Abstract:

The heat transfer mechanism of the polymer composites filled with hollow micro.spheres is analyzed in this paper.It is argued that heat transfer mainly includes the thermal conduction between the solid and the gas,the thermal radiation among the hollow micro-sphere surfaces.and the natural therm al convection of the gas in the hollow mi.cro.spheres.Th en.a theoretical model of the heat transfer in the composites is established based on the laws of the minimal thermal resistance and the specific equivalent therm al conductivity.An equation for the equivalent therm al conductivity(k_eff)is derived,by which the equivalent thermal conductivity of the polypropylene composites filledth hollow mi cro.spheres is estimated.Th e obtained results are finally compared with the numerically simulated ones.It is concluded that the estimated equivalent thermal conductivity is of the salne variation as the simulated one at a lower filler content(φ _f≤20%,volume fraction),and that the equivalent thermal conductivity linearly decreases with the increase of the filler content as well as with the increase of the filler size at a constant filler content.

Key words: hollow micro-sphere, polymer composite, heat transfer model, therm al conductivity