Dual‐Component Phytic Acid/Gallic Acid System for Enhancing Flame Retardancy and Multifunctional Packaging Performance of Polyvinyl Alcohol Films

Although polyvinyl alcohol (PVA) exhibits excellent film‐forming ability, transparency, and biodegradability, its inherent flammability limits its applications. In this study, phytic acid (PA) and gallic acid (GA) were employed as a synergistic flame‐retardant system to prepare flame‐retardant PVA composite films via solution blending. The flame‐retardant properties and underlying mechanisms of the films were systematically investigated and characterized via limiting oxygen index (LOI), UL‐94 vertical burning tests, thermogravimetric analysis (TG), cone calorimetry (FTT), scanning electron microscopy (SEM), Raman spectroscopy, and related techniques. At a PA:GA mass ratio of 3:1, the composite film achieved a UL‐94 VTM‐0 rating at a total loading as low as 10 wt%. At the highest loading tested (20 wt%), the LOI reached 47%, the peak heat release rate decreased by 81.2% relative to neat PVA, and the char residue at 600°C increased to 28.8%. Mechanistically, PA and GA enable a spatially differentiated mechanism involving “condensed‐phase char formation” and “gas‐phase flame inhibition,” as well as a temporally coordinated sequence of “char formation followed by flame suppression,” thereby enhancing the flame retardancy of the composite films. The composite film also exhibited a transmittance of 94.9% at 550 nm, an elongation at break of 590.207%, and the PA/GA system showed antibacterial activity against Escherichia coli .