Thermal conductivity of micro/nano-porous polymers: Prediction models and applications

Micro/nano porous polymeric material is considered a unique industrial\nmaterial due to its extremely low thermal conductivity, low density, and high\nsurface area. Therefore, it is necessary to establish an accurate thermal\nconductivity prediction model suiting their applicable conditions and provide a\ntheoretical basis for expanding of their applications. In this work, the\ndevelopment of the calculation model of equivalent thermal conductivity of\nmicro/nano porous polymeric materials in recent years was summarized. Firstly,\nit reviews the process of establishing the overall equivalent thermal\nconductivity calculation model for micro/nano porous polymers. Then, the\npredicted calculation models of thermal conductivity are introduced according\nto the conductive thermal conductivity models and the radiative thermal\nconductivity models separately. In addition, the thermal conduction part is\ndivided into the gaseous thermal conductivity model, solid thermal conductivity\nmodel and gas-solid coupling model. Finally, it is concluded that, compared\nwith other porous materials, there are few studies on heat transfer of\nmicro/nano porous polymers, especially on the special heat transfer mechanisms\nsuch as scale effects at the micro/nanoscale. In particular, the following\naspects of porous polymers still need to be further studied: micro scaled\nthermal radiation, heat transfer characteristics of special morphologies at the\nnanoscale, heat transfer mechanism and impact factors of micro/nano porous\npolymers. Such studies would provide a more accurate prediction of thermal\nconductivity and a wider application in energy conversion and storage systems.\n