Synthesis And Flame-retardant Properties Of Novel Phosphorus And Nitrogen Flame Retardants

Organic phosphorus flame retardants with low halogen,low smoke and other characteristics,nitrogen flame retardants with non-toxic,environmentally friendly features.The introduction of nitrogen in phosphorus compounds,the flame retardant molecules will contain both phosphorus and nitrogen elements,its flame retardant effect is significantly better than only containing phosphorus compounds,and it will replace the halogen-based flame retardants.So it is meaningful to develop novel phosphorus and nitrogen flame retardants.Two different structures phosphorus and nitrogen flame retardant DOPO-DMG and TDPP were synthesized respectively,The DOPO-DMG was synthesized by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO),4,4-Diaminodiphenyl methane(DDM)and glutaric dialdehyde as raw material.And the TDPP was synthesized by 2,4,6-tris(dihydroxy-methylamino)-1,3,5-triazine(HMM)and phenylphosphonic dichloride(PPD)as raw material.The optimum technological conditions for synthesis were discussed.Meanwhile,the structures of products were characterized by Fourier transform spectrometry(FT-IR)and Nuclear magnetic resonances(NMR).At the same time,the thermal stability of flame retardant was investigated by thermo gravimetric analysis(TGA).Under a nitrogen atmosphere,the 5% weight loss temperature(T5%)of DOPO-DMG and TDPP are 250? and 293 ? respectively,and they can meet the requirements of the preparation process conditions applied to the polymer material.The DOPO-DMG was used in epoxy resin(EP)and the TDPP was used in linear low density polyethylene(LLDPE)for flame retardance test.The results showed that when DOPO-DMG with 2.01% phosphorus content was added to the epoxy resin,the LOI can reach 28.8,the UL 94 can pass V-0,the tensile strength and impact strength was 39.1 MPa and 5.2 KJ/m2 respectively,and the char yield at 800? was improved to 25.63%?And when TDPP with 6.22% phosphorus content was added to the LLDPE,the LOI can reach 29.3,the UL 94 can pass V-0,the tensile strength and impact strength was 9.1 MPa and 16.9 KJ/m2 respectively,and the char yield at 800? was improved 15.5%?The morphology of carbon residue of the two flame retardant systems was analyzed by scanning electron microscopy(SEM).The surface of pure epoxy resin and pure polyethylene did not have carbon layer on the surface after the burning surface without the density of carbon layer,The flame retardant system with flame retardant can form a relatively dense and expanded carbon layer after combustion.In summary,DOPO-DMG and TDPP have good flame-retardant properties to epoxy resin and polyethylene respectively.