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Title: Computer simulation of aggregation and gelation in colloidal suspensions
Author: Haw, Mark D.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1996
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Aggregation and gelation in colloidal suspensions are studied by computer simulation using the diffusion-limited cluster aggregation (DLCA) model. By studying the structure of the aggregating system in detail using computational methods analogous to scattering experiments, direct comparison is made with recent scattering experiments on fast colloidal aggregation. The simple DLCA model is shown to reproduce many features observed in experiments, including the appearance of an intense scattering peak at small angle or large length-scale, which is shown to correspond with a density modulation in the aggregating system at the inner-cluster length scale. The calculated scattering function is examined in detail by studying the structure of individual aggregates, the arrangement of aggregates in the system, and the effect of aggregate size-position correlations. The scaling properties of the scattering function are examined and simulation results compared to experiments. More direct investigation of scaling in the system is carried out by comparing the time evolution of various length scales. The DLCA model is extended to allow thermal restructuring of aggregates. In this 'reversible' model the typical morphology of the system varies from a near-fluid-like state with no long-lived large aggregates, through a system of near-compact clusters, to a near-space-filling gel made from locally compact filaments which are ramified at longer length scales. The irreversible DLCA model is thus the strong-bonding limit of this more general model of particle aggregation.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available