Thermal conductivity of PTFE composites with three-dimensional randomly distributed fillers

Aiming at the optimal design of physical properties of polytetrafluoroethylene (PTFE) composites with random three-dimensional (3-D) fillers, the present paper studies the thermal conductivity of PTFE composites reinforced with single-phase and two-phase reinforcements (particles and fibers), respectively by the use of 3-D finite element simulations. To improve the accuracy, the random distribution of the sizes and locations of particles is taken into account. It is found that there exists a filler to matrix saturation conductivity ratio at a certain volume fraction in the PTFE composites with particle reinforcement above which the conductivity does not increase. The filling of carbon fibers, with the initial purpose of improving the mechanical properties of PTFE composites plays an important role in the improvement of the conductivity performance of the multiphase PTFE composites. Compared with single-phase filler composites, it is seen that the saturation point moves forward in the PTFE composites with both graphite particles and fibers.