Flame Retardant Properties And Mechanical Properties Of Phosphorus-doped Graphene Oxide-grafted Carbon Nanotubes And Expanded Polypropylene Blends

This paper mainly studies the effect of graphene oxide(GO),the phosphorus-containing graphene oxide(P-FGO)functionalized with GO and the grafting of carbon nanotubes with P-FGO on the flame retardant properties of polypropylene.In this paper,the expandable flame retardant and polypropylene were composite to form the expandable polypropylene,and different amounts of GO,functionalized GO and functionalized GO grafted carbon nanotubes were added into the composite as the flame retardant coagent,to investigate the flame retardant and mechanical properties of the blend formed by them.We prepared the graphene oxide by hydrothermal method.And then added hypophosphite to GO get P-FGO functional modification,based on P-FGO to FTIR,XRD,TEM and SEM were characterized.GO and P-FGO were added to the polypropylene resin respectively to acquire PP/GO,PP/P-FGO composite material.Through the composite material limited oxygen index(LOI)test,we found the GO or P – FGO increased the LOI value of composites.The maximum LOI value were at 0.4wt % after there will be a trend of decrease after that.PP/GO,PP/P-FGO composite were tested using CONE calorimeter(CONE),thermogravimetric analysis(TG).Then we found that the peak heat release rate of the composite significantly reduce the amount of carbon residue and at 800 ?,the P-FGO than GO to PP in thermal stability performance is more outstanding.We examined tensile strength,bending strength,impact strength and a series of mechanical properties test and found that the addition of P-FGO reinforced to the mechanical properties of polypropylene than that of GO.The blend of PP/IFR/GO and PP/IFR/P-FGO was obtained by physical method,i.e.,melting blending.The flame retardant properties of the two blends were compared and it was found that the flame retardant effect of the blend reached the best when the amount of GO or P-FGO was 0.4wt%.The mechanical properties of the flame-retardant blends were compared and it was found that 0.4wt% of GO or P-FGO was added to the blends,and the mechanical properties were also the best.Carbon nanotubes(CNTs)were grafted onto functionalized graphene oxide(GO)by a one-step chemical "grafting-to" method.The hybrid materials were prepared by direct reaction of polyacrylacyl chloride and hydroxylated carbon nanotubes/functionalized graphene oxide mixture.The hybrid materials were added into PP/IFR system.The flame retardant properties of PP/GO and PP/P-FGO composites were analyzed by LOI test and UL-94 test.Tested by CONE calorimeter(CONE),thermogravimetric analysis(TG),tensile strength,bending strength,tensile strength,impact strength test on the thermal properties of the composite and validation,we proved that the mechanical properties of carbon nanotubes grafted functionalization of graphene on PP/IFR thermal stability,flame retardancy,mechanical properties and into charcoal has remarkable enhancement effect.By comparison,the grafting of phosphorous doped graphene oxide and carbon nanotubes enhanced the flame retardant properties and mechanical properties of polymer materials much more than that of non-grafted carbon nanotubes.Meanwhile,the addition amount to achieve the best flame retardant properties and mechanical properties also changed.