Research On The Performance Of Flame-retardant Epoxy Resin And Graphene-enhanced Flame-retardant Epoxy Resin

In this study,a phosphorus-nitrogen flame retardant,1,5-bis?3-hydroxyphenyl?amino-1,5-bisdibenzo[c,e][1,2]oxaphosphine-6-oxide pentane?GAP-DOPO?,was synthesized with 3-aminophenol,glutaraldehyde and9H,10H-9-Oxa-10-phosphaphenanthrene-10-oxide as raw matreials.Two phosphoramide flame retardant,6,6'-?1,4-phenylenebis?azanediyl??bis?dibenzo[c,e][1,2]oxaphosphorus-6-oxide??PDAB-DOPO?and 6,6'-?piperazine-1,4-diyl?bis?dibenzo[c,e][1,2]oxa-6-phosphine oxide??PiP-DOPO?,were prepared by Atherton-Todd reaction using p-phenylenediamide,piperazine,DOPO and cabon tetrachloride?CCl₄?as raw materials.The Poly?1,3-cyclohexyl dimethylamine spiro pentaerythritol diphosphate?was synthesized as an intumescent flame retardant curing agent using phosphorus oxychloride?POCl₃?,pentaerythritol?PER?and 1,3-cyclohexyl dimethylamine as raw materials.And a phosphorus modified graphene oxide?P-m-GO?was prepared by redox reaction using graphite,sulfuric acid,phosphorus pentoxide,potassium persulfate,potassium permanganate,hydrogen peroxide and phosphorous acid as raw materials.In the chapter 2 and chapter 3,the synthesis conditions of three phosphorus nitrogen flame retardants were discussed.The structure and thermal stability of three phosphorus nitrogen flame retardants were studied by FTIR,¹H-NMR and TGA.Three flame retardants were used to flame retardant epoxy resin?EP?.The flame retardancy and mechanical properties of the composites were studied by LOI,UL94,TGA,SEM,tensile and impact tests.The results show that the three flame retardants can obviously improve the flame retardant performance of EP,but the mechanical properties of the composite system decrease.When GAP-DOPO was used as flame retardant,and the phosphrous content reached 1.76wt%in the flame retardant EP system,the LOI was 22.6,the UL94 could pass the V-0 test.When PDAB-DOPO was used as flame retardant,the phosphorous content reached1.65wt%in EP composites,the LOI was 27.3,the UL94 passed V-0 test.When the PiP-DOPO was used as a flame retardant,the phosphorus content reachen1.50wt%in the EP system,the LOI was 27.5,the UL94 could pass V-0 test.Overall,all three phosphorus-nitrogen flame retardants shown a good flame retardant effect on the EP.In the chapter 4,the synthesis conditions of PCDSPB was discussed.The structure and thermal stability of PCDSPB were studied by FTIR,MS and TGA.And the PCDSPB was used as an intumescent flame retardant curing agent for EP.The flame retardancy and mechanical properties of the composites were studied by LOI,UL94,TGA,SEM,CCT,TG-FTIR,tensile and impact tests.The results show that the addition of PCDSPB has a good intumescent flame retardant effect for EP,but will reduce the mechanical properties.When the phosphorus content reached 1.74wt%in the flame retardant EP,the LOI was 27.9 and the UL94 could pass V-0 test.At the same time,the results of CCT and TG-FTIR shown that the addition of PCDSPB could decrease the PHRR,THR and the concentration of flammable gas released during the decomposition process,which had a significant effect on the flame retardant EP.The digital photos after CCT test confirmed the addition of PCDSPB has a good expansion effect,so PCDSPB is a good intumescent flame retardant for EP.In the chapter 5,a phosphorus modified graphene oxide?P-m-GO?was prepared by the redox method and characterized by FTIR,UV-Vis,XRD,SEM and TGA.Compared with the graphene oxide?GO?,it still has a good lamellar structure,the heat resistance was improved when the phosphorous element was introduced,and it has a higher residual amount at 800?.The flame retardancy and mechanical properties of the flame retardant EP were studied when the P-m-GO was added into flame retardant EP.The results shown that the addition of GO or P-m-GO would cause decreasing of the LOI,compared with GO,P-m-GO had a little influences for the LOI,which indicated that the incorporation of phosphorus reduced the help combustion effect.The mechanical properties test showed that the addition of GO didn't improve the mechanical properties of EP composites.However,the mechanical properties had an obviously improve when the P-m-GO was added into EP composites.When the amount of P-m-GO was 0.3wt%?relative to the mass of E-51?,the flame retardant composites had an maximum mechanical properties,the tensile strength was 49.3MPa,impact strength was 9.5kJ/m².P-m-GO has a good enhancement effect for APP flame retardant EP,and the flame retardant performance has a less influence.