| Silicone rubber foam(SiF)has certain flame-retardant properties due to its special silicon-oxygen bond,but its flame-retardant and smoke-suppression properties cannot meet the application requirements due to the instability of the side chain groups.Inorganic silicon flame retardants are widely used in many polymer materials because of their advantages of non-toxic and environmental protection,low smoke generation,low heat release and high fire safety performance.However,they are limited by their poor compatibility and affinity with polymer materials.In this paper,surface modification technology and microencapsulation technology are adopted to modify inorganic silica-based flame retardants and add them to SiF in combination with zinc borate(ZB).The flame retardant and smoke suppression properties of SiF composites are systematically investigated using various characterization methods,and the flame retardant and smoke suppression mechanisms of SiF containing different modified inorganic silica-based flame retardants were initially revealed.The research work in this thesis is carried out in the following aspects.(1)Diatomite(Dia)and sepiolite(SEP)were poorly compatible with SiF.In this paper,Dia and SEP were modified by surface modification technology and microencapsulation technology,respectively.The results of particle size analysis,FTIR and XPS tests showed that the modified Dia and microencapsulated sepiolite(MSEP)have increased particle size,distinctive peaks and good inclusions compared with those before preparation.In addition,it can be seen from the SEM that the modified Dia and MSEP were successfully prepared.(2)In order to improve the flame retardant and smoke suppression properties of SiF,modified Dia,MSEP and ZB were compounded and added to SiF,and the flame retardant,smoke suppression and mechanical properties of SiF composites were investigated.On the one hand,the higher the additions of ZB and modified Dia,the better the flame retardant properties.When the addition amount was 5wt%,the peak heat release rate(PHRR)and peak smoke release rate(PSPR)containing 3.75wt%modified Dia/1.25wt%ZB/SiF were the smallest,which were reduced by 48.3%and 84.6%,respectively.In addition,mechanical property tests showed that the modified Dia could improve its compression and tensile properties.Modified Dia could effectively inhibit the release of CO2 with almost no CO.On the other hand,the higher the specific weight of SEP,the better the flame retardant and smoke suppressing performance.But the flame retardant effect did not change significantly after ZB exceeded 5wt%.MSEP/ZB could improve the TTI,FPI and FGI of SiF,and improve the fire safety performance;although the flame retardant and smoke suppression performance was significantly improved than the original,the effect was not as good as the sample with MSEP and ZB alone.The smaller the percentage of MSEP,the better the smoke suppression performance,and the significant in improving the mechanical properties of SiF.(3)Based on the good flame retardant and smoke suppression effect of modified Dia and MSEP compounded ZB,the flame retardant and smoke suppression mechanism was studied respectively.Test analysis showed that the special structure of Dia and SEP played an important role in flame retardant and smoke suppression.In addition,Dia and SEP could promote the formation of carbon,which was both a condensed phase flame retardant mechanism and a gas phase flame retardant mechanism.ZB could also form an insulating layer at high temperature and absorb heat to release moisture.Secondly,ZB would form boron silicate glassy material with Dia and SEP,which acted as a cohesive phase flame retardant. |
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