Thermal conductivity of PP/Al(OH)3/Mg(OH)2 composites

Polypropylene (PP) composites filled with aluminum hydroxide (Al(OH)3) and magnesium hydroxide (Mg(OH)2) were prepared using a twin-screw extruder. The effective thermal conductivity (keff) of the composites was measured by means of a thermal conductivity instrument under different testing temperatures. The results showed that the values of keff increased quickly with an increase the volume fraction (ϕf) of Al(OH)3/Mg(OH)2 powder when ϕf was less than 7.1%, then keff increased slightly as ϕf was varying from 7.1% to 13.3%, while the values of keff increased obviously when ϕf was more than 13.3%. Under the same conditions, the values of keff increased nonlinearly with increasing the diameter (d) of the Al(OH)3/Mg(OH)2 powder. The values of keff of the composites increased somewhat with a rise of test temperature. On the basis of the experimental results, the thermal conduction mechanisms of the composite were analyzed and discussed.