A Comprehensive Review of Phytic Acid as a Bio-Based Flame Retardant for Polymer Composites

Abstract

Phytic acid, a naturally abundant and phosphorus-rich compound, is gaining attention as a bio-based flame retardant for polymer composites due to its environmental compatibility and intrinsic fire resistance. In recent years, research on phytic acid flame retardancy has been increasing annually, this paper comprehensively evaluates the structural characteristics and thermal properties of phytate based on a decade of relevant literature to understand its flame-retardant function. The flame-retardant mechanisms are discussed in detail, including condensed phase char formation, phosphorus-induced radical inhibition, and thermal stabilization. Various chemical modification approaches such as ionic coordination, phosphorylation, nitrogen functionalization, and Schiff base chemistry are examined for their ability to enhance flame retardancy and compatibility with matrices. Furthermore, the multifunctional characteristics of phytic acid, including antimicrobial activity, corrosion protection, and electrical conductivity, are highlighted as added value in composite design. Current challenges in material processing, formulation stability, and performance optimization are critically reviewed, along with perspectives on future research directions for the integration of phytic acid in high-performance material system.