Effect Of Fabrication Of Phosphorus-nitrogen-based Flame Retardants On The Fire Resistance Of Epoxy Resin Study

Epoxy resin（EP）has been widely used in coatings,adhesives,composite materials,laminates,packaging and other fields because of its superior mechanical property,good chemical resistance,high adhesion to substrates,etc.However,EP is a highly flammable material and usually releases a large number of heat and toxic fumes during the combustion because of its composition and structure（hydrocarbon chain）.The human health and environment have been seriously threatened by those toxic fumes and heat.Therefore,it is critical to take methods to enhance the fire safety of EP.In this dissert,three phosphorus-nitrogen-based flame retardants were synthesized for improving the fire resistance of EP.The main research contents are listed as follows.（1）The phosphorus-nitrogen-based flame retardant diphenyl allylphosphoramidate（DPCA）was synthesized by the reaction of acyl chloride,and the flame-retardant epoxy resin composites（EP-DPCA）with the addition contents of 2 wt%,5 wt%or 8 wt%of the flame retardant were fabricated.The thermogravimetric analysis results exhibited that the carbon residues of EP was improved by 45%,in comparison with that of pure EP,with the addition of 8 wt%DPCA.Besides,the limited oxygen index（LOI）of EP-8%DPCA was increased to 27.8%.The cone calorimetry（CCT）results showed that the peak of heat release rate（PHRR）,peak of carbon monoxide production rate（PCOPR）and peak of carbon dioxide production rate（PCO₂PR）were declined by 41%,33%and 43%,respectively,compared to that of pure EP.The improvement of fire safety of EP is mainly caused by the quenching effect,dilution effect in the gas phase and the catalytic carbon-forming effect in the condensed phase of the flame retardant.（2）To further improve the flame retardant properties of epoxy resins,the lower oxidation state of phosphorus and phosphorus-nitrogen-based flame retardant N-allyl-P,P-diphenylphosphinic amide（DCA）with was synthesized and it was incorporated into EP to fabricate EP composites（EP-DCA）.The results revealed that the LOI value of EP composite was increased to 33%and the UL-94 V-1 rating was achieved,with the addition of 8 wt%DCA.Besides,the PHRR of EP-8%DCA was reduced by 37%,as compared to that of pure EP.Thermogravimetric analysis results showed that the degradation rate of the composites containing 8 wt%DCA was reduced by 35%,in comparison with that of pure EP.The results of UV-vis analysis demonstrated that the transparency of the composites containing 5 wt%DCA decreased by only 5.9%.（3）The fire safety of EP was significantly increased with the addition of nitrogen-phosphorus-sulfur-based flame retardant,due to the synergistic effect between nitrogen-phosphorus and sulfur element.Therefore,the nitrogen-phosphorus-sulfur-based flame retardant P,P-diphenyl-N-（2-（thiophen-2-yl）ethyl）phosphinic amide（SFDC）was prepared via the acyl chloride reaction and the flame-retardant EP composites（EP-SFDC）were fabricated.The UL-94 results revealed that EP-8%SFDC pass the V-1 grating.Besides,the cone calorimetry results demonstrated that the PHRR,total heat release（THR）,peak smoke production rate（PSPR）and total smoke production（TSP）of EP composite were declined by 14%,14%,24%and 15%.The above shows that the flame retardants had the functions of high-efficiency flame retardancy,suppression of smoke release and reduction of heat release,and its flame-retardant EP has high fire safety.