The fiber with higher thermal conductivity is rare and it is difficult to measure the thermal conductivity of a single fiber. In this paper, the composite samples of ultra-high molecular weight polyethylene (UHMWPE) fiber and epoxy resin were prepared in order to study the heat conducting properties of the UHMWPE fiber. The specific heat capacity and thermal conductivity of the samples were tested by the transient plane source method. Based on the serial–parallel equivalence theory model, the axial and radial thermal conductivities of the UHMWPE filament were calculated. Effects of the volume fraction of fiber, fineness and drawing ratio on thermal conductivity were explored. Also, the relationship between the structure and thermal conductive capacity was revealed. The results showed that the volume fraction of fibers should be large to obtain a relative accurate value. Moreover, the difference in fineness led to different thermal conductivity of the UHMWPE fiber, the cruder the fiber, the higher the thermal conductivity. Besides, as the drawing ratio increased, the crystallinity and orientation of the fibers also increased. Thus, the results were that the axial equivalent thermal conductivity of the filament was dramatically increased, while the radial equivalent thermal conductivity grew a little. The paper showed that UHMWPE fibers had much higher thermal conductivity than other fibers, and also provided a new method to get the thermal conductivity of UHMWPE single fiber.
