Synthesis Of DPO Derivatives And Their Application In Epoxy Resin

In order to overcome the flammability of epoxy resin,novel phosphorus-containing flame retardants were desigened and synthesized successfully using diphenylphosphine oxide(DPO)an d 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO)as raw materials in this study:(bis(4-hydroxyphenyl)-methyl)-diphenyl-phosphine-oxide(DPO-PHE),1-(bis(4-hydroxyphenyl)-methyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO-PHE),((4-hydroxyphenyl)(phenylimino-methyl))-diphenylphosphineoxide(DPO-PHM)and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-((phenylimino)(4-hydroxyphenyl)-methyl)(DOPO-PHM).The structures of obtained samples were confirmed by NMR,MS and IR.The obtained flame retardants DPO-PHE,DOPO-PHE,DPO-PHM and DOPO-PHM were used in the modification of bisphenol A diglycidyl ether epoxy resins(DGEBA).Results indicated that although the decomposition temperature of epoxy resins decreased with the introduction of flame retardants,all flame retardants could effectively improve the flame resistance of epoxy resin matrix.When DPO-PHE was used as the flame retardant,the modified epoxy resin could pass UL-94 V-0 test with the P content of 0.7 wt%;for DOPO-PHE,0.9 wt%of P content was needed to pass the same level.While using DPO-PHM or DOPO-PHM,0.5 wt%of P content was enough to pass UL-94 V-0 test.Results of cone calorimetry test(CONE),scanning electron microscopy(SEM)and pyrolysis-gas chromatography/mass spectrometry(Py/GC-MS)suggested that in the modification of epoxy resin,the four flame retardants could act through the gas-phase mechanism.After combustion,a continuous and dense layer,isolating heat and oxygen,was formed on the outer surface of EP/DPO-PHE-P-0.9 and EP/DOPO-PHE-P-0.9 samples.Finally,the water absorption abilities of DPO-PHE and DOPO-PHE modified samples and epoxy resin matrix were compared.Results shown that DPO-PHE and DOPO-PHE could both reduce the water absorption of epoxy resin.