Study On Nano Flame Retardancy Containing Phosphorus In Epoxy Resin Composites

In recent years,halogen free flame retardant has become one of the research focuses in the field of flame retardant.Among them,using silicon and phosphorus flame retardant compounds is one of the hot spots.Nano flame retardant technology is another direction that many researchers are devoted to.The rearch emphasis is that independently prepared 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-montmorillonite nanocompound(DOPO-MMT)and new ammonium polyphosphate–montmorillonite nanocompound(APP-MMT)are applied to epoxy resin(EP)and their effects to flame-retard EP are studied,also the decisive factors to the intumescence mechanism and the blowing-out effect were also studied.This thesis can be devided into three main parts.First part includes preparing DOPO-MMT nanocompound,using it to flame-retard EP composites and studying its flame retardant mechanism.A new method to prepare a kind of DOPO-MMT nanocompound is proposed.This kind of DOPO-MMT nanocompound has nano structures and is added into epoxy resin(EP).A better flame retardant performance is obtained when compared with the physical mixture of DOPO and MMT.In the DOPO-MMT nanocompound,MMT layers are intercalated by DOPO and layer spacing is extended which make layers easy to exfoliated in EP matrix.Those exfoliated MMT layers have better interaction with DOPO and make the UL-94 level of EP reach V-0 level and have the least heat release in cone calorimetry.Gas phase flame retardant from DOPO and condensed phase flame retardant from MMT work together to suppress the flame during combustion and give better flame retardancy to EP.Second part includes using new APP-MMT nanocompound to flame-retard EP and studying the flame retardancy of it and its flame retardant mechanism.APP-MMT nanocompound which is prepared by our research group is added into epoxy resin E-44 to make a new flame-retarded epoxy resin composite.And after the research,the nanocompound precedes the physical mixture of APP and MMT in flame retardancy.The composites can arrive V-0 level in UL-94 test and has an obvious reduce in heat release in cone calorimetry.Also a firm and completed char layer can form which indicate the flame retardancy of condensed phase of APP and MMT can be fully played.It means the nanocompound can induce the expansion of char and to inhibit the occurrence of combustion behavior.Third part studies the flame-retardant mechanism of APP-MMT nanocomposite and the mixture of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and octaphenyl polyhedral oligomeric silsesquioxane(DOPO + OPS)in flame retarded epoxy resin.In this paper,the analysis of flame retardant mechanism of EP composites modified with APP-MMT nanocomposites and DOPO + OPS mixture indicated that the APP-MMT nanocomposites made the epoxy resin behave as the intumescence mechanism,while the DOPO + OPS mixture made the epoxy resin show blowing-out effect.When it comes to the flame retardant efficiency,it is found that the DOPO + OPS mixture had more excellent performance in terms of LOI,UL-94,HRR and so on,and APP-MMT nanocomposites performed better in the reduction of TSR.It is found that the release rate of the pyrolysis gases and the the different structures of the char layers make the flame retardant mechanism of the two flame retardant behave as intumescence mechanism or blowing-out effect through the analysis of the pyrolytic gaseous products of EP composites and the microstructure and the infrared absorption of the char layers after CONE test.