techniques, particularly milimanipulation and fluid dynamic gauging, developed in the group in CEB.