Preparation and Properties of Thermally Conductive Co-POM Materials Filled with Composite of h-BN and Al₂O₃

Copolyoxymethylene(Co-POM) material has ordered molecular structure without side-chain, and is called metallic plastic because of its good dimensional stability, mechanical properties, processability and insulation. Co-POM material is widely applied in many fields, such as electronics and electrical appliances, plumbing and irrigation equipments, automobiles. However, the application of Co-POM is limited in the fields of microelectronics and LED lighting due to its low thermal conductivity. Therefore, it is crucial to prepare the Co-POM material with high thermal conductivity and excellent mechanical properties. To this regard, we blend some thermally conductive fillers with Co-POM resin in order to improve its thermal conductivity. Hexagonal boron nitride (h-BN) and α spherical alumina (Al₂O₃) can be as thermally conductive filler, due to their higher thermal conductivity than Co-POM. Co-POM thermally conductive materials were prepared with single or composite fillers. The effects of filler content and composition ratio on the thermal conductivity, tensile property and micro-morphology of thermally conductive Co-POM materials were investigated in this work. The results showed that the thermal conductivity Co-POM materials could be improved by filling with h-BN or Al₂O₃, the more the content of filler was used, the higher thermal conductivity of filled materials was obtained. Notably, the thermally modified effect of h-BN was better than Al₂O₃. Furthermore, in case the mass ratio of h-BN and Al₂O₃ was at 1:1, the resulting thermally conductivity of Co-POM material (the mass fraction of filler was 20%, the same below) was higher than the Co-POM material prepared with 30% (mass fraction) Al₂O₃, and approaching to the thermal conductivity of Co-POM prepared with 20% (mass fraction) h-BN. Additionally, the tensile strength of Co-POM material filled with composite showed slight changes. Therefore, the use of composite fillers can reduce the added content of filler, and thereby decrease the cost of materials preparation.