Preparation And Properties Of Flame Retardant Ceramifiable Silicone Rubber

Ceramifiable polymer based composites is a novel fire-proof material.In normal condition it has the same properties of other organic polymers,while under fire condition,it can concrete strong ceramic layers which can perform a fire-safe capability.Silicone rubber has excellent electrical properties,chemical stability,moisture and water resistance,excellent resistance to high and low temperature and has excellent mechanical properties from-50 to 200 ?.Silicone rubber is half organic and half inorganic,which leads to lower heat release rate,lower total heat release and lower fire risk index comparing to other organic polymers.Therefore,fire-resistant ceramifiable silicone rubber has been widely studied and used.To achieve the ceramifiable property of silicone rubber,the normal way is to add some mineral filters to the silicone rubber matrix.In fire,filler and the pyrolysis of matrix will form a hard ceramic layer by eutectic reactions.The mechanism of ceramization is complicated,which requires extensive study.The good fire-resistant capability is usually achieved by high loading level of flame retardant fillers,However,doing this can reduce the mechanical properties of silicone rubber as well.To reach the balance among these properties,we need to blend them appropriately.In the meantime,the incompatibility between flame retardant fillers and silicone rubber matrix would weaken the flame retardancy,which requires novel flame retardants compatible with silicone rubber matrix.This paper summarizes the flame retardant ceramifiable silicone rubber system and the mechanism of flame retardancy and ceramic at first,the advances on the research and applications in fields of fire-resistant and ceramifiable silicone rubber are introduced in this part as well.Based on the analysis of ceramics silicone rubber foreign and domestic,we got a series of ceramifiable silicone rubber formulations by adjusting the ceramic additives systemly.By studying the synergistic effect of different general flame retardants in silicone rubber system,a flame retardant synergist with high flame retardant efficiency was created.a serial of novel flame retardants with good silicone rubber compatibility were synthesized;a group of fire-resistant ceramifiable silicone rubber composites with excellent comprehensive property were prepared.Several modem analysis and testing,such as Thermogravimetric differential scanning calorimetric coupled analysis(TG-DSC),X-ray diffraction analyzer(XRD),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),auto rheometer text,limiting oxygen index determination(LOI)and cone calorimeter test(CONE)were used to characterize the products.The main work and results are summarized as follows:1.The Influence of the combination of mica,wollastonite and diatomite on ceramifiable silicone rubber was studied.In fire,mica and the pyrolysis of silicone rubber will sinter,meanwhile,the layer structure attributes to form a solid ceramic body;wollastonite can form a crosslinked network structure that can strengthen ceramic body when combine with mica;diatomite can form a number of tiny hole structure in ceramic body which is advantageous to the decomposition of gas discharge,and to maintain the size of the ceramic body stability,and prevent the crack,when the mass ratio of 325mush mica and 800mush mica and wollastonite and diatomite is 3:3:2:0.89,bending strength and compression strength of the ceramic body can be reached to 8.14 Mpa and 8.14 Mpa.2.Silicone rubber loading sphere zinc borate has better creamic properties and better mechanical performance than silicone rubber loading ordinary zinc borate.Shrinkage of ceramic body can be maintained and a good ceramifiable property can be achieved by blending calcium carbonate with zinc borate appropriately.3.Optimizing ceramifiable silicone rubber system was prepared by systemic combination of ceramic fillers.Fire-resistant and ceramifiable silicone rubber with good comprehensive properties was prepared by studying synergistic effect of general flame retardants on the basis of the optimizing ceramifiable silicone rubber system,LOI values reached to 38.0,and FV-0 was obtained.4.A novel organosilicon flame retardant containing PEPA group was synthesized,which has good flame retardancy and good silicone rubber compatibility.Fire-resistant and ceramifiable silicone rubber with good comprehensive properties was prepared by adding the novel flame retardant into the optimizing ceramifiable silicone rubber system,LOI values reached to 32.5,and FV-0 was obtained,ceramic body surface of silicone rubber after heat preservation comes to being is flat and no crack.