Fractal Morphology and Breakage of DLCA and RLCA Aggregates

Tang, Si; Preece, Jon A.; McFarlane, Caroline M.; Zhang, Zhibing

doi:10.1006/jcis.1999.6565

Cited by 79 publications

(56 citation statements)

References 18 publications

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“…Very few attempts have been reported in the literature 20,26,64 to keep track of the fractal dimension during the breakup process of an aggregate. Here, we have studied the evolution of the fractal dimension of the fragments under various conditions.…”

Section: Resultsmentioning

confidence: 99%

Universal Breakup of Colloidal Clusters in Simple Shear Flow

Harshe

Lattuada

2016

J. Phys. Chem. B

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ABSTRACT:We have studied the long-term dynamics of shear-induced breakage of individual colloidal clusters, covering a wide range of fractal dimensions, using Stokesian dynamics. We found that the time evolution of the normalized average size of the fragments generated by the breakup process could be scaled using a unique dimensionless time defined by multiplying the real time with the cluster breakage rate constant (τ = t·k B ). Clusters with different masses but the same fractal dimension exhibited almost identical breakage dynamics when exposed to equal overall hydrodynamic forces (ηγR g,0 2 ). The steady-state values of the average size, mass, and standard deviation of fragment mass distribution showed a universal scaling depending only on the overall hydrodynamic force, irrespective of the initial cluster properties. We also identified two asymptotic regimes for the evolution of the fractal dimension, ⟨d f ⟩, of fragments: open clusters (d f ≤ 2

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Section: Resultsmentioning

confidence: 99%

Universal Breakup of Colloidal Clusters in Simple Shear Flow

Harshe

Lattuada

2016

J. Phys. Chem. B

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“…In the former, particles have negligible repulsion forces and hence stick together on contact to form highly tenuous structures. However, in RLCA, a substantial repulsive force is maintained between particles, so the existence of a nearly zero aggregation probability is likely and particles may collide many times before sticking to each other [43]. A stability ratio less than unity indicates aggregation faster than that due to diffusion alone and aggregation is driven by electrostatic attraction superimposed on diffusion [40].…”

Section: Resultsmentioning

confidence: 99%

Effects of ageing conditions and block copolymer concentration on the stability and micellization of P123-Ti4+ sols prepared by the templating method

et al. 2010

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In the work reported here we studied, for the first time, the effects of ageing conditions (temperature and time) on the stability and micellization of two sets of sols with different P123 block copolymer (BC) concentrations by use of dynamic light scattering (DLS). Further, for a comparative study the aggregation/ clustering behavior of pure P123 in IPA solution was also examined by DLS, and 1 H NMR, and Raman spectroscopy at room temperature. Different ageing regimes applied to the samples prepared included: (i) in-situ ageing of the sols in the sealed capillary cell of the DLS system at room temperature for 0, 1, 2, 3, 4, 5, 6, and 19 h, (ii) ageing of the sols in a Teflon-lined sealed vessel at 50, 55, 60, and 65°C for 30 min, and (iii) isothermal ageing of the synthesized sols at 50°C for 1, 4, 8, and 14 days. On the basis of the results obtained it is shown that both ageing time and temperature have remarkable effects on the clustering and aggregation of unimer/ micelles formed in the sol system studied. Further, quantitative analysis of interparticle potential energy carried out for the prepared sol at low concentration confirmed that steric interactions play the major role among the other contributing sources of energy. This is mainly related to the presence of BC and the complex polymer structure formed by acetyl acetone (ACAC). Moreover, on the basis of the calculated stability ratio for this sol, we believe that reaction-limited cluster aggregation (RLCA) is possibly the major governing mechanism. Finally, kinetic and dynamic aspects of the micellar aggregates formed are also discussed in this paper.

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“…Studies have shown that fractal dimensions will approach a uniform asymptotic value under normal temperatures. For coagulation systems starting with monomers, the simulations (Moutain, Mulholland, & Baum, 1986;Kostoglou & Kongstandopoulos, 2001) and experiments (Tang, Preece, Mcfarlane, & Zhang, 2000) of continuum Brownian coagulation have shown that the aggregate fractal dimensions will reach an asymptotic value after a very short time. Kostoglou and Kongstandopoulos (2001) also came to the same conclusion by constructing a constitutive law for the fractal dimensions.…”

Section: Collision Kernels In the Continuum Regimementioning

confidence: 99%