Synergistic of anionic and nonionic monomers for high solid content bio-based waterborne polyurethane sizing agents

A high solid content bio-based waterborne polyurethane (WPU) was designed by combination of anionic and nonionic monomers, and serving as sizing agent for carbon fibers (CF). The electric double layer was formed by using bio-based tartaric acid (TA) and sodium lignosulfonate (SL) as donor of ionic groups and electrostatic repulsion was generated. Polyethylene glycol (PEG) was used to provide the hydrophilic segment of non-ionic monomer, which reduced the interfacial tension and improved the dispersion of emulsion. The synergistic effect of anionic and nonionic monomers promoted the stability of emulsion and the solid content of WPU sizing agent was arrived at 57%. The effect of sizing agent to the interfacial properties of carbon fiber reinforced nylon 6 (CF/PA6) composites were investigated. The flexural strength and interlaminar shear strength (ILSS) of the CF/PA6 composites exhibited the optimal performance at 1.5 wt% sizing concentration, revealing a considerably increase of 39.8% in ILSS and 38.5% in flexural strength as compared with untreated CF composites. This work contribute a fascinating method for further high solid content commercial production of environmentally-friendly WPU sizing agent.