Corrosion, erosion, and fouling by scale deposition are detrimental to heat‐exchanger tube at geothermal binary‐cycle power plants. In this work, polytetrafluoroethylene was blended in a polyphenylenesulfide matrix with different concentrations of multiwall carbon nanotube (MWNT) using the melt‐mixed method to reduce scale deposition on the metal surface. The prepared nanocomposites with different concentrations of MWNT were characterized by various properties such as morphology, hydrophobicity, electrical, thermal, and rheological properties. The morphology of nanocomposite was changed from smooth to nano‐pin‐like with the addition of MWNT. The varied concentration of MWNT led to differing hydrophobicity of nanocomposite. Increasing the loaded amount of MWNT in the nanocomposite led to decreased electrical resistivity up to 3.1 × 103 Ω cm because of percolation of the MWNT in the polymer matrix. In addition, we investigated the enhancement of thermal performance (10% of lower crystallization peak) of the prepared nanocomposite. These performance results indicate that the prepared nanocomposite can be widely adopted for use in high‐performance heat exchangers in geothermal industries.