▎ 摘　　要

NOVELTY - Preparing flame-retardant and toughened polylactic acid degradable composite decorative sheet comprises (1) stirring and mixing polyethylene glycol 1000 and polymerization inhibitor hydroquinone, and stopping the reaction at 40-50% esterification rate to obtain polyethylene glycol methacrylic acid monoester, (2) dissolving pyromellitic dianhydride, 4-dimethylaminopyridine and triethylamine in dichloromethane, (3) adding acid anhydride-modified polyethylene glycol methacrylate monoester into dimethyl sulfoxide solvent, (4) adding polyethylene glycol methacrylate monoester grafted graphene and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide into toluene solvent, and (5) soaking the wood fiber with ammonium polyphosphate and then cutting it into 7-10 mm fiber, adding polylactic acid, flame-retardant polyethylene glycol grafted graphene, 20-40 wt.% wood fiber and 1-3 wt.% crosslinking agent triallyl isocyanate to a twin-screw extruder for mixing. USE - The method is useful for preparing flame-retardant and toughened polylactic acid degradable composite decorative sheet. ADVANTAGE - The method: can inhibit the agglomeration of graphene, so that graphene has better dispersibility in the PLA matrix, can induce the phenomenon of shear craze in the polylactic acid matrix, which can strengthen and toughen the polylactic acid, due to the unique two-dimensional layered structure of graphene, can play a lamellar barrier effect in the polylactic acid matrix, plays a synergistic flame retardant role with the added flame retardant, grafts DOPO to the molecular chain of macromolecular polyethylene glycol, can overcome the shortcomings of small molecular flame retardants e.g. easy migration, unstable flame retardant effect, easy precipitation, large addition amount and great influence on polymer properties, has good flame retardant effect a polylactic acid decorative sheet with excellent comprehensive performance is obtained, which can meet the decorative use of polylactic acid in interiors and cars. DETAILED DESCRIPTION - Preparing flame-retardant and toughened polylactic acid degradable composite decorative sheet comprises (1) stirring and mixing polyethylene glycol 1000 and polymerization inhibitor hydroquinone, adding p-toluenesulfonic acid and water absorbing agent after heating up, then adding methacrylic acid, and stopping the reaction at 40-50% esterification rate to obtain polyethylene glycol methacrylic acid monoester, (2) dissolving pyromellitic dianhydride, 4-dimethylaminopyridine and triethylamine in dichloromethane, adding dropwise the dichloromethane solution of polyethylene glycol methacrylic acid monoester, performing ring-opening esterification reaction by stirring, after the reaction is completed, ether precipitating, filtering, washing, and vacuum drying to obtain acid anhydride-modified polyethylene glycol methacrylate monoester, (3) adding acid anhydride-modified polyethylene glycol methacrylate monoester into dimethyl sulfoxide solvent, stirring to dissolve, adding graphene, ultrasonically dispersing, heating up and stirring, adding aluminum chloride, under nitrogen atmosphere, carrying out FriedelCrafts reaction, until the reaction finishes, centrifugal separating, ultrasonically washing and vacuum drying to obtain polyethylene glycol methacrylate monoester grafted graphene, (4) adding polyethylene glycol methacrylate monoester grafted graphene and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide into toluene solvent, performing addition reaction by heating under reflux, after the reaction is completed, washing, steaming to remove the solvent, and vacuum drying to obtain flame-retardant polyethylene glycol grafted graphene, and (5) soaking the wood fiber with ammonium polyphosphate and then cutting it into 7-10 mm fiber, adding polylactic acid, flame-retardant polyethylene glycol grafted graphene, 20-40 wt.% wood fiber and 1-3 wt.% crosslinking agent triallyl isocyanate to a twin-screw extruder for mixing, extruding and pressing the master batch into a plate by a pressure forming machine to obtain flame-retardant and toughened polylactic acid degradable composite decorative sheet.