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 (φf) 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.