Preparation And Flame Retardancy Of Epoxy Resin Composites Containing Silicon Or Phosphorus

Epoxy resin, with its excellent mechanical and chemical properties, has been widelyused as adhesive, electrical insulation, surface coating, and composite matrix. However, itsinherent flammability limits its specific applications. Thus, improving the flame retardancyof epoxy resin can lead to its more widespread applications. Concerning the flameretardancy of epoxy resin, halogenated compounds meet flame-retardant requirements.However, halogen-containing compounds produce corrosive and poisonous smoke duringburning, thereby harming human health and posing risks to environment safety. Therefore,researchers from both scientific and industrial fields introduce halogen-free flame retardantsinto epoxy resin to obtain flame-retardant epoxy resin composites. The main contents are asflows：1. A series of epoxy resin nanocomposites containing octaammonium polyhedraloligomeric silsesquioxane modified montmorillonite (OAPOSS-MMT) was prepared via insitu polymerization by using4,4’-diaminodiphenyl sulfone as curing agent. Theincorporation of OAPOSS-MMT into epoxy resin matrix showed exfoliated structures,which improved the thermal stability and flame retardancy of epoxy resin matrix. BecauseOAPOSS-MMT did not produce gas during thermal decomposition, the gas speciesproduced by epoxy resin nanocomposites were the same as those of control epoxy resin.2. Hexaphenoxycyclotriphosphazene (HPCTP) was synthesized by a nucleophilicsubstitution reaction, and its chemical structure of HPCTP was then characterized byFourier transform infrared spectroscopy as well as1H and31P nuclear magnetic resonancespectroscopy. The synthesized HPCTP was incorporated into the diglycidyl ether ofbisphenol A to prepare epoxy resin composites using4,4’-diamino diphenylmethane ascuring agent. The UL–94V–0rating was easily achieved with the addition of HPCTP, andthe heat release intensity simultaneously decreased. Evaluation of thermal properties demonstrated that the resulting composites achieved high thermal stability with high charyields. Analysis of residual chars confirmed that HPCTP could enhance the thermal stabilityand flame retardancy of epoxy resin.3. Epoxy resin composites containing HPCTP and octapropylglycidylether polyhedraloligomeric silsesquioxane (OGPOSS) were prepared using4,4’-diamino diphenylmethaneas curing agent. High char yields indicated that both HPCTP and OGPOSS could induce theformation of intumescent char layer, which retarded the degradation and combustionprocess of epoxy resin. The reduction in peak heat release rate of epoxy resin compositecontaining15wt.%HPCTP was61%less than that of control epoxy resin. Meanwhile, otherflame-retardant parameters were also improved.4. The HPCTP and9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)were used to flame retard the N,N,N’,N’-Tetraglycidyl-4,4’-diaminodiphenylmethane epoxyresins. Thermogravimetric analysis of the flame retarded epoxy resins indicated that theincorporation of the flame retardants reduced the initial decomposition temperature ofepoxy resin. The increase in LOI value, UL-94rating was strongly dependent on thephosphorus content. The reduction in peak of heat release rate and total heat release showedthat the incorporation of flame retardants could improve the flame retardancy of epoxy resin,and showed a gas phase flame ratardancy mechanism.