The effect of polypropylene (PP) on the Seebeck coefficient (S) of carbon nanofibers (CNFs) in melt-extruded PP composites filled with up to 5 wt. % of CNFs was analyzed in this study. The as-received CNFs present an electrical conductivity of ~320 S m⁻¹ and an interesting phenomenon of showing negative S-values of −5.5 μVK⁻¹, with 10⁻² µW/mK² as the power factor (PF). In contrast, the PP/CNF composites with 5 wt. % of CNFs showed lower conductivities of ~50 S m⁻¹, less negative S-values of −3.8 μVK⁻¹, and a PF of 7 × 10⁻⁴ µW/mK². In particular, the change in the Seebeck coefficient of the PP/CNF composites is explained by a slight electron donation from the outer layers of the CNFs to the PP molecules, which could reduce the S-values of the as-received CNFs. Our study indicates that even insulating polymers such as PP may have a quantifiable effect on the intrinsic Seebeck coefficient of carbon-based nanostructures, and this fact should also be taken into consideration to tailor conductive polymer composites with the desired thermoelectric (TE) properties.

聚丙烯 (PP) 对碳纳米纤维 (CNF) 塞贝克系数 (S) 的影响，在熔融挤出的 PP 复合材料中填充高达 5 wt. 本研究分析了 CNF 的百分比。原样的 CNF 具有~320 S m ^{-1 的}电导率和显示负 S 值为 -5.5 μVK ^-1的有趣现象，其中功率因数 (PF) 为10 ^-2  μW/mK ²。相比之下，PP/CNF 复合材料的重量为 5。% 的 CNF 显示出较低的电导率，约为 50 S m ^-1，负 S 值为 -3.8 μVK ^-1，PF 为 7 × 10 ^-4  µW/mK ². 特别是，PP/CNF 复合材料的塞贝克系数的变化可以通过从 CNF 的外层向 PP 分子提供轻微的电子来解释，这可能会降低原样的 CNF 的 S 值。我们的研究表明，即使是绝缘聚合物（如 PP）也可能对碳基纳米结构的内在塞贝克系数产生可量化的影响，在定制具有所需热电 (TE) 特性的导电聚合物复合材料时，也应考虑这一事实。