LAUSR

A promising route is established to produce a liquefied cellulose‐based epoxy resin via phenol‐catalyzed liquefaction, glyoxal cross‐linking, and epoxidation. To simultaneously enhance flame retardancy and mechanical strength, attapulgite (ATP) was organically engineered with a phosphorus–silicon coupling agent (KH560–DOPO) to create a hybrid filler (AKD). The incorporation of 6 wt% AKD enabled the composite to achieve a UL‐94 V‐0 rating and a high limiting oxygen index (33.1%), while tensile strength and elongation at break increased by 36.7% and 24.1%, respectively. The analysis confirmed the successful liquefaction of cellulose and the covalent grafting of phosphorus and silicon onto ATP. The AKD/LCP composite material has a synergistic flame retardant mechanism of condensed phase and gas phase. The synergistic P–Si–C framework effectively promoted char formation and reinforced the polymer network. This work demonstrates a scalable route to stabilize renewable cellulose into high‐performance epoxy resins, combining bio‐based chemistry with advanced flame‐retardant nanotechnology and providing new ideas for the development of fire‐resistant polymeric materials.