Research On Phenyl Silicone Rubber Nanocomposites

High-power light-emitting diodes have got widespread attention from scientists and engineers worldwide in recent years owing to their high efficiency, fast response, energy saving, environmental protection and other fine features characteristics. In comparison with common LED, power LED will produce a higher light intensity, which emit more heat and more short-wave radiation. Then higher temperatures will accelerate the failure of the light-emitting diodes, which greatly reduces the use of the device life. Therefore, the encapsulation materials for high power LED should possess high UV light shielding efficiency to prevent the leakage of ultraviolet light, while maintaining high visible light transparency, high thermal conductivity and ultraviolet irradiation resistance.Silicone resins show a great potentiality for high power LED packaging owing to their excellent weather resistance, high temperature resistance and stability of chemical; and become the first choice of high-power LED encapsulation. However, the optical performance and overall performance of the existing silicone materials to be further improved to meet the needs of high-power LED encapsulation. This article carries out from two aspects.First, in order to improve the optical properties of the silicone rubber, high phenyl phenyl silicone rubber and high hydrogen silicone oil were designed and fabricated, and then cured the high refractive index silicone rubber. Phenyltrimethoxysilane (PTMS), diphenyl dimethoxysilane (DPDS), dimethyl dimethoxysilane (MSDS), hexamethyldisiloxane (MM), vinyl trimethoxy silane (VTMO), reaction conditions of reaction temperature, reaction time and amount of catalyst were choosed as factor to synthesis high phenyl silicone rubber. Research showed that the viscosity ratio and refractive index of reaction was greatest impact by high phenyl silicone rubber:PTMS:DPDS:MSDS:MM:VTMO= 3:2:1.5:0.3:0.96 (molar ratio). The obtained silicone rubber present a higher refractive index (1.55) and viscosity (18725/mPas). Then, tetramethyl cyclotetrasiloxane (D H4), cyclic mixture of methylphenylcyclosiloxanes (D Me,Phn), tetramethyldisiloxane(HMM), reaction time and temperature were choosed as factor to synthesis high phenyl hydrosilicone oil. Research showed that the viscosity ratio of reaction was greatest impact by high phenyl hydrosilicone oil:D H4:DMe,Phn:HMM=6:4:0 (molar ratio), The obtained silicone rubber present a high refractive index (1.52) and viscosity (1052/mPa-s).Secondly, in order to improve overall performance of silicone rubber prepared previously. Nano-TiO2, SiO2, ZrO2 and AlNaO6Si2 surface-modified with silane coupling agent incorporating into different phenyl content silicone rubber were designed and fabricated. Then, the mechanical properties, optical properties, dielectric properties, thermal conductivity of phenyl silicone rubber nanocomposites were systematically studied. The results showed that nanoparticles treated with KH550 coupling agent, the tensile strength of phenyl silicone rubber nanocomposites increases firstly and then decreased. When nano SiO2, TiO2 and ZrO2 and AlNaO6Si2 content were 0.03wt%, the prepared nanocomposite materials present good mechanical properties, which were 0.54MPa,0.59MPa,0.55MPa,0.54MPa respectively. Refractive index of the phenyl silicone rubber nanocomposites increased with particles content. When the nano SiO2, TiO2, ZrO2 and AlNaO6Si2 content were 3wt%, the prepared nanocomposite kept good refractive index, which was 1.587,1.573,1.571 and 1.566 respectively. Under a small amount particles (<0.03wt%), the refractive index of high phenyl silicone rubber were obviously increase by AlNaO6Si2 and nano-SiO2. However, the refractive index of the phenyl silicone rubber was steady increase by them. The dielectric constant of phenyl silicone rubber nanocomposite increases with particles content. The impact of nano-SiO2 and AlNaO6Si2 on phenyl silicon rubber is higher than the high phenyl silicone rubber. Volume resistivity of phenyl silicone rubber nanocomposites increased with particles content. When nano-SiO2, TiO2, ZrO2 and AlNaO6Si2 content were 3wt%, the prepared nanocomposite kept the highest volume resistivity. The volume resistivity of phenyl silicone rubber composites adding with modified ZrO2 and TiO2 increased from 2×1013Ω·cm to 20×1013,40×1013n-cm respectively. The volume resistivity of composite adding with modified AlNaO6Si2 and SiO2 increased from 2×1013Ω·cm to 5×1013,6×1013Ω·cm respectively. Thermal conductivity of the phenyl silicone rubber nanocomposites increased firstly and then decreases. When the nano-ZrO2, AlNaO6Si2 content were 0.03wt%, and nano-TiO2, SiO2 content were 0.6 wt%,1%, the prepared nanocomposite presented best thermal conductivity, which were 0.306,0.436,0.339 and 0.464W·m-1·K-1 respectively.