Resistance of Kapok Fibers ( <i>Ceiba pentandra</i> ) to Biotic and Abiotic Degradation: Evaluation by SEM, FTIR, Py-GC/MS, and Colorimetry

Kapok fibers (Ceiba pentandra) are considered sustainable materials, but their durability under stress is poorly understood. This study examined their resistance to abiotic (UV radiation, heat) and biotic (Aspergillus niger) degradation. Fibers were exposed to 100 h of UV irradiation, 100 h of heating at 104°C, and 14 days of fungal colonization, individually and combined. Changes were analyzed with scanning electron microscopy (SEM), colorimetry, Fourier-transform infrared spectroscopy (FTIR), and pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS). Hemicelluloses and amorphous polysaccharides were the most vulnerable components. UV irradiation caused yellowing, surface cracking, and oxidative lignin modification. Heat led to moderate browning, related to sugar degradation and lignin condensation. Fungal exposure caused the most severe effects: fiber collapse, darkening, enzymatic polysaccharide depolymerization, and lignin oxidation. Sequential stresses showed synergy: UV-pretreated fibers degraded faster under heat or fungal attack, accelerating polysaccharide loss and lignin disruption. Overall, kapok fibers are highly susceptible to combined abiotic and biotic stress, which compromises structural integrity and long-term durability. Protective measures against UV radiation and fungal colonization are crucial for reliable industrial and environmental applications.