Thermophysical properties of polymer composite materials

Abstract

Subject of Study. The paper deals withthermophysical properties of a new polydimethylsiloxane potting compound. We study the principles of thermal conductivity and heat capacity changing depending on composition of materials in the temperature range of 25-175 ° C. The search of optimal composition of the compound is carried out providing thermal conductivity not less than 0.5 W/(м·К) and data set for the change prediction of thermo-physical properties depending on a compound composition. Methods. All the samples were produced by FSUE “Institute of Synthetic Rubber” on the basis of polymers used in serial production. All the compounds are two- or three-component materials based on a low molecular weight (liquid) polydimethylsiloxane caoutchouc made by a cold solidification method. Polyethylsiloxane PES-5, aluminum hydroxide, TiN, boron, zinc oxide are used as additives. The research of thermal conductivity and heat capacity are carried out by meters λ-400 and С-400by dynamic method of monotonic warming. Main Results. We have obtained new experimental data about the thermal conductivity and heat capacity of the polysiloxane compound, depending on the temperature and the concentrations of various fillers. With increasing of the filler concentration the thermal conductivity of the samples increases as well and the heat capacity decreases. It is shown that with increasing of temperature the thermal conductivity of compounds is falling by about 15%, and the heat capacity increases by about 60-70%. Practical Relevance. The retrieved data give the possibility to find the optimal composition of compound material that guarantees the following operational properties: thermal conductivity not less than 0.5 W/(м·К), long thermostability in the temperature range of -60 - +200 °C, the density of hydrogen nucleus not less than 1∙1014 nucleus/cm2 and the summary absorbed gamma radiation dose up to 300 Gy. The developed compound is being tested and can be applicable in the development of neutron shielding for the transportation of the used nuclear fuel in the nuclear fuel containers.