Full Bio‐Based Polyvinyl Alcohol Film With Excellent Flame Retardancy and Improved UV ‐Shielding Property Based on Phytic Acid and Tannic Acid

ABSTRACT Developing full bio‐based polyvinyl alcohol (PVA) film with exceptional flame retardancy and improved UV‐shielding property remains a major challenge. Here, bio‐based phytic acid (PA) and tannic acid (TA) were incorporated into PVA by a simple solution blending method. Due to the inherent flame retardant characteristics and synergistic flame retardant role of PA and TA, the resulting PVA composite film presented outstanding flame retardant performance. Specifically, the PVA/PA/TA film exhibited excellent self‐extinguishing behavior, achieving UL‐94 VTM‐0 level and a high limiting oxygen index of 45.3%. Compared with pristine PVA film, the peak heat release rate and total heat release showed reductions of 57% and 64%, respectively. Furthermore, contributed to the abundant hydrogen bond sites in the molecular structures of PA and TA, multiple hydrogen bond networks were constructed. The elongation at break of PVA/PA/TA film improved to 250.2% from 153.0% for PVA film, increasing by 63.5%. Additionally, due to the UV absorbing functional groups existing in PA and TA, the PVA/PA/TA film presented enhanced UV‐shielding property. This work paves the way for fabricating advanced PVA films for packaging and electronics by a simple, sustainable and effective approach.