Surfactant-modified recycled fibers for enhanced dewatering and mechanical properties in sustainable packaging

Recycled fibers substantially lose their physical and mechanical properties with recycling time. This study explores the combined effects of pretreating old corrugated container (OCC) pulp, a type of recycled fiber, with surfactants and optimizing drying conditions to enhance dewatering efficiency and mechanical properties of packaging grades. Two surfactants- cetyltrimethylammonium bromide (CTAB), a cationic surfactant, and alcohol ethoxylate (NS), a non-ionic surfactant were employed for the recycled fiber modification. Packaging handsheets were prepared under various drying conditions, and their surface morphology and cross-sectional structure were characterized using scanning electron microscopy (SEM). The degree of chemical interactions in surfactant-fiber systems were evaluated using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Surfactant treatment effectively reduced surface tension to ∼47 mN/m, facilitating lower pulling forces, improved fiber dispersion and enhanced dewatering, with a drainage rate increase of 1.56-fold and reductions in hard-to-remove water (HRW) and water retention value (WRV) by ∼49 % and ∼13 %, respectively. SEM analysis revealed a more uniform handsheet morphology and the formation of fibril bridges, contributing to enhanced mechanical properties. Maximum values achieved included a tensile index of 54.1 Nm/g, ring crush test (RCT) strength of 12 Nm/g, and short-span compression test (STFI) strength of 31 Nm/g. In total, this novel strategy shows strong potential for enhancing recycled fiber performance in sustainable packaging applications.