In this work, approach to use of noncovalently modified carbon nanotubes is given for preparation of functional hybrid polymeric composite materials (HPCM) based on epoxy resin. Conductive glass-fiber plastics with resistivity in transverse and lengthwise direction 9.0Á3 10 2 and 30-50 Ohm cm, respectively, were obtained. The tetrafluoroethylene telomer and fluorocontaining organosilicon copolymer with amino groups were used as modifiers for carbon nanotubes. Thermal, electrical, and mechanical properties of the obtained materials were studied. The mechanism of the effect of noncovalent modification of carbon nanotubes on functional properties of HPCM was discussed. It was found, that type of modifier significantly affects the level of functional properties. The use of fluorocontaining organosilicon copolymer is more optimal in comparison with tetrafluoroethylene telomer. Thus, HPCM with carbon-fiber filler and this modifier has higher electrical conductivity and lightning strike resistance in comparison with nonmodified HPCM. This approach is promising to impart antistatic properties for glass-fiber plastics and increase lightning resistance of carbonfiber plastics.
The article is devoted to the evaluation of the effect of porosity on the effective thermal conductivity of thermal insulation materials. The main factors influencing the thermal conductivity of the material, such as density, the type of porous structure of the material and humidity, are considered. The method of measuring the thermal conductivity by the stationary heat flow method and the hot zone method is described. A method for calculating the effective thermal conductivity of fibrous materials is presented. A computational and experimental study of the effective thermal conductivity is carried out and the results are analyzed.
Carbon-ceramic composites are considered promising materials to be used in thermal protection shields of innovative descent vehicles that are currently being designed. The development of thermal shield material requires modelling its thermal-phase state under operational conditions. In this paper, physical and mathematical models are proposed for analysis of the destruction and radiation-conductive heat transfer in a porous carbon-ceramic composite material consisting of carbon fibres covered by silicon carbide. The models take into account all main physical and chemical processes of heating up and thermo-chemical destruction. A software package DMA based on the finite element method was developed, and modelling of heating up and destruction of the material was conducted. It was established that when the temperature was above 800 °С, the contribution of the radiation heat exchange became considerable. A comparison of the surface microstructures obtained through modelling and gas-dynamic testing in a plasmatron facility showed their qualitative agreement, while the mass loss did not exceed 16%.
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