Preparation Of Novel Graphene-Based Ternary Flame Retardant And Its Application In Polypropylene

Polypropylene(PP),as one of the most common and important thermoplastic universal plastics,has been widely used in automotive industry,building materials,electronic communications,aerospace and other fields because of its light quality,corrosion resistance,easy processing and low price.However,its own structural defects lead to high combustion,high heat release rate and heavy flaming drips phenomenon and other potential hazards,which seriously restricts its multifaceted applications.How to achieve the halogen-free flame flame retardancy of PP and maintain good comprehensive performance have always been an important topic and difficulty in academia and industry.This thesis summarizes the research progress of common PP flame retardants and the fire resistance technology through a large number of literature researches.As a new type of multifunctional material,graphene has been extensively developed and utilized,and its precursor,graphene oxide(GO),can produce various high-performance substances with different functions due to reactive functional groups.As a new type of organic-inorganic hybrid nanostructured material,cage silsesquioxane(POSS)can impart excellent heat resistance,flame retardancy and hydrophobic properties to polymers.9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO)has also been widely used in flame retardant applications of polymers or as flame retardant modifiers to enhance the fire resistance of materials.Considering the excellent properties of the above three substances and the call for solving the common defects of halogenated flame retardants as well as responding to environmentally friendly topics,this paper successfully proposes an effective and simple method to graft the POSS and DOPO onto the surface of GO nanolayer without halogenation to obtain a new graphene based flame retardant oapPOSS-GO-DOPO(P-G-D)that contains nitrogen,phosphorus and silicon flame retardant elements.Its structural characteristics were thoroughly characterized by FT-IR,Raman,XRD,NMR,XPS and TEM tests.TGA analysis showed that the amount of carbon residue of the prepared P-G-D flame retardant at 700?was 58.5%.Then,P-G-D and PP powders were melt-compounded to prepare PP composites.The limiting oxygen index(LOI)and vertical combustion(UL-94)showed that P-G-D has a significant flame retardant effect on PP.Cone calorimetry(CONE)also found that the peak heat release rate and total heat release rate P-G-D/PP composite was reduced by 78.0%and 44.9%compared with pure PP,respectively.In order to reduce the amount of traditional flame retardant added,the performance of the new graphene-based flame retardant combined with traditional intumescent flame retardant(IFR)on synergistic flame retardanting PP was further explored.TGA shows that its thermal stability is excellent and the amount of final carbon residue is significantly improved.LOI,UL-94 and microcalorimetry(MCC)tests have proved that they have good synergistic flame retardant effect,and maintain the good hydrophobicity of pure PP matierials.Furthermore,the introduced phosphorous,nitrogen and silicon hydrophilic groups do not show the negative effects on the surface hydrophobicity of flame retarded PP materials,which could broaden its scope of application.