Eco-Friendly Functionalization of Recycled Cotton-Pulp Wet-Laid Nonwovens: Influence on Water Repellency and Mechanical Performance

Functionalized wet-laid nonwovens were developed from recycled cotton fibres, including spinning process residues (SPRs) and cotton fabric scraps (CFSs), blended with refined bleached eucalyptus kraft pulp (BEKP), demonstrating the valorisation of textile waste into high-performance materials. A two-step surface functionalisation strategy was applied, combining spray deposition of a polyamide-amine wet-strength resin with padding using carnauba wax, polyurethane dispersion and their combination. SEM and ATR-FTIR analyses confirmed successful functionalization of the cellulosic nonwovens without affecting their structure. The surface modification induced a hydrophilic-to-hydrophobic transition, with SPR-based nonwovens showing higher contact angles (>130°), lower water uptake and slower liquid penetration. The applied functionalization strategies suppressed liquid strike-through (STT) across both nonwovens’ formulations. Mechanical performance was also enhanced. SPR-based nonwovens modified with the combined agents showed increases of 59% and 90% to 30/70% SPR/BEKP and 70/30% SPR/BEKP, respectively, while CFS-based nonwovens exhibited increases of 148% and 207% for the same formulations. Wet strength was noticeably improved, exceeding instrumental limits in SPR systems functionalized with polyurethane dispersion alone as well as with the combined agents. Therefore, this functionalization strategy effectively overcomes the intrinsic hydrophilicity and wet weakness of cellulosic nonwovens, enabling to be applied in packaging, household and other technical applications, while promoting the circular economy.