Characterising latex particles and fractal aggregates using image analysis |
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Authors: | S Tang C M McFarlane G C Paul C R Thomas |
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Institution: | (1) Centre for Bioprocess Engineering School of Chemical Engineering University of Birmingham Birmingham B15 2TT, UK e-mail: s.tang@bham.ac.uk, GB |
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Abstract: | The fractal nature of latex particles and their aggregates was characterised by image analysis in terms of fractal dimensions.
The one- and two-dimensional fractal dimensions, D
1 and D
2, were estimated for polystyrene latex aggregates formed by flocculation in citric acid/phosphate buffer solutions. The dimensional
analysis method was used, which is based on power law correlations between aggregate perimeter, projected area and maximum
length. These aggregate characteristics were measured by image analysis. A two-slopes method using cumulative size distributions
of aggregate length and solid volume has been developed to determine the three-dimensional fractal dimension (D
3) for the latex aggregates. The fractal dimensions D
1, D
2 and D
3 measured for single latex particles in distilled water agreed well with D
1 = 1, D
2 = 2 and D
3 = 3 expected for Euclidean spherical objects. For the aggregates, the fractal dimension D
2 of about 1.67 ± 0.04 (±standard deviation) was comparable to the fractal dimension D
3 of approximately 1.72 ± 0.13 (±standard deviation), taking the standard deviations into account. The measured three-dimensional
fractal dimension for latex aggregates is within the fractal dimension range 1.6–2.2 expected for aggregates formed through
a cluster-cluster mechanism, and is close to the D
3 value of about 1.8 indicated for cluster formation via diffusion-limited colloidal aggregation.
Received: 28 September 1998 Accepted: 29 October 1998 |
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Keywords: | Latex particles Aggregates Fractal dimensions Image analysis |
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