Preparation And Research Of Flame Retardant High Temperature Vulcanized Silicone Rubber

Silicone rubber(SR) is a kind of heterochain elastomer with high and lowtemperature resistance, electrical insulation, air permeability and physiological inertiaetc,which allow SR can be widely used in many areas, such as aerospace, wire andcable, medical aspects etc. however, the flammability of SR limits its applications inthese areas. In order to improve the flame retardant properties of SR, adding flameretardant to the compounding system is the most effective and most direct way.This article used aluminum hydroxide (ATH), antimony trioxide (Sb2O3)andammonium polyphosphate (APP) as flame retardants.The effect of use of ATH flameretardant alone, ATH and Sb2O3synergistic flame retardant and ATH and APPsynergistic flame retardant on the properties of SR was studied.in addition, a modifier（hexamethyldisilazane）was used to the surface modification of ATH, and theirdifferent modification effect to SR with different process is studied. Experiment alsostudied the effect of components (silica vulcanizing agent and vinyl content etc.)otherthan flame retardants on the mechanical properties,flame retardant properties and heatresistance of SR.The factor include the influence of amount of silica, the variety andamount of vulcanizing agent and vinyl content of raw rubber on SR.While using ATH flame retardants only, the more the amount of ATH used, thebetter the SR flame retardant property is.when the amount of ATH is60phr, oxygenindex reached38%and vertical burning level is FV-0. But at the same time, themechanical properties of SR showed a sharp decline, while the amount of ATH is60phr, the tensile strength decreased by28.0%and tearing strength decreased by43.4%;And the heat stability of the SR was damaged also.In order to solve the problem of damaged to mechanical properties of SR whichATH made, the experiment used hexamethyldisilazane (HMDS) as surfacemodification to modified ATH with three kinds of modified process. Experimentsindicated that using modified process three to modified ATH has the best effect on improving mechanical properties of SR. The tensile strength and tear strengthincreased by18.0%and17.6%respectively than before. This paper also studiedsynergistic flame retardant effect of ATH/Sb2O3and ATH/APP, founding that usingSb2O3instead of partial ATH depress the flame retardant properties of SR.Sb2O3andATH do not have good synergistic flame retardant effect, but the mechanical propertyis improved. When using APP instead of part ATH, found that the flame retardanteffect is better than the separate use of ATH. When the total amount of flameretardants is60phr, the oxygen index of SR which used ATH and APP synergisticflame retardant was40%, better than38%which used ATH only.In order to optimize the comprehensive property of SR further,the effect ofcompound in SR compounding system on the property of SR were studied. Studyshowed that when using vinyl content of the raw rubber is0.13%, the amount of fumedsilica is40phr and dosage of vulcanizing agent DBPMH is1.5phr, SR has the bestproperty.