Pore structure of kapok fiber

Kapok is a natural fiber with an extremely high degree of hollowness. Numerous pores in its cell wall form the pathways for gas molecules. The delamination of the cell wall in scanning electron microscopy images and the hysteresis loop in nitrogen adsorption–desorption isotherms are interpreted to indicate that the kapok fiber has slit-shaped pores. Nitrogen adsorption method based on Brunauer–Emmett–Teller theory was used to analyze the mesopore. The specific surface area of kapok fiber is evaluated as 2.99 m²/g in the relative pressure range (0.05–0.35). The pore size of the fiber is distributed in 4–40 nm and mainly concentrated on 3–4 nm. The volume of the pores with diameters of 2–40 nm accounted for about 80% of the total pore volume, and those with diameters over 40 nm accounted for about 20%. By the V_a ~ α_s micropore evaluating method, it is found that the micropore volume of the fiber is about 7.0399×10⁻¹¹ ml/g.