| With the transformation of economic development and requirements to mode of production of green environmental protection,Chinese fiberboard industry demands for new type of high efficiency and inorganic green flame retardants increasingly.This study produced a new type of green environmental protection inorganic composite flame retardants used the MgAl-LDH and MP.The superior process parameters of retardant fiberboard,ratio optimization of MgAl-LDH and MP and additives of composite flame retardant were selected through analysis of the flame retardant performance and mechanical performance.Finally,the synergistic effect mechanism of the composite flame retardant was explored.The main research conclusions are as follows:(1)MgAl-LDH has a good flame retardant effect on the fiberboard but the mechanical strength of fiberboard decreased with the increase of adding amount.Using UF as adhesives,the mechanical strength of fiberboard added 10% flame retardants can reach the national standard GB/T 11718-2009.With 10 % additives,the oxygen index of MP was higher than that of MgAl-LDH,heat release rate and total heat release of MP were below MgAl-LDH,and so as to the weaken degree of mechanical strength of fiberboard.But the smoke release rate of MP was higher than that of MgAl-LDH.(2)Choose isocyanate(MDI)as adhesive to prepare the flame retardant fiberboard and optimize the process parameters by orthogonal experiments.The research shows that in the140~180 ? hot-pressing temperature,6~12 min hot-pressing time,6~10 % MDI additives,The effect of MDI additives and hot-pressing temperature on the strength of the fiberboard was significantly greater than the hot-pressing temperature.Considering MOE,MOR and IB overall,the optimal process parameters is 160? hot-pressing temperature,6 min hot-pressing time and 10 %.MDI additives.(3)Design full factorial experiment suppression with five levels of flame retardant compound proportion(MgAl-LDH: MP = 3:1,2:1,1:1,1:2 and 1:3)and three additives levels(10 %,15 % and 20 %)to prepare fiberboard.The heat release properties,smoke suppression performance and mechanical properties of the flame retardant fiberboard were analyzed.When the compound ratio is 1:1,under the same retardant additives,the heat release properties and smoke suppression performance of fiberboard were best,and the fire growth and heat release index of flame retardant fiberboard were the smallest,FGI 1.05 kW/m2 s.and THRI 2.15 MJ/m2.The flame retardant performance of the flame retardant fiberboard was improved with retardant additives increasing under the same proportion.Inorganic composite flame retardants had significant impact on the mechanical strength of fiberboard,and mechanical strength decreased obviously with retardant additives increasing.With 1:1 compound ratio and 20 % retardant additives,the MOE,MOR and IB of flame retardant fiberboard was respectively reduced by26.8 %,27.9 % and 26.8 %.Comprehensively considering various performance,1:1 compound ratio and 15 % retardant additives are superior.(4)Various indicators should be analyzed to determine whether a composite flame retardant have the synergistic effect.Due to different test mechanism,composite flame retardant showed no synergistic effect on the oxygen index,but showed the synergistic effect in the CONE test.Flame retardant mechanism of composite flame retardant is mainly gas phase and solid phase flame retardant effect is weak.MP can promote the decomposition of MgAl-LDH and decrease the decomposition temperature of MgAl-LDH to expand the exerting function temperature range of the composite flame retardant.The water of crystallization of MgAl-LDH absorbed heat to decomposition resulting in decline of surface temperature.The burning solid products covered on the substrate surface to block heat and oxygen supply to restrain burning.Ammonia gas,water vapor and carbon dioxide released from composite flame retardant absorbed the heat and diluted concentration of combustible gas and oxygen to get a better flame retardant effect. |
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