Preparation and properties of water‐borne polyurethane‐sodium lignosulfonate/nano‐calcium carbonate composites

Abstract To improve the application range of waterborne polyurethane (WPU), in this study, nano calcium carbonate/sodium lignosulfonate (CaCO 3 /SL) composites were prepared using sodium lignosulfonate (SL) wet‐modified calcium carbonate nanoparticles. Then, a series of waterborne polyurethane (WPU) nanocomposites (WPU‐CaCO 3 /SL) were prepared by solution mixing. Zeta, FT‐IR, XRD, SEM, and TGA were used to characterize the structure and morphology of CaCO 3 /SL and WPU‐CaCO 3 /SL. By conducting an analysis on the impact of various dosages of CaCO 3 /SL composite on the performance of WPU, the findings revealed that the tensile strength of WPU‐CaCO 3 /SL nanocomposites, when composed with a 3 wt% CaCO 3 /SL dosage, exhibited a significant increase of 116% from 6.93 to 14.95 mPa. The water contact angle demonstrated a significant increase from 78.3° to 90.1°. Additionally, the maximum decomposition temperature showed a noticeable rise of approximately 7°C. The WPU exhibit enhanced heat resistance, water resistance and mechanical properties, as well as exceptional ultraviolet (UV) absorption capabilities. This study provides a reference for modifying polymers with inorganic fillers and improving the optical properties of polymeric materials. Highlights Successful modification of nano calcium carbonate using biopolymer SL. Modified CaCO 3 /SL can be uniformly dispersed in water. Improved thermal stability of WPU composites. WPU composites exhibit excellent mechanical properties and water resistance. Well‐dispersed CaCO 3 /SL improves ultraviolet radiation resistance of WPU composites.