Manufacture And Study On Flame Retardant And Thermal Conductivity RTV Silicone Rubber

A flame retardant and thermal conductivity RTV silicone rubber is one type of liquidsilicone rubber. The silicone rubber has many excellent properties,such as excellentliquidity, easy operation, fast sulfuration speed rate, easy to use. And this RTV siliconerubber is increasingly important for hot emission and flame retardant of the electronicdevices. First,The preparation of α, ω-dihydroxyl polydimethylsiloxane （107rubber） bythe method of equilibrium polymerization at alkali catalyst were described. A flameretardant and dealcoholized RTV silicone rubber was prepared with107rubber,cross-linking agent and flame retardant fillers. The effect of several retardants （such asMPP, MP, Mg（OH）₂/Al（OH）₃/MP, MP/OMMT）on flame retardant and physical properties,dispersion state in silicone rubber as well as thermal stability of RTV silicone rubber hadbeen studied. Second, a thermal conductivity and dealcoholized RTV silicone rubber wasprepared with107rubber, cross-linking agent and thermal conductive fillers. The effectof several thermal conductive fillers（such as PMSQ、Fe₂O₃/MgO，ZnO/MgO，Si/MgO）on thermal conduativity and physical properties, as well as thermal stability of RTVsilicone rubber also had been studied.Third, a flame retardant and thermal conduativityRTV silicone rubber was prepared with107rubber, cross-linking agent, flame retardantfillers and thermal conductive fillers.1. Study on flame retardant silicone rubber composits:（1） MPP-filled flame retardant silicone rubberThe silicone rubber had measure up to UL-94V-0standards with adding more than30phr MPP （100phr107rubber basis）.The peak of Heat release rate and smoke releaserate of RTV silicone rubber along with the increase of MPP decreased.The tensilestrength, tearing strength and hardness of RTV silicone rubber along with the increase of MPP increased, but the breaking elongation decreased. When MPP was used, thedecomposition temperature of the silicone rubber decreased.（2） MP-filled flame retardant silicone rubber.The RTV silicone rubber did not possess excellent flame resistance until50phr MP.But with the increase of MP, the initial decomposition temperature of the flame-retardedand dealcoholized RTV silicone rubber diminished. In addition, MP could be very evenlydistributed in the RTV silicone rubber, which kept tensile strength and elongation at breakof RTV silicone rubber well when the amount of MP increasing to50phr.（3） Mg（OH）₂/Al（OH）₃/MP flame retardant silicone rubberThe comprehensive performance of the rubber was the best when Mg（OH）₂/Al（OH）₃/MP at the ratio of1:1.5:2.5. It was found that a better synergistic flame retardant effectof Mg（OH）₂/Al（OH）₃/MP flame retardants can come into being, which further built upflame retardancy, thermal stability and smoke suppression of silicone rubber composites.（4） RTV silicone rubber/organ-montmorillonite flame retardant nanocompositesOMMT not only did not significantly weaken the MP’s flame resistance but also caninhibit the MP from facilitating thermal decomposition of the silicone rubber, whichincreased its initial decomposition temperature. It was found that OMMT can somarkedly promote the generation amount of combustion residue of the silicone rubberthat a hard barrier layer was formed. In addition, OMMT can significantly enhancemechanical properties of intumescent flame retardant silicone rubber filled MP.2. Study on thermal conduativity silicone rubber composits:（1） PMSQ-filled thermal conductivity silicone rubber composits.The silicone rubber had good thermal conductivity with adding5phr PMSQ （100phr107rubber basis）, from30℃to150℃. With the increase of adding amount of PMSQ,the tensile strength and breaking elongation ration decreased. Volume resistivity with theincrease of the PMSQ first increased, then decreased. Adding amount of3phr PMSQ,volume resistivity increased1.68times. PMSQ can improve flame retardant propertiesabout the RTV silicone rubber.（2） Composite thermal conductive filler-filled thermal conduativity silicone rubberWith the same proportion of fillers, tensile strength and breaking elongation ration ofdifferent mixed fillers of silicone rubbers were different. When two of the thermalconductivity filler ratio is1:1, break elongation and tensile strength have extreme value,because the mixed fillers can form the collaborative reinforcing effect. With the sameproportion of fillers, the order of thermal conductivity of silicone rubber is Si/MgO/silicone rubber>ZnO/MgO/silicone rubber>Fe₂O₃/MgO/silicone rubber.Twokinds of thermal conductive filler mixed can form collaborative thermal effect.3.The flame retardant and thermal conductivity RTVsilicone rubber:The flame retardant and thermal conductivity RTV silicone rubber concluding acertain weight of the components has many excellent properties, such as moderateviscosity, easy operation, on-site vulcanization, easy to use. Thermal conductivity is0.6⁰.8w/（m· k）, flame retardant level to UL-94-V-1. When burning the rubber releasedsmall quantity of heat and small quantity of smoke, according with environmentalprotection requirement.