With advances in fexible and wearable device technology, thermal regulation will become increasingly important. Fabrics and substrates used for such applications will be required to efectively spread any heat generated in the devices to ensure user comfort and safety, while also preventing overheating of the electronic components. Commercial fabrics consisting of ultra-high molecular weight polyethylene (UHMW-PE) fbers are currently used in personal body armor and sports gear owing to their high strength, durability, and abrasion resistance. In addition to superior mechanical properties, UHMW-PE fbers exhibit very high axial thermal conductivity due to a high degree of polymer chain orientation. However, these materials have not been widely explored for thermal management applications in fexible and wearable devices. Assessment of their suitability for such applications requires characterization of the thermal and mechanical properties of UHMW-PE in the fabric form that will ultimately be used to construct heat spreading materials. Here, we use advanced techniques to characterize the thermal and mechanical properties of UHMW-PE fabrics, as well as other conventional fexible materials and fabrics. An infrared microscopy-based approach measures the efective in-plane thermal conductivity, while an ASTM-based bend testing method quantifes the bending stifness. We also characterize the efective thermal behavior of fabrics when subjected to creasing and thermal annealing to assess their reliability for relevant practical engineering applications. Fabrics consisting of UHMW-PE fbers have signifcantly higher thermal conductivities than the benchmark conventional materials while possessing good mechanical fexibility, thereby showcasing great potential as substrates for fexible and wearable heat spreading application.

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A.A. Candadai, E.J. Nadler, J.S. Burke, J.A. Weibel, A.M. Marconnet, Thermal and mechanical characterization of high-performance polymer fabrics for applications in wearable devices, Scientific Reports, Vol. 11, 8705, 2021.