Spatial Modeling of Formation of Gel

Sammanfattning

Understanding and predicting colloidal interaction is important in a variety ofapplications. In this study, we investigate aggregation dynamics of colloidal silicaby generating simulated structures and comparing them to experimental datagathered through scanning transmission electroscopy (STEM). More specifically,diffusion-limited cluster aggregation (DLCA) and reaction-limited cluster aggregation(RLCA) models with different functions for the probability of particles stickingupon contact were used. Aside from using a constant sticking probability, the stickingprobability was allowed to depend on the masses of the colliding clusters andon the number of particles close to the collision. It was found that in comparisonto using a constant sticking probability, both the mass-dependent and neighbordependentsticking probability improved the goodness-of-fit of spatial summarystatistics when the simulated data were compared to the experimental data. Themodels were also compared based on fractal dimensions. Both in terms of goodnessof-fit for the summary statistics and the fractal dimension, the structures generatedwith a neighbor-dependent sticking probability were the most similar to the experimentaldata. This model was further analyzed by conducting global envelopetests based on the spatial summary statistics. The tests showed that although thesummary statistics are similar for the simulated and experimental structures, thereare also systematic deviations. Structures generated with the same model were alsocompared with the STEM data by simulating flow and diffusion. From this analysis,it was seen that the permeability and the geometry factor of the simulated andexperimental structures were relatively similar.