X-ray Computed Tomography for Characterization of Expanded Polystyrene (EPS) Foam

Area of Science:

• Materials Science
• Acoustics
• Polymer Science

Background:

• Expanded polystyrene (EPS) foam is vital for thermal and acoustic insulation in construction.
• Its X-ray transparency hinders 3D pore structure characterization, limiting understanding of its acoustic properties.

Purpose of the Study:

• To develop a method for visualizing and quantifying the 3D pore network of EPS foam.
• To investigate the relationship between EPS foam microstructure and its sound absorption characteristics.

Main Methods:

• Combined high-resolution X-ray tomography (micro-CT) with saturation techniques using CsCl-brine as an X-ray contrast agent.
• Analyzed 3D micro-CT data to determine pore and bead size distributions and assess the representative elementary volume.
• Utilized the Johnson-Champoux-Allard (JCA) model and simulated sound absorption curves based on 3D structural data.

Main Results:

• Successfully visualized the 3D pore network of EPS foam by distinguishing beads from pores using CsCl-brine.
• Determined the pore and bead size distribution and established a representative elementary volume for acoustic property calculations.
• Simulated sound absorption curves, revealing that increased bead size significantly enhances sound absorption at specific frequencies.

Conclusions:

• The combined micro-CT and saturation method effectively reveals the complex pore structure of EPS foam.
• Bead size is a critical microstructural parameter influencing the sound absorption performance of EPS foam.
• This research provides a pathway to optimize EPS foam for enhanced acoustic insulation applications.