| As we all know,PP is very flammable in real life,which poses a great threat to people’s daily life,property and life safety.Therefore,flame retardant of PP is very important.Polyvinyl chloride(PVC)is not easy to burn because of it contents chlorine,but soft polyvinyl chloride(PVC)is easy to burn because of adding a large number of plasticizers.At the same time,because PVC produces a large number of cis-olefins during combustion and then cyclizes to form aromatic compounds,and further generates polycyclic aromatic resins.Aromatic compounds are pyrolyzed into polyolefins,benzene,HCl,olefins and alkanes,etc.These intermediate products further generate black smoke,which seriously reduces the probability of people escaping from the fire site.Therefore,it is very important to study the flame retardancy of polypropylene and flexible polyvinyl chloride.In halogen flame retardants,bromine flame retardants are more widely used than chlorine flame retardants because of their high flame retardant efficiency,abundant raw materials and little influence on the mechanical properties of materials.However,bromine flame retardants are banned by more and more countries because they decompose into toxic and harmful substances at high temperature during the flame retardant process,which has a long-term impact on human beings and the environment.It is very important to develop an efficient and environmentally friendly flame retardant.Intumescent flame retardant has gradually become a new trend of flame retardant development because of its environmental protection and high flame retardant efficiency.In this paper,MPP(melamine polyphosphate),APP(ammonium polyphosphate)and the newly synthesized triazine charring agent M were compounded in a certain proportion to obtain a new triazine flame retardant with high efficiency and environmental protection.Compared with other intumescent flame retardant systems of ammonium polyphosphate,a new acid source-MPP(melamine polyphosphate)was mixed with the newly synthesized charring agent M in a ratio of 2:1 and then added into PP,which effectively improved the flame retardancy of PP.After adding 25% flame retardant,the vertical combustion grade of PP reaches V0 grade,the limiting oxygen index reaches 28%,and the mechanical properties of PP decrease in an acceptable range.Compared with the same type of flame retardant on the market,the new compound flame retardant has no precipitation.The newlysynthesized charring agent M was compounded with MPP(melamine polyphosphate)and APP(ammonium polyphosphate)in a ratio of 2:1,and added to two copies of zinc oxide(zinc oxide)in different soft PVC.The results showed that the vertical combustion grade of PVC reached V0 grade,and the limiting oxygen index reached 27% and 28% respectively.Smoke density reached 63 and 59 respectively,which decreased by 12.5% and 21.3%compared with pure soft PVC,and mechanical properties decreased by 11.9% and 11.7%respectively,which were still acceptable. |
