| Polyurethane(PU),like most other polymer materials,although widely applied,is extremely flammable due to its poor heat resistance,and produces a large amount of toxic fumes,which endangers the safety of personal property.With the rapid growth of the national economy and the rising GDP per capita,the state has vigorously advocated green development strategies.Therefore,research on the surface modification treatment of flame retardant PU is urgent.However,many flame retardants used in flame retardant PU have the disadvantages of poor water resistance,easy agglomeration and poor compatibility with substrates,which seriously affect the use of flame retardants,so the surface modification treatment of flame retardants appears especially important.Studies have shown that microencapsulation technology is an effective method that can both improve the water resistance of flame retardants and the flame retardant effect.In recent years,microencapsulation technology has been favored in the field of polymer flame retardant because of its simple operation method and obvious coating effect.In this thesis,utilizing bio-based flame retardantPSTM as the core material and polyurethane,melamine resin and silicone-gel as the wall materials,three series of nine microencapsulated flame retardants were prepared and added to PU for flame retardant modification.The main research contents are summarized as follows:(1)Utilizing pentaerythritol and 2,4-toluene diisocyanate as raw materials,PSTM as the core material,DMSO and 1,4-dioxane as the solvent,dibutyltin dilaurate as the catalyst,and Tween-80 as the emulsifier Agent,using in-situ polymerization method to synthesize polyurethane microcapsulated flame retardant(MPSTM).Then add ethylene glycol,polyethylene glycol and tetraethyl orthosilicate to modify the wall material components to synthesize EMPSTM,PMPSTM and SMPSTM.The structure and morphology of the microcapsules were characterized by FT-IR,XPS,SEM,EDX,and Mapping.The thermal properties of the four microcapsules were studied by TGA/DTG.The results showed that the carbon retention rate of the four microcapsules at 800 ? was significantly increased compared with the core material.The flame retardant properties of PU/MPSTM,PU/EMPSTM,PU/PMPSTM and PU/SMPSTM with different flame retardant additions were investigated through LOI and UL-94.It was found that the LOI of four flame retardant PUs varies with the amount of flame retardant used increase and increase,when the usage is 30%,the LOI of PU/MPSTM,PU/EMPSTM,PU/PMPSTM and PU/SMPSTM are 26.4,26.4,26.5 and 26.3 respectively,their UL-94 reach V-0 rating.The water solubility test of PMPSTM and SMPSTM showed that both microcapsules can reduce the solubility of PSTM in water to differentdegrees.Further tests on its water resistance and mechanical properties showed that:after soaking in water at 75? for 8 hours,the LOI of PU/PMPSTM was higher than that of PU/SMPSTM;TGA analysis showed that the two kinds of polyurethane microcapsule flame retardant systems had good thermal stability.The bending strength and tensile strength of PU/PMPSTM and PU/SMPSTM all increased the amount of flame retardant added increases and decreases,and the mechanical properties of PMPSTM are superior to SMPSTM.Cone test results show that compared with pure PU,the peak heat release rate(PHRR),total heat release amount(THR),smoke generation rate(SPR)and smoke release rate(RSR)of PU/PMPSTM-30% are less than blank PU The parameters were reduced by 23.2%,8.4%,36.4%,and 35.6%,respectively.The parameters of SPR,TSP,TSR,and TSP all decreased to varying degrees.(2)Utilizing melamine and formaldehyde as raw materials,PSTM as the core material,and water and ethanol as the solvent,melamine resin microcapsulated flame retardant(MFPSTM)was synthesized by in-situ polymerization.Then use EG,PEG and TEOS to modify the wall material components to synthesize EMFPSTM,PMFPSTM and SMFPSTM.The structure and morphology of the four microcapsules were characterized by FT-IR,XPS,SEM,EDX and Mapping.TGA results also show that the residual carbon rate of the four flame retardants at 800? is higher than that of PSTM.The LOI of the four flame retardant PUs increases as the amount of flame retardant added.When the added amount is 30%,the LOI of PU/MFPSTM,PU/EMFPSTM,PU/PMFPSTM and PU/SMFPSTM are 25.2,25.5,26.5 and 26.7respectively,and their UL-94 reaches V-0 rating.The results of thermogravimetric test show that the two kinds of microcapsule flame retardant systems have good thermal stability.The water solubility test of PMFPSTM and SMFPSTM found that the mass loss rate of SMFPSTM was lower than that of PMFPSTM after 8 hours of soaking.Further testing the water resistance and mechanical properties of them,the results showed that the LOI of PU/SMFPSTM and PU/PMFPSTM after immersion showed a downward trend,and the water resistance of PU/SMFPSTM was better than PU/PMFPSTM;With the increasing amount of flame retardants in PU/SMFPSTM and PU/PMFPSTM,the impact on mechanical properties is becoming more and more serious,and the mechanical properties of PU/SMFPSTM-20% are better than PU/PMFPSTM-20%.Cone test results show that compared with pure PU,the peak heat release rate(PHRR),total heat release amount(THR),smoke generation rate(SPR)and smoke release rate(RSR)of PU/SMFPSTM-30% are less than blank PU They decreased by 38.9%,34.7%,30%,and 29.1%,respectively.The parameters of SPR,TSP,TSR,and TSP all decreased to varying degrees.(3)Utilizing TEOS as the wall material,ammonia as the catalyst,PSTM as the core material,OP-10 as the emulsifier,the sol-gel method is used in the water-ethanol mixed solvent system to synthesize the silicone-gel microencapsulated flame retardant SPSTM.The structure and morphology were characterized by FT-IR and SEM.TGA researched the thermal performance of SPSTM,and the results showed that: compared with the core material,SPSTM increased the residual carbon rate from 11.16% to 22.68%.The water solubility and dispersibility test of SPSTMshowed that the solubility of SPSTM in water was significantly lower than that of PSTM,and the dispersibility in paraffin was good.The results of the LOI and UL-94 studies show that: the LOI of PU/SPSTM gradually increases with the increase in the amount of flame retardant.When the amount is 30%,the LOI of PU/SPSTM is 26.2,and UL-94 reaches V-0.TGA results showed that the thermal stability of silicon-gel microcapsule was good.The water resistance and mechanical properties of PU/SPSTM were further investigated.The results showed that the LOI of PU/SPSTM-20% after immersion showed a downward trend,and the silicone-gel began to play a protective role on the core material after 6h.The tensile strength and bending strength of SPSTM decrease with the increase of adding amount.Cone test results show that compared with pure PU,the peak heat release rate(PHRR),total heat release amount(THR),smoke generation rate(SPR)and smoke release rate(RSR)of PU/SPSTM-30% are less than that of blank PU They decreased by 35.8%,14.5%,52.5%,and 51.9%,respectively,and the parameters of SPR,TSP,TSR,and TSP all decreased to varying degrees. |
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