| Silicone rubber?SR?is an organic elastomer with alternating siloxane bonds.Compared to others rubber,the groups connected to the side chain are usually functional,which impart chemical inertness and stability to silicone rubber.It is widely used in civil and industrial fields.However,silicone rubber is flammable and can burn quickly under ignition.It is necessary to improve its flame retardancy.At present,phosphorus-based flame retardants play an important role in the flame retardancy of polymer materials because they contain phosphorus flame retardant elements in their structure.In this paper,two new flame retardants were synthesized using 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide?DOPO?as flame retardant intermediate from the pers-pective of phosphorus flame retardants and were applied to silicone rubber substrates to investigate the flame retardancy of composite materials.?1?A new polyphenylene ring flame retardant polybis?4-hydroxypheyl?-2-?6-oxo-6H-dibenzodibenzo[c,e][1,2]oxaphosphino-6-yl?methylene succinate?PHDO?was prepared by the melt condensation reaction between[?6-oxo-6H-dibenzo[c,e][1,2]oxphosphahex-6-yl?methyl]succinic?DDP?and 1,4-benzenedimethanol,and it was added to silicone rubber at a certain ratio to prepare silicone rubber composite material.In FTIR spectrum,the peak at1585 cm-1 of the itaconic acid?ITA?molecule disappeared and the peak at 2388 cm-1 of the DOPO molecule disappeared.In the NMR spectrum,hydrogen resonance absorption peaks at 8.8-8.9 ppm in DOPO and 5.69 ppm and 6.14 ppm in ITA disappeared,and new resonance absorption peaks of hydrogen appeared at 2.4-2.9 ppm.A new ester-based absorption peak appeared at 170 ppm in the solid carbon spectrum.All these indicate that PHDO has been successfully prepared.after adding PHDO,the thermal stability and flame retardancy of silicone rubber composites are improved.Tmax of SR/PHDO composites is105°C higher than that of pure SR.When 10 parts of PHDO were added,Heat release rate?HRR?decreased from 465 KW/m2 to 318 KW/m2,the peak decreased by 31.6%.Total heat release rate?THR?decreased from 68.13 MJ/m2 to 42.27 MJ/m2,the peak decreased by 37.7%.Smoke release rate?SPR?decreased from 0.195 m2/s to 0.158 m2/s,the peak decreased by 19%.Total smoke production?TSP?decreased from 25.01 m2 to 14.46 m2,the peak decreased by 42.2%.The limit oxygen index?LOI?has been increased from20.5%to 27%,and the flame retardant level has reached V-1 level.?2?Dehydration condensation product?HCP?was prepared through the addition reaction and dehydration condensation reaction of DOPO,vinyltrimethoxysilane and?3-aminopropyl?triethoxysilane.The HCP-PA flame retardant with high phosphorus content was prepared by reacting HCP with phytic acid?PA?,and it was compounded with OMWCNTs to prepare silicone rubber composites.FTIR analysis showed that the infrared peak at 2385 cm-1 of the DOPO molecule and the infrared peak at 1600 cm-1 of the VTS molecule disappeared.NMR spectral analysis showed that the P-H bond of DOPO and the resonance absorption peak of hydrogen at C=C of VTS disappeared.XPS structure analysis showed that the binding energies of-NH2and-NH3+in HCP-PA were 400.8 e V and 401.5 e V,respectively.These showed that the amino group in HCP reacted with PA.Adding a small amount of HCP-PA have a good flame retardant effect.When HCP-PA was added to 5 parts,HRR decreased from 436 KW/m2 to 288 KW/m2 and the peak decreased by 33.9%.After mixing it with OMWCNTs,the HRR of SR/HCP-PA-5 composite material was reduced from 288 KW/m2 to 251 KW/m2 when OMWCNTs was added as one part.The SPR decreased from 0.118 m2/s to 0.087 m2/s.The LOI has been increased from20.4%to 28.4%,and the flame retardant level can reach V-0 level. |
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