be the case for homocoagulation. On the other hand, since most fibrillar biopolymers have a zero or slightly negative charge density, electrostatic repulsion and thus the energy barrier preventing aggregation will be small. Furthermore, due to the formation and interactions of helices comprising the rigid biopolymers, their thickness and thus the van der Waals forces of the fibril segments may be significantly larger than for a corresponding segment of a single chain. Because freshwater fibrils may be much longer than the diameter of the colloids (Table 7.1), they can serve as rigid (or semirigid) long distance bridges between the colloids. Furthermore, attached, compact colloids may serve as the binding center for polymers, leading to the formation of loose aggregate networks that extend to very large dimensions.

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