Expanded graphite (EG) is a well-known carbon derivative and widely used as the thermally conductive enhancer for thermal management composites. However, the investigation on thermal conductivity measurement of an individual EG particle is still unexploited, which prevents the exploration of the coupling mechanism between EG and matrices and further measures for thermal conductivity enhancement. Herein, using a variable-length T-type method, we measure the thermal conductivity of an individual expanded graphite ribbon (EGR) obtained by mechanically compressing a separate EG particle. The EGR has a micrometer-sized thickness and a millimeter-sized length. By changing the sample length while maintaining the contact junction, we simultaneously obtained the thermal conductivity of the EGR and the thermal contact resistance between the sample and the probe. The longitudinal thermal conductivity of the EGR reaches up to 335.6±27.4 W m⁻¹ K⁻¹ at room temperature and decreases to 254.8±20.8 W m⁻¹ K⁻¹ as the temperature rises from 300 K to 380 K. With a higher thermal conductivity than most graphene paper products and some carbon fibers, this low-cost nanocarbon-based material exhibits a great advantage in the development of thermally conductive composites, and the presented accurate thermal conductivity provides indispensable data for the rational design of composites.

膨胀石墨（EG）是一种众所周知的碳衍生物，被广泛用作热管理复合材料的导热增强剂。然而，关于单个EG颗粒的热导率测量的研究仍未进行，这阻止了对EG与基体之间的偶联机理的探索以及进一步提高热导率的措施。在本文中，我们使用可变长度T型方法，测量通过机械压缩单独的EG颗粒而获得的单个膨胀石墨带（EGR）的热导率。EGR具有微米尺寸的厚度和毫米尺寸的长度。通过在保持接触结的同时改变样品长度，我们同时获得了EGR的热导率和样品与探头之间的热接触电阻。EGR的纵向热导率高达335.6±27.4 W m^-1 ķ ^-1在室温和降低至254.8±20.8脉冲W M ^-1 ķ ^-1随着温度从300K升高到380 K.随着更高的导热率比大多数石墨烯纸制品和一些碳纤维，这种低成本低廉的纳米碳基材料在导热复合材料的开发中显示出巨大优势，并且所提供的精确导热系数为复合材料的合理设计提供了必不可少的数据。