▎ 摘　　要

NOVELTY - Intumescent flame retardant comprises chitosan salt, and binary hybrid nanoparticle zeolitic imidazolate framework-8 doped graphene oxide (GO). The chitosan salt is prepared by reacting 2-carboxyethylphenylphosphinic acid with chitosan. USE - Used as intumescent flame retardant. ADVANTAGE - The polylactic acid material: has simple formula, and no halogen environment; obviously improves mechanical properties, and flame retardant properties of polylactic acid; obviously weakens droplets of flame-retardant polylactic acid material; forms continuous and dense carbon layer after combustion; and has heat insulating and oxygen barrier function. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) preparing intumescent flame retardant, comprising (i) dissolving 2-carboxyethylphenylphosphinic acid in water, heating at 60-70 degrees C in a water bath, stirring for completely dissolving to obtain 2 wt.% aqueous solution of 2-carboxyethylphenylphosphoric acid, adding chitosan to aqueous solution of 2-carboxyethylphenylphosphoric acid, stirring at 60-70 degrees C for 5-6 hours, cooling, precipitating, and drying to obtain chitosan salt, (ii) adding 2-methylimidazole, and zinc nitrate hexahydrate sequentially to methanol dispersion of graphene oxide to obtain ZIF-8 doped GO, and (iii) mixing chitosan salt, and ZIF-8 doped GO to obtain the product; (2) intumescent flame-retardant polylactic acid material comprising polylactic acid, and intumescent flame retardant having mass ratio of 95:5; and (3) preparing the intumescent flame-retardant polylactic acid material, comprising using solution blending method, adding chloroform solution of polylactic acid, and a chloroform dispersion of intumescent flame retardant in a mass ratio of 95:5, blending, and coating film to obtain the finished product.