Study On The Preparation And Flame Retardant Properties Of Graphene Modified Mineral Materials

Polymers have been widely used in coal industry with excellent comprehensive properties such as corrosion resistance,light weight,easy processing and high mechanical properties.At present,the polymer materials used in coal mines include epoxy resin,polyurethane,water-borne paint and so on.But when this kind of polymer product is used in the dangerous environment of gas and coal dust explosion in coal mine,besides ensuring good performance,it should have reliable safety performance in particular.In this paper,graphene oxide?GO?was functionalized by silane coupling agent and boric acid,and functionalized graphene oxide?fGO?with silicon-boron network structure was successfully prepared.Subsequently,fGO was applied to epoxy resin?EP?,rigid polyurethane foam?RPUF?and waterborne epoxy resin coatings?WEP?,and its flame retardancy and flame retardant mechanism were studied.Specifically completed the following four parts:1.With 3-aminopropyl triethoxysilane and H₃BO₃ as raw materials,GO was functionalized by silane coupling agent grafting method,and the suitable conditions were determined to prepare fGO.The results show that new functional groups of B-O,Si-O-Si and C-O-Si on the surface of fGO materials appear,the lamellar spacing increases from 0.34 nm to 0.83 nm,and the thermal stability and carbon residue of fGO are obviously improved.It can be seen that H₃BO₃ is successfully grafted onto the surface of GO.2.Ammonium polyphosphate?APP?was selected as the main flame retardant of EP.GO and fGO were used as synergists for flame retardant of EP.In order to ensure high flame retardancy and excellent mechanical properties,the ratio of 0.1 wt%GO or fGO and 14.9 wt%APP was selected.The LOI of 0.1 wt%fGO/14.9 wt%APP/EP reached 28.8%,and the peak heat release rate?PHRR?,total heat release?THR?of the samples decreased by 42.96%,13.93%and 12.57%respectively compared with pure EP.Scanning electron microscopy?SEM?showed that fGO could promote EP decomposition to produce continuous,compact,smooth and excellent expansive carbon layer,which was also the key to improve flame retardancy.3.Expansible graphite?EG?and dimethyl methylphosphonate?DMMP?were used as the main flame retardants,and the flame retardant ratio of EG:DMMP=3:1 and fGO was selected to synergize flame retardant RPUF composites.The results showed that when 7.5 phr EG/2.5 phr DMMP was mixed with 0.25 phr fGO,the LOI value of RPUF-7 sample reached 28.1%,and the tensile strength,elongation at break and compressive strength of the sample were 41.0%,50.6%and 30.0%higher than that of RPUF-4,respectively.Thermogravimetric analysis?TG?and SEM analysis showed that fGO significantly improved the thermal stability and residual carbon content of RPUF flame retardant composites,enhanced the continuity and compactness of the carbon layer,effectively inhibited the release of heat and flammable organic volatiles,thereby improving the flame retardancy of RPUF.4.Melamine polyphosphate?MPP?,pentaerythritol?PER?and melamine formaldehyde resin?MF?were used as intumescent flame retardants?IFR?and fGO in WEP coatings.The results showed that when 25.0 phr MPP,12.5 phr PER,12.5 phr MF were mixed with 0.083 phr fGO,the fire resistance time of WEP-4 increased by 60.4%compared with WEP-1.Meanwhile,the PHRR and THR values of WEP-4 decreased from 229.7 kW m-2 to 128.1 kW m-2 and from 44.2 MJ/m2 to 31.3 MJ/m2,respectively.SEM analysis shows that fGO nano-materials can effectively enhance the structure of carbon layer,which has a good morphology,height and structure,and has a good protective effect on the internal materials of the matrix.