Thermal conductivity enhancement of PLA/TPU/BN composites by controlling BN distribution and annealing treatment

Polylactic acid (PLA)/thermoplastic urethane (TPU)/boron nitride (BN) composites were successfully prepared, the effect of microstructure evolution along with the compositional change and annealing treatment on the thermal conductivity of composite was investigated. Owing to the selective distribution of BN in low-viscosity TPU phase, the compactness of thermally conductive networks in PLA/TPU/BN composites was reinforced. Thereby, the thermal conductivity of PLA/TPU/BN composites was obviously improved by 21.6% at 25 wt-% BN than that of PLA/BN composites. Moreover, research on the effect of annealing treatment on the thermal conductivity of composites found that the crystallinity of PLA had been improved by the recrystallisation and the thermal conductivities of composites were enhanced. Finally, due to the possible hydrogen bonding between PLA and TPU, PLA/TPU/BN composites showed no serious deterioration in mechanical properties. This work endows new enlightenment to fabricate composites with great thermal conductivity without causing serious damage to mechanical properties.