Compact Fiber Optic Dynamic Light Scattering System

Area of Science:

• Materials Science
• Chemical Engineering
• Optics

Background:

• Fiber optic dynamic light scattering (FODLS) is an emerging technique for particle sizing.
• Its application in concentrated dispersions is crucial for process industries.
• Online particle size measurement is a key industrial requirement.

Purpose of the Study:

• To investigate the capabilities of FODLS for particle size analysis in concentrated dispersions.
• To evaluate the influence of particle size, volume fraction, and signal-to-noise ratio on FODLS measurements.
• To determine whether FODLS probes self-diffusion or collective diffusion based on particle size.

Main Methods:

• Utilized two different laser light sources for experiments.
• Studied monodisperse polystyrene latex dispersions with varying particle sizes and volume fractions.
• Analyzed apparent diffusion coefficients as a function of experimental parameters.

Main Results:

• Apparent diffusion coefficients were dependent on particle size, volume fraction, and signal-to-noise ratios.
• FODLS demonstrated the ability to probe collective diffusion for smaller particles and self-diffusion for larger particles.
• In polydisperse concentrated dispersions, FODLS probed both self and collective diffusion.

Conclusions:

• The apparent diffusion coefficient obtained from FODLS in concentrated dispersions is a relative quantity.
• FODLS is a promising technique for online particle size measurement in industrial processes.
• Understanding the probed diffusion mode (self vs. collective) is essential for accurate interpretation of FODLS data.