| Polypropylene(PP)is an important thermoplastic material,which is widely used in electrical equipment housings,vehicle transportation,furniture decoration and other fields.However,PP is easy to burn,and will release a large amount of smoke and toxic gas at high temperature,which severely limits its application,so it needs to be flame-retardant treatment.Among many flame retardant technologies,intumescent flame retardants(IFR)have attracted more and more attention in flame retardant applications due to their environmental protection and high efficiency.However,IFR still has problems such as poor water resistance and low flame retardant efficiency.Greatly restricting its promotion and use.In response to the above problems,this article synthesized microencapsulated IFR with excellent water resistance by sol-gel method,and prepared a water-resistant flame-retardant PP composite material.Moreover,in order to further improve the flame retardant efficiency of IFR,aluminum hypophosphite(AHP)was used as synergist to form a synergistic flame retardant system with previously synthesized water-resistant IFR.Polypropylene composites with synergistic flame retardant function were prepared,and their thermal stability and flame retardancy were also studied in this paper.The main content of this article is as follows:1.In order to solve the problem of poor water resistance of the traditional intumescent flame retardant,the hydrophobic modified microencapsulated ammonium polyphosphate(M-APP)and carbonization agent(M-CA)were prepared by sol-gel method and used in the preparation of water and flame retardant PP composites.The contact angle test results show that the contact angles of m-app and m-ca are 135.11°and 137.89° respectively.The flame retardancy test showed that the flame retardancy of PP Composites with 30 wt%hydrophobic modified IFR(m-app/m-ca=3:1)was significantly improved,the limit oxygen index(LOI)test result reached 36.8%,and UL-94 passed V-0.The peak heat release rate and total heat release of the PP composites descended from 1011.77 to 134.43 kW/m2 and 100.58 to 6.86 MJ/m2,respectively.The peak smoke production rate and total smoke release descended from 0.13 to 0.0056 m2/s and 1453.09 to 74.82 m2/m2,respectively.The PP composite with M-APP/M-CA=3:1 also exhibited excellent water resistance,and it could still reach UL-94 V-0 after soaking in 70? water for 168 h.2.Low flame-retardant efficiency is currently a key technical bottleneck hindering the widespread use of flame retardants.In order to further improve the flame retardant efficiency,the addition amount of flame retardant is reduced Here,aluminum hypophosphite(AHP)was used as a synergist of the previously prepared microencapsulated intumescent flame retardant(IFR)M-APP/M-CA system to further improve the flame retardant efficiency of polypropylene(PP)composites.The composites thermal stability and flame retardancy were investigated by limit oxygen index(LOI),vertical combustion(UL-94)test,theormgravimetric analysis(TGA),TG-IR test,cone calorimetry(CCT)test,X-ray scanner(XPS),scanning electron microscope(SEM)test,X-ray photoelectron spectroscopy(EDS)analysis.The results show that when the total amount of flame retardant remains unchanged at 25 wt%,the LOI value of PP composite increases from 28.7%to 32.9%after introducing 1.25 wt%AHP,and the UL-94 test grade of sample reaches V-0 from V-2.Thr decreased from 99.05 MJ/m2 of pure PP and 14.2 MJ/m2 of PP composites without AHP synergist to 10.75 MJ/m2,and TSR decreased to 92.2 m2/m2 compared with pure PP(1910.8 m2/m2)and PP composites without AHP synergist(126.1m2/m2).Figure 29 table 11 reference 172... |
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