Preparation And Fire Hazard Research Of Halogen-Free Flame Retardant Polylactide

Polylactide(PLA), which is developed recently, is a new kind of environmental-friendly biodegradable material, and its raw material is renewable natural resources, besides, it is low energy consumption and has good biocompatibility, mechanical properties and processability, therefore, it’s one of the most promising candidates for petroleum-based materials, and has a widely application prospect. It has been used in many fields, such as biomedical fields, textile industry, packaging materials, electronic and electrical devices, automotive parts and so on. Unfortunately, just like other polymer materials, PLA is flammable and heavily dripped in combustion, its LOI value is only20, the big fire hazard restricts potential applications of PLA. In order to expand its application range, the flame retardant treatment to PLA is necessary.In order to prepare flame retardant PLA, this thesis used epoxy resins as a modifier of ammonium polyphosphate to improve its hygroscopicity and compatibility with PLA, prepared a halogen-free flame retardants, MAPP, containing acid source, char forming agent and blowing agent simultaneously, its structure was characterized by FT-IR and SEM, the influence of EP content in MAPP on the hygroscopicity of APP is researched; PLA/MAPP composites were prepared by melting blending method, and characterized by LOI, tensile properties test and TGA test, the influence of the composition of this flame retardant on the flame retardant performance, mechanical properties and thermal decomposition behavior of PLA was studied; the effect of flame retardant on the fire hazard of flame retardant PLA was analyzed by cone calorimeter, and the visual analysis of the fire hazard of flame retardant PLA was studied by FDS.The main results of this thesis can be summarized as follows:1. The results of FT-IR and SEM show that a interaction has happened between EP and APP, the EP modified APP is prepared successfully; the result of hygroscopicity test shows that EP improves the hygroscopicity of APP effectively.2. The results of LOI test show that flame retardant MAPP can improve the flame retardant properties of PLA, when the mass ratio of APP to EP is1.2:1, the flame retardant effect is the best; The results of tensile properties test show that the addition of flame retardants decreased the mechanical properties of PLA. when the mass ratio of APP to EP is1.2:1, the flame retardant PLA composites has the best mechanical properties; the results of TGA test show that the addition of flame retardant into PLA lowered the initial degradation temperature of PLA, the thermal stability of PLA is declined, but the degradation rate of PLA is slowed down.3. PLA is flame retarded by MAPP4, which has the best combination property, the cone calorimeter test of neat PLA and flame retardant PLA is carried on. The results show that the addition of flame retardant into PLA lowered the heat release rate and total smoke production of PLA, but the smoke toxicity of PLA is slightly increased.4. The results of FDS simulation show that, in the same boundary conditions, when neat PLA is combusts, the environmental temperature is higher than that of flame retardant PLA, that means the addition of flame retardant into PLA decreased the heat release of PLA, reduced the fire hazard of the heat release of PLA.