Lecithin/graphite modified kapok fibers for functional xerogel composites

Kapok fibers (KFs) exhibit a distinctive hollow tubular structure and hydrophobic surface, positioning them as intriguing materials with a leading role in developing new materials for various applications. In this study, KFs from Ceiba speciosa trees underwent modification with soy lecithin (SL) and graphite (G) particles. The wax on KFs primarily comprised hydrophobic compounds, including bis(2-ethylhexyl) phthalate, N – N -dimethyldodecanamide and 1-chloro-dodecane. These compounds interacted favorably with the alkyl chains of SL, exposing the SL charge groups to the medium, as confirmed by X-ray photoelectron spectroscopy (XPS) and wettability increase. Incorporating SL and G particles to the KFs improved their thermal stability and charring capability. KFs modified with SL and G (at 13 wt% or 16 wt%) were added to aqueous solutions of hydroxypropyl methylcellulose (HPMC) at 30 g L −1 , forming homogeneous dispersions that were molded and oven-dried to create xerogel composites. Regardless of the G content, all xerogels exhibited compressive elastic modulus of 23 ± 1 kPa, maximum strain of 60% strain at 5.6 ± kPa stress, and after unloading, the xerogels recovered 77% of their original height. Their porosity amounted to 68 ± 3%. The xerogels showed a maximum sound absorption coefficient (SAC) of approximately 0.6 at 2 kHz, making them interesting sustainable materials for building and architecture. Surface resistivity and volume resistivity values amounted to 3.8 × 10 8 Ω/square and 8.84 × 10 8 Ω cm, respectively, indicating that the xerogel composites displayed antistatic properties and potential application as packing material.