Abstract
The processing characteristics of agglomerates of silica aerogel particles (surface treated to possess either hydrophilic or hydrophobic nature) have been examined. Although these agglomerates were purported to be highly uniform in terms of internal structure, fluid infiltration studies performed via direct visualization revealed significant heterogeneities. Dispersion studies performed under both steady and time-varying flow conditions, revealed additional non-uniformities among the population of agglomerates. Despite these difficulties, discernable trends linked to the duration of time the agglomerates were allowed to soak in the processing medium prior to the application of the shear flows were discovered. Additional experiments, in which the agglomerates were presoaked with a different, low viscosity fluid prior to shearing, revealed that dispersion could be promoted through this processing strategy. The experimental approaches and analyses presented in this study should be of interest to particle technologists faced with understanding and characterizing dispersion phenomena when the agglomerates being dispersed exhibit significant variability in properties.
