The influence of washing of rice straw lignin isolation on polyurethane synthesis for coating in biomedical application

This study examined the effectiveness of different washing methods in improving the quality and functionality of rice straw lignin for its application in the synthesis of polyurethane as a coating material for biomedical pulp. The findings demonstrated that lignin subjected to triple washing (LW3) displayed the highest level of purity, as evidenced by elevated values of ph-OH and total phenolic content. LW3 exhibited the lowest syringyl/guaiacyl ratio, however, it had the highest mean molecular weight. Moreover, the LW3 was employed as a precursor for the production of polyurethane. Kidney trays coated with polyurethane demonstrated prolonged resistance to hot and cold water for over 4 h. This coating effectively adhered to the fibers of the tray and sealed the pores, resulting in enhanced water resistance. This study offers valuable insights into the advancement of sustainable biobased materials for the purpose of utilizing agricultural byproducts in the synthesis of polymers for various high-value applications. • The triple-washing treatment yields lignin with a purity of 80.73 %. • The triple-washed lignin suggests the presence of highly reactive lignin. • The urethane has been successfully formed after the reaction of lignin with TDI. • Lignin-based polyurethane enhances the water resistance of biomedical pulp for up to 4 h.