Fibers clay deposition

Figure 1.7 Deposition of clay on fibers, induced by PEO. In the absence of PEO or for clay pretreated with PEO for 30 min or longer, no deposition takes place. Because PEO does not adsorb on fibers, this is an example of asymmetric polymer bridging, in which PEO first from Ref [31]). adsorbs on clay, prior to clay deposition on fibers.

Alince, B., Petlicki, J. and van de Ven, T.G.M. (1991) Kinetics of colloidal particle deposition on pulp fibers. I. Deposition of clay on fibers of opposite charge. Colloids cj Surfaces, A, 59, 265-277. 

There also exist complex temporary destabilization processes of colloidal solutions. For instance almost all electroneutral polymers can cause a destabilization of an originally asymmetric systems. One example is a mixture of a clay, fibers and noncharged PEO (polyethyleoxide [62]), where both type of colloids are negatively charged. If PEO is added to only clay it adsorbs, while if PEO is added to only fibers it does not adsorb at all. In a study by van de Ven et al. [63], it was shown that in the mixture clay and PEO deposited on the fibers for several hours and the complexes initially... 

Sodium montmorillonite quickly and irreversibly deposits onto cellulose at extremely low clay concentrations [61-63], It exhibits some fiber lubrication properties. 

Clay constitutes the most abundant and ubiquitous component of the main types of marine sediments deposited from outer shelf to deep sea environments. The clay minerals are conventionally comprised of the <2 pm fraction, are sheet- or fiber-shaped, and adsorb various proportions of water. This determines a high buoyancy and the ability for clay to be widely dispersed by marine currents, despite its propensity for forming aggregates and floes. Clay minerals in the marine environments are dominated by illite, smectite, and kaolinite, three families whose chemical composition and crystalline status are highly variable. The marine clay associations may include various amounts and types of other species, namely chlorite and random mixed layers, but also ver-miculite, palygorskite, sepiolite, talc, pyrophyllite, etc. The clay mineralogy of marine sediments is therefore very diverse according to depositional environments, from both qualitative and quantitative points of view. 

Defects in paper sheet. The biofilm or thin slime deposit can further increase in size as it entraps the wood fibers, carbonates, clays and other particles normally used in the papermaking process. 

An additional interesting observation is that the deposition is transient and the particles leave the fibers with time. This is due to a flattening of PEO, which increases the electrostatic repulsion between fibers and day particles. Adding PEO to day prior to adding it to fibers, and allowing time for the PEO to flatten onto the clay, leads to no deposition (Figure 1.7). 

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