Thermal conductive polymer composite with similar PTC effect through latent foaming

At present, heat dissipation and heat insulation in power battery packs are two very important aspects in thermal management of electric vehicles. Heat dissipation is needed when the battery is working normally, but heat insulation is needed when the battery is thermal runaway. Now one surrounding material cannot meet these two opposite requirements at the same time. In this work, foaming agent as an initiator was used to prepare a thermal conductive polymer composite. Its thermal conductivity decreases sharply when the temperature rises to 160–180 °C, which shows a similar Positive Temperature Coefficient (PTC) effect. The main factors that affect its thermal conductivity, including foaming agent content, filler type, filler particle size and recombination are also discussed. By controlling the ratio of recombination, the change rate of thermal conductive PTC composite with latent foam structure can increase from only 4 times of formulation with only BN filler to 11 times of formulation with 80%Al2O3/20%BN below 190 °C. The infrared thermal imaging test further confirms that the prepared samples have good thermal conductivity at normal temperature, and the thermal conductivity decreases rapidly with the increase of temperature, confirming the effect of latent foam structure.