Effect of Nano-ZrO2 on Properties of Room Temperature Vulcanization Phenyl Silicone Rubber

Abstract

In this study, nano-ZrO2, which was treated by silane couple agent, incorporated in phenyl silicone rubber at low concentration (≤3.0%) and cured by Room Temperature Vulcanized (RTV) method. The effects of different additive amount of nano-ZrO2 on the mechanical properties, thermal conductivity and electrical conductivity of phenyl silicone rubber were investigated. The thermal conductivity, tensile strength and volume resistivity of nanocomposites increased firstly and then decreased. The dielectric constant of nanocomposites decreased firstly and then increased with the content of nanoparticles. We were interested to find that phenyl silicone rubber had a maximum thermal conductivity (0.399W/(m·K)), a maximum volume resistivity (1.08×10 12 Ω·cm)and a minimum dielectric constant (2.775), with a definite total mass fraction of the particle (0.06%). Compared with the thermal comductivity of pure silicone rubber (0.130W/(m·K)), it increased more than three times in the addition amount of 0.06wt%. Moreover, the silicone rubber keeps a high tensile strength. Introduction Light emitting diode (LED) has received a great deal of attention for lighting in industries and research because of their energy efficiency and durability. Thus, LED is expected to be the most powerful candidate for lighting sources in the near future[1-4]. As a packaging material of LED, phenyl silicone rubber is an important material among silicon material, which is formed by introducing phenyl into the main chain of dimethyl silicone rubber. With excellent oxidation resistance, radiation resistance and low temperature flexibility make this class of materials very attractive candidate for use in the outdoor applications[5]. However, with the power of LED (light emitting diode) increased, it produced more heat and ultraviolet radiation, which usually leads to the epoxy resin cracking and yellowing, so HB-LED (high brightness light emitting diode) usually use high temperature resistance and resistance to ultraviolet radiation organic silicon resin as a packaging material[6,7]. But the thermal conductivity and mechanical properties of organic silicon materials are relatively low, so the inorganic substances usually need to be added in organic matrix to improve its thermal conductivity and refraction[8-10]. The method to improve the thermal conductivity and the mechanical properties of organic silicon are effective, but there are also defects. However, the raw nanoparticles aggregate much severely because of their large cohesive strength and poor compatibility with polymers when the naked nanoparticles are dispersed into the polymers. In this case, the particles/polymer composites often display poor mechanical and dielectric properties. For example, the electrical breakdown strength of the composites always decreased remarkably so that the particles/polymer composites would be used only at low electrical field[11]. Therefore, it is often necessary to seek suitable nanoparticles in order that they can be well dispersed in the polymer. A better interfacial interaction between the nanoparticles and polymer matrix could be obtained, which is beneficial to International Conference on Material Science and Application (ICMSA 2015) © 2015. The authors Published by Atlantis Press 677 the improvement of the mechanical properties and thermal conductivity of the composites. So far, nano-ZrO2 composites have been developed and mostly used in film materials as a wide range of applications in recent years, because of its excellent resistance to heat, optical properties, electrical properties, mechanical properties and chemical stability. The nanocomposites can be used for thermal barrier, insulation, wear resistance and anti-corrosion coating and optical devices, etc. The nano-ZrO2 composites can be widely used in aerospace, ferrous metallurgy, machinery manufacturing, optical, electrical and other fields, which prospects are very broad. Yang D[12] studied the effect of ablative properties on zirconium carbide or zirconia silicone rubber. Few researchers studied silicone rubber treated with nano-ZrO2, and focused on the effects of ZrO2 nanoparticles on the physics and chemistry properties of phenyl silicone rubber at low concentration (≤1.0%)[13-15]. In this paper, ZrO2 treated with silane couple agents were used to prepare nanoparticles/phenyl silicone rubber composites. The effects of the nanoparticles on mechanical properties, thermal conductivity and dielectric behavior of phenyl silicone rubber were investigated.