Study On The Thermal Conductivity Of NR Composite Filled With CNTS

Recently, thermal conductive rubber has been gained widespread attention, and significant results had been achieved. With the rapid development of modern science and technology, the requirements of properties, preparation, diversity of thermal conductive rubber are becoming more and more strict.Firstly, the effect of crosslinking density on NR thermal conductivity was studied with controlling the dosage of rubber auxiliaries. Results showed that:the thermal conductivity of NR was affected by the long polymer chain molecular tightness and movement of the materials which promoted the enhancement of the thermal conductivity together and were suppressed each other. At low temperature, the molecular chain movement played the leading role in thermal conductivity of NR and the molecular tightness did at high temperature. Then, preparing the sample with different blending conditions, the influences of carbon nanotubes on thermal conductivity of NR composites were studied.Researches showed that:With the increase of CNTs, the thermal conductivity of CNTs/NR composites prepared by mechanical blending increased steadily. The thermal conductivity of composites varied by 12vol% of CNTs from 0.224 W/(m·K) to 0.242W/(m·K) with temperature changing. The tensile strength of composites offered upgrade firstly than descending latter tendency and reached the highest point at 6vol% of CNTs. CNTs in NR harmed the elongation at break. The longer the length and the larger the diameter of CNTs is, the more enhancement of the thermal conductivity and mechanical reinforcement effect is. A-MWNT greatly improved the thermal conductivity of composites, but significantly reduced the mechanical properties.In this paper, we prepared Fe3O4-CNTs/NR blend by solution blending, and obtained NR composites filled with aligned Fe3O4-CNTs in magnetic field. Due to the increase of magnetic field of Fe3O4-CNTs with the increase of the coating rate, Fe3O4-CNTs were better aligned and the thermal conductivities of composites increased gradually. The thermal conductivity of composites was improved by filled with Fe3O4-CNTs, and as the amount of CNTs over 8vol%, the thermal conductivity increased rapidly. Magnetic field intensity was used to improve the orientations of Fe3O4-CNTs parallel to magnetic film and thermal conductivity of composites. When Fe3O4-CNTs were unevenly distributed due to their movement by attracted to magnets in field exceeds about 500mT, the thermal conductivity decreased. As the angle of magnetic field closed to the angle of the measurement, the thermal conductivity of composites increased. When magnetic field was oriented at right angles to the measurement, the thermal conductivity was the lowest. When the angle between magnetic field and measurement was greater than 45 degrees, the thermal conductivity of composites filled with aligned Fe3O4-CNTs was lower than composites without magnetic orientation.