Cu(0) And Cu(?) Decorated Graphene Hybrid On Improving Fireproof Efficiency Of Ammonium Polyphosphate On Epoxy Resins

The copper compound has the catalytic effect of catalyzing carbonization and oxidizing carbon monoxide,at the same time,it has the function of synergistically enhancing the carbon strength and compactness of the expanded flame retardant system.The specific surface area of graphene oxide is large,and its surface contains a large amount of oxygen-containing functional groups?such as hydroxyl,carboxyl and epoxy groups?.These functional groups has excellent solution proessability and chemical reactivity,which makes them become ideal carriers for metal compounds.Interestingly,metal decorated graphene has the advantages of restraining the aggregation of graphene sheets,improving the catalytic activity of metal compounds,and increasing the dispersion and compatibility of graphene and metal compounds in polymer matrixes.Therefore,in this paper,graphite oxide?GY100?,ammonia?NH₃·H₂O?,copper acetate?Cu?CH₃COO?₂·H₂O?and hydrazine monohydrate?N₂H₄·H₂O?are the main raw materials,which are stripped by ultrasonic microwave heating,ion exchange method,chemical thermal reduction method and high temperature calcination method to sequentially synthesize copper ion-loaded graphene oxide(Cu²⁺-GO),copper element-loaded reduced graphene oxide?Cu-rGO?and copper oxide-loaded graphene?CuO-GNS?.Then,Cu²⁺-GO,Cu-rGO and CuO-GNS were incorporated into EP/APP composite and their effects on flame retardancy,smoke and toxic gases reduction,as well as thermal decomposition behavior were investigated.In addition,the gaseous and condensed pyrolysis products were analyzed in detail to explain the flame-retardant and smoke-suppressant mechanisms.The main work of this paper and the main research results obtained are as follows:?1?Cu²⁺-GO,Cu-rGO and CuO-GNS hybrids were successfully prepared.The crystal structure and element oxidation state were characterized by XPS and XRD.And it was found that the characteristic peaks corresponded to the standard cards,indicating that Cu²⁺-GO,Cu-rGO and CuO-GNS were successfully prepared.The morphology of the synergist was analyzed by SEM and TEM,indicating it was found that Cu²⁺,Cu and CuO particles were successfully loaded on graphene oxide and graphene sheets.In addition,the spacing between Cu²⁺-GO,Cu-rGO,and CuO-GNS copper frit lattice fringes is 0.24 nm,0.20 nm,and 0.26 nm,respectively.The measured fringe spacing is approximately equal to the spacing calculated using the Bragg formula,further confirming the structure of the three hybrids.Thermogravimetric analysis?TGA?results show that the introduction of Cu²⁺,Cu and CuO improves the thermal stability of graphene.?2?Cu²⁺-GO,Cu-rGO and CuO-GNS were used as synergists to synergistically enhance the flame retardant efficiency of ammonium polyphosphate expanded flame retardant epoxy resin.The fracture surface morphology of the epoxy resin flame retardant composite material was observed by SEM,indicating that the compatibility can be obviously improved by the additon of extra hybrids(Cu²⁺-GO,Cu-rGO and CuO-GNS).In addition,the limit oxygen index?LOI?,vertical combustion?UL-94 VB?and cone calorimeter?Cone?evaluate difference of the synergistic flame retardant efficiency of the three hybrids in EP/APP.LOI and UL-94VB test results show that the three hybrids and APP all have the synergistic flame retardant effect.On controlling the mass ratio of APP to hybrids as 14:1,the minimum loading of APP to get V-0 can be further reduced to 16.80 wt%,21.47 wt%and 20.53 wt%,respectively.Therefore,the synergy efficiency Cu²⁺-GO>CuO-GNS>Cu-rGO.Cone test results show that Cu²⁺-GO,CuO-GNS,and Cu-rGO can cooperate with APP to reduce the peak heat release rate?PHRR?,total smoke release?TSP?,and carbon monoxide release?COP?of EP.Cu²⁺-GO has a better effect on synergistically reducing PHRR,while CuO-GNS has a better effect on synergistically reducing COP.?3?Thermogravimetric analysis?TGA?,thermogravimetric-infrared combined?TG-FTIR?,X-ray photoelectron spectroscopy?XPS?,Raman spectroscopy?Raman?and scanning electron microscope?SEM?were used to study the flame retardant and smoke suppression mechanism of epoxy resin.The test results show that Cu²⁺is easier to convert into intermediates of different oxidation states than Cu and CuO,and can catalyze the rapid formation of protective carbon layer which rich in P?V?and Cu?II?by EP/APP.Cu²⁺-GO is better than Cu-rGO and CuO-GNS on synergistic flame retardant efficiency.CuO can better oxidize CO to CO₂ through the Cu⁰?Cu⁺?Cu²⁺redox cycle,so it exhibits better smoke suppression effect and reduces the release of toxic gases.