Intrinsic thermal conductive ultra-high molecular weight polyethylene via cyclic pulsating pressure

The miniaturization, integration, and performance enhancement of electronic devices have driven an urgent demand for efficient thermal management. Among which, ultra-high molecular weight polyethylene (UHMWPE) could be considered as a promising candidate due to its inherent high specific strength and theoretically ultra-high intrinsic thermal conductivity, once its chain structure been tailored. However, current methods for preparing intrinsic thermally conductive UHMWPE requires complex post-treatment for the extreme-stretching along machine direction, and can only employed as film and fibers. In this work, we introduce cyclic pulsating pressure (CPP) during the compression molding of UHMWPE, and for the first time, proposed a single-step method for fabricating intrinsic thermally conductive UHMWPE sheet. The evolutions in crystalline structure and molecular chains with different CPP conditions have been comprehensively investigated, and the results suggest that its structural changes with proper selection of the pressure-off period (T_off) in CPP process. Consequently, the as-prepared UHMWPE shows obviously enhancement in its thermal conductivity from 0.619 W/mK for conventional sheet to 3.91 W/mK for the one under CPP with optimized T_off, which is then considered due to the in-plane alignment of crystals. Ultimately, our novel intrinsic thermally conductive UHMWPE sheet was employed to transfer the heat from LED to show its ability as thermal conductive materials. We believe that this work can not only provide a highly thermal conductive polymer sheet with its fabrication protocol, but also supply fundamental insight around the dynamic pressure induced structural evolutions of UHMWPE.