Compatibilizing and functionalizing polypropylene/polyethylene by in-situ exfoliating hexagonal boron nitride at interface

Recently, along with the serious waste polymer issues, the compatibilization and functionalization of immiscible polymers is regarded as a sustainable solution. In this work, for the first time, we explored the role of hexagonal boron nitride (h-BN) as an advanced compatibilizing and functionalizing agent for immiscible polypropylene (PP) and polyethylene (PE) composites through in-situ exfoliation at interface. The exfoliated structure was confirmed by X-ray diffraction and Raman spectra, with its thermodynamics drives in-situ exfoliation mechanism was proposed. The compatibilization effect of h-BN was evidenced by the enhanced tensile strength and Young's modulus of 28.0 MPa and 639.0 MPa of PP/PE/h-BN composite, which are 91.2% and 57.8% higher than PP/PE binary composite. Furthermore, the in-plane thermal conductivity was measured to be 0.87 W/mK at low h-BN loading of 15 wt% which is 2.6 times higher than the reference sample. Benefiting from the in-situ exfoliation, our sample showed the best thermal conductivity reinforcement effect (26.9%/vol%) as compared with the other reports. The heat management performance of our sample had also been revealed. Moreover, an additional experiment was performed to confirm that the concept proposed herein can be a sustainable route for waste polymers recycling. Thus, we believe the inclusion and in-situ exfoliation of h-BN could be a sustainable solution for the value-added recycling of waste polymers.