A demethylated lignin improved PVA-based supramolecular plastic with tough, degradable, and water-resistant performances

Poly (vinyl alcohol) (PVA), as an excellent degradable plastic feedstock , is limited by its diminishing stability in wet environment, low strength , thermal instability and nonopaque properties. In response to these concerns, a PVA/demethylated lignin-based supramolecular plastic (DPVA-HA-Fe-5) was designed and produced from PVA, demethylated lignin (DL), humic acid (HA) and Fe 3+ ions via a simple casting method. As compared with pure PVA plastic, the tensile strength of DPVA-HA-Fe-5 were increased by 411 % to 410.61 MPa, and the breaking strain was increased by 149 % to 239.47 %. Notably, the hydrophobicity of DPVA-HA-Fe-5 was also significantly improved. Although in highly humid environment (stored in RH = 100 % for 10 days) or in alkaline organic solvent (stored in pyridine for 3 h), DPVA-HA-Fe-5 also showed excellent mechanical strengths of 302.9 and 222.99 MPa, respectively, which are equivalent or even superior to the most of commercial petroleum-based plastics. Moreover, the prepared plastics showed an outstanding UV resistance and shading performance, and about 98.3 % protection against ultraviolet radiation B rays and 90.7 % protection against visible light were obtained. In short, the introduction of lignin to improve the performance of PVA-based plastic is a feasible method, and it could facilitate the development of high-value utilization of lignin.