Advanced thermoplastic polyurethane/hexagonal boron nitride thermal conductors via elongational flow from the aspect of experiment and simulation

In this work, a novel melt blending approach for fabricating thermoplastic polyurethane (TPU)/hexagonal boron nitride (h-BN) composites using an elongational flow method was proposed. With 50wt% of h-BN, the thermal conductivity (TC) of composite produced by elongation flow is 2.9W/(m.K), compared with 2.41W/(m.K) for the composite produced by conventional shear flow method, indicating a significant improvement was obtained. The peeling of h-BN, which is responsible for increased TC, was proved and the peeling mechanism was proposed. Meanwhile, the effect of changed h-BN geometrical dimension during the peeling process on TC was investigated by lapped simulation. The result shows that thinner sheet thickness brings a higher lapped rate and a longer heat conduction path at the same h-BN content. Additionally, the importance of maintaining lateral dimensions is proved by the simulation. This strategy paved a new way to manufacture high thermal conductivity 2D nanosheet composites with a green and efficient method.