| With the development of science and technology, especially the electronic and electrical technology. The electronic products used in the life gradually become lighter, thinner and smaller. The circuit components in electronic equipments have a higher packing density. It will produce more heat in the equipments, It will affect the service life and safe reliability of electrical and electronic equipments when they are in overheating condition, so it is very important to solve the problem of heat dissipation. According to different application requirements, we carried out the study of thermally conductive polymer composites and prepared two kinds of thermally conductive polymer composites:thermally conductive and flame retardant polymer composite materials and thermally conductive paste.1.The preparation of the thermally conductive and flame retardant composites. The inorganic flame retardant magnesium hydroxide (Mg(OH)2) was incorporated into nylon 6 (PA6) matrix as the filler and their thermal, flexural and flame retardant properties were studied. The results show that the addition of Mg(OH)2 has improved the thermal conductivity and impact resistance of the composites. The vertical combustion rating is from V-2 up to V-0. In order to further improve the thermal conductivity of composites, we added the graphene nano platelets(GNPs) into the composites to prepare the Mg(OH)2/GNP/PA6 ternary composites and their thermal, flexural and flame retardant properties were studied. By adding the GNPs into the composites, the thermal conductivity and impact resistance of composites have improved, the flame retardancy of the ternary composites are V-0 rating.2. Thermally conductive paste is mainly composed of thermally conductive fillers and silicone oil. We prepared the thermally conductive paste made of the silicone oil with different viscosities. After compraring the maximal weight fraction of the fillers and the stability of the products at room temperature and high temperature, the silicone oil with the viscosity of 500cps is selected as matrix. The thermally expanded graphene and GNPs with different sizes were selected as fillers and the thermally conductive properties and heat resisting properties of the thermally conductive paste made of each filler respectively were studied. The results show that the CQ GNPs has the best performance and is selectede as thermally conductive filler.3. The binary themally conductive paste was prepared with 500 cps silicone oil as the matrix and GNPs, spherical alumina oxide(s-Al2O3), non spherical alumina oxide(ns-Al2O3), aluminum nitride (AlN), silicon carbide (SiC), zinc oxide (ZnO) as thermally conductive filler respectively. The themally conductive properties, heat resisting properties and viscosities of the binary thermally conductive paste were studied. The results show that the addition of thermally conductive filler can improve the thermal conductivity of the binary thermally conductive paste. The GNPs has a high thermal conductivity. After reaching the maximal weight fraction, the thermally conductive paste made of GNPs can not meet the application requirements of heat resistance and the thermally conductive paste made of inorganic fillers can meet the requirements. The s-A12O3 can be highly filled and the maximal weight fraction is 90wt%. The viscosities of the thermally conductive paste increase with the content of the fillers.4. In order to further improve the performance of the thermally conductive paste, GNPs was added into the thermally conductive paste to prepare the s-A12O3/GNP/SO ternary thermally conductive paste. The themally conductive properties, heat resisting properties and viscosities of the ternary thermally conductive paste were studied. The results show that the thermal conductivities of the thermally conductive paste increase with the content of GNPs. The ternary thermally conductive paste can meet the application requirements of heat resistance. The viscosities of the thermally conductive paste increase with the content of the fillers. |
PDF Full Text Request