Heat Transfer in Polymer Composites Filled with Inorganic Hollow Micro-Spheres

Abstract

The advances in studies on the heat transfer in polymer composites filled with inorganic hollow microsphere were reviewed, and the heat transfer process and mechanisms in the polymer/inorganic hollow microsphere composites was described in this chapter. On the basis of the law of minimal thermal resistance and the equal law of the specific equivalent thermal conductivity, a theoretical model of heat transfer in polymer/inorganic hollow micro-sphere composites was established and the corresponding equation of effective thermal conductivity was derived. The simulation of the heat transfer in the polymer/inorganic hollow microsphere composites was made by means of a finite element method. The measurement instrument and methodology of the effective thermal conductivity of the polymer/inorganic hollow microsphere composites were introduced, and the effective thermal conductivity (k _eff) of polypropylene composites filled with hollow glass bead (HGB) was measured. It was found that the effective thermal conductivity decreased linearly with an addition of the volume fraction (φ_f) of the beads. The simulated keff of the PP/HGB composites decreases also as a linear function with an increase of φ _f, and are roughly close to the experimental measured data, the k _eff with a 3D model are higher than those with a 2D model, and the difference between them increases with an increase of φ _f. Moreover, good agreement was showed between the measurements from the PP/HGB composites within the φ _f range from 0 to 20 % and the theoretical predictions by means of this equation.