| Due to the excellent properties,such as corrosion resistance,outstanding electrical insulation,perfect mechanical rigidity,easy processing and good adhesion,epoxy resin(EP)is widely applied in civil construction,aviation,printed circuit board,adhesive and insulating device.However,just like most polymers,EP has the inherent flammability and high risk of tremendous yield of toxic smoke after ignition,so the security of the application of epoxy resin needs to be improved.Therefore,the development of multifunctional flame retardant epoxy resin materials have high theoretical significance and application value.Combined with the domestic and foreign researches,based on the halogen-free and high-efficiency flame retardant layered double hydroxides(LDHs)which contain transition metals,a series of novel modified CuAl-LDHs were synthesized by co-precipitation method.Then added the modified CuAl-LDHs in EP to prepared flame retardant nanocomposites,studied the structures,thermal properties,combustion properties and smoke suppression performance of flame retardant nanocomposites systems,and discussed the flame retardant mechanism of the nanocomposites.Disodium phenylphosphate(PPAD)and the traditional surfactant sodium dodecyl sulfate(SDS)were used as modifiers to modified copper-aluminum LDHs by co-precipitation method,respectively.Then got Cu Al(PPAD)LDHs and CuAl(SDS)LDHs.Study the morphology and structures of these LDHsby X ray diffraction(XRD)and transmission electron microscopy(TEM).Prepared the EP/LDHs nanocomposites,researched the thermal stability and the combustion performance of these composites through thermogravimetric analyzer(TG),oxygen index(LOI)and cone calorimeter analysis(CONE).The results showed that the thermal stability,flame retardancy and smoke suppression performance of EP/CuAl(PPAD)LDHs were all better than EP/CuAl(SDS)LDHs composites,the peak heat release rate(PHRR)of EP/4wt%CuAl(PPAD)LDHs can be reduced by 30% compared with EP/4wt%CuAl(SDS)LDHs.Using SDS as dispersant to ultrasonic disperse carbon nanotubes(CNTs),then the three dimensional nano-hybrids carbon nanotubes(CNTs)grafted CuAl-LDHs(CNTs-OLDHs)prepared by co-precipitation method with different content of CNTs,then added the hybrids into EP matrix.The morphology and structures of CNTs-OLDHs and EP/CNTs-OLDHs nanocomposites were observed by XRD,TEM and FT-IR.It showed that the hybrids were successfully synthesised,and CNTs did not destroy the structures of OLDHs,but also can enlarge layer spacing of OLDHs.At the same time,it found that the hybrids can make CNTs and OLDHs finely disperse in EP matrix,and formed 3D network structures in matrix.The thermal stability and flame retardancy of EP/CNTs-OLDHs nanocomposites were investigated by means of TG,LOI,UL-94,CONE and MCC.The CONE results indicated that with low addition of hybrids,the PHRR of theEP nanocomposites can be reduced by up to 50.5% and the total heat release(THR)can be reduced by up to 32%,due to the good dispersion of CNTs-OLDHs.TG and MCC test implied that the content of CNTs in the hybrid controlled in certain range could not only reduce the heat release rate(HRR),but also improve the thermal stability of EP composites,the char residual can increased from 13.8% of pure EP to 25.7% in 700 ?.The environmental friendly and low cost alkyl polyglycoside coprecipitation(APG)were introduced into the interlayer of LDHs.Then the organic Cu Al(APG)LDHs served sound flame retardance in EP matrix,evaluated by CONE and LOI.Series of test results showed that APG and LDHs played a good thermal stability and flame retardant synergistic effect,and the smoke suppression effect was particularly good,compared with the pure EP,the peak value of smoke release rate and total smoke production decreased by 23% and 34%,respectively. |
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