Inorganic Phosphorus Flame Retardant Modified By Polystyrene Nanospheres And Its Application

With the development of society and living needs,polymer materials are widely used due to their mechanical,insulation and chemical resistance.However,most of these materials are flammable materials,which are easy to burn and produce a large amount of smoke and toxic gases,harming human health.In view of the flammability of polymer materials,adding flame retardant is the most effective improvement method.Traditional halogen flame retardants can release toxic hydrogen halide gas and harmful smoke when burning,and it is essential to develop environmentally friendly and non-toxic flame retardants.Phosphorus flame retardants are believed to be suitable candidate materials because of their high flame retardant efficiency,low smoke emission,and better environmental protection.Phosphorus flame retardants are the most widely used inorganic phosphorus flame retardants,such as red phosphorus（RP）and ammonium polyphosphate（APP）.However,RP and APP have the disadvantages of strong moisture absorption,poor compatibility with matrix,and low flame retardant efficiency.In view of these shortcomings of RP and APP,the coating modification is used to improve the flame retardancy of RP and APP in this paper,a systematical study is carried out on the effects of modified RP and modified APP on the flame retardancy,thermal stability and moisture absorption of polymer materials.This paper has carried out the following two aspects:（1）Preparation and properties of polystyrene nano microspheres coated RP（PSNS@RP）.Polystyrene nanospheres（PSNS）were synthesized by emulsion polymerization using styrene as raw material and coated on the surface of RP.It was found that the moisture absorption,ignition point,and phosphine gas release of PSNS@RP have been greatly improved compared with RP.The PSNS@RP flame retardant was added into nylon 66（PA66）to prepare PSNS@RP/PA66 flame retardant composite.Thermogravimetric analysis（TG）,oxygen index（LOI）,vertical combustion grade（UL-94）,cone calorimetry（CONE）and scanning electron microscope（SEM）were used to analyze the performance of PSNS@RP.Compared with PA66,the LOI of PSNS@RP/PA66 composites was increased from 24.8%to 34.2%.The flame retardant grade UL94 was increased from V-2 to V-0.The peak heat release rate（PHRR）was decreased from 1444.5 to 420.9k W m^-2,the total heat release rate（THR）was decreased from 145.8 to 94.2 MJ m^-2,and the total smoke release（TSP）was decreased by 35%.PSNS@RP/PA66composite has excellent flame retardancy and smoke suppression properties.（2）Silicon dioxide（SiO₂）nanoparticles and PSNS were synthesized by sol-gel and emulsion polymerization using tetraethyl orthosilicate and styrene as raw materials.A double modified APP（APP@SiO₂@PSNS）was prepared.It is found that the hydrophobicity and thermal stability of APP@SiO₂@PSNS are significantly improved compared with APP.The APP@SiO₂@PSNS flame retardant was coated on the surface of PET fabric to obtain M-APP@PET flame retardant hydrophobic fabric.The properties of the M-APP@PET fabric were characterized by TG,LOI,water resistance,UL-94,and SEM.The results showed that the hydrophobicity of the M-APP@PET fabric has been greatly improved.The vertical combustion experiment and the SEM of combustion residue indicated that M-APP could greatly improve the combustion and carbonization degree of PET fabric.TG result proves that M-APP can promote the carbonization of PET fabric during combustion.The LOI value of the APP@PET fabric was increased to 26.9%.Therefore,M-APP can improve the hydrophobicity,thermal stability,and flame retardancy of PET fabrics.