The interface of thermal conductive polymer composite matrix and filler can affect the overall thermal conductivity of the composite. However, limited by traditional testing technologies, it is difficult to study the interface thermal conduction mechanism from microscopic view. In this paper, the interface thermal conduction mechanism of boron nitride (BN)/low density polyethylene (LDPE) composites was studied by scanning thermal microscope (SThM), and the interface thermal properties of the BN/LDPE composites were analyzed quantitatively. The test process of SThM was simulated by finite element analysis, and the interface thermal conduction process at the inorganic-organic interface was revealed. The results show that with the increase of BN content, the thermal conductivity of the composite increases. When the mass fraction of the BN reaches 20%, the thermal conductivity of the composite increases by 22%. The sample morphology in micro-nano scale and the voltage distribution image reflecting the thermal properties were obtained by SThM, it is found that the thermal conductivity interface width of the BN/LDPE composite is 150–200 nm. At the area that two BN particles are in contact with each other, the high thermal conductivity area increases, and the thermal conductivity interface width changes little. The fitting curve between thermal conductivity and the square of output voltage is obtained by testing the standard samples, and the interface thermal conductivity of the BN/LDPE composites is calculated to be 0.33–39.81 W/(m·K). The simulation results show that the probe tip can distinguish the filler, interface, and matrix, and the thermal conductivity of the composite increases with the increase of the interface width and thermal conductivity.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |