Synergistic of UV resistant water-borne polyurethane sizing with metal chelation to enhance the interfacial properties of CF/PA6 composites

Currently, the challenge of achieving robust adhesion between carbon fibers and resins remains a focal point for exploring composites. This study introduces a waterborne polyurethane sizing agent employing natural biomass derived sodium alginate as the foundational material. The infusion of 4,4-dihydroxybenzophenone as a chain ext ender imparts the sizing agent with ultraviolet (UV) absorption capabilities. Additionally, chelation between Ca2+ and sodium alginate was harnessed to amplify the interfacial adhesion between the fibers and sizing agent, thereby fostering a more tenacious connection for the two entities and fortifying the fiber-resin interface. The ramifications of varying sizing agent concentrations on composite materials were methodically explored. Comparative analysis conducted against untreated CF composites discloses noteworthy enhancements in the interlaminar shear strength (ILSS) by 46 %, bending strength by 67 %, and interface shear strength (IFSS) by 57 % for CF-1.5 wt%/PA6 composites. Notably, even after enduring a week of xenon lamp aging, the mechanical integrity preserved at approximately 98 %. This inventive methodology presents a fresh avenue for bolstering the characteristics of CF composites.