Pore space extraction and characterization of sack paper using μ-CT

Area of Science:

• Materials Science
• Physics
• Engineering

Background:

• Paper, particularly sack kraft paper, is vital for packaging due to its porosity and strength.
• Accurate quantification of paper porosity and pore network properties is challenging.
• X-ray microcomputed tomography (μ-CT) offers a non-destructive method for analyzing paper microstructure.

Purpose of the Study:

• To investigate if μ-CT imaging and statistical analysis of microstructure can reliably distinguish between different sack kraft papers.
• To explore pore structure extraction and analysis for larger sample areas using μ-CT, despite potential resolution limitations.

Main Methods:

• Attenuation X-ray microcomputed tomography (μ-CT) was used to capture the 3D pore space of two sack kraft paper samples.
• Image segmentation employed indicator kriging, a two-step local method, to accurately assign voxels as pore or fiber.
• Statistical comparison of microstructures used descriptors like thickness, porosity, accessible pore fractions, and mean geodesic tortuosity.

Main Results:

• μ-CT successfully extracted the 3D pore space of paper samples with a resolution of 1.5 μm over areas of 5 mm².
• Indicator kriging effectively resolved ambiguities in voxel identification between paper fibers and pores.
• Quantitative comparison of porosity and thickness necessitates a standardized definition of paper surfaces.

Conclusions:

• Statistical pore space analysis using μ-CT scans reliably reveals structural differences between paper samples.
• Distinguishing between paper samples requires the use of multiple pore network descriptors.
• The method provides a robust approach for characterizing paper's internal structure and differentiating material variations.