Effect of chain structure on the thermal conductivity of expanded graphite/polymer composites

The thermal conductivity of expanded graphite (EG)/polymer composites is investigated in terms of polymer chain structures. The EG/polyphenylene sulfide (PPS) composite with a backbone of benzene rings shows the continuous highest thermal conductivity and the fastest rate of enhanced ratio at the same content. Then it is followed by EG/syndiotactic polystyrene (sPS) composites with side groups of regularly arranged benzene rings. The last are the EG/amorphous polystyrene (aPS) composites with side groups of randomly arranged benzene rings. Our results show that the chain structures of polymer matrices have a great influence on the interaction and crystallization of EG/polymer composites, which leads to the different thermal behavior. More precisely, the strong p-p interaction between EG and polymer, the nucleation of crystal at the interface of EG/polymer and the relatively rich EG content in the amorphous phase are benefits to the enhancement of thermal conductivity. These factors are proved to be extremely important for the design of high thermally conductive composites in the fields of science and engineering.