Influence of Alumina Content and Thermal Treatment on the Thermal Conductivity of UPE/Al2O3 Composite

Ultra high molecular weight polyethylene/alumina (UPE/Al2O3) microcomposites with high loading micro alumina (Al2O3, 20 to 100 phr) were prepared by casting method. The composites were thermal treated (cooled slowly) and then the thermal properties were studied at temperatures from 25 to 125 degrees C. Thermogravimetric analysis (TGA) and scanning electron microscopic (SEM) proves the homodispersion of Al2O3 microparticles in UPE. TGA indicates that the temperature of 5% weight loss of UPE/Al2O3 (100 phr) composite is 467.0 degrees C, 10.5 degrees C higher than that of pure UPE. Differential scanning calorimetry (DSC) shows that the melting point and the real degree of crystal (X-rc) of treated UPE/Al2O3 composite (100 phr) are 141.4 degrees C and 65.7%, respectively, all higher than that of untreated composite, which can be described by crystal bridge mechanism. The density of the composite is also be enhanced because of crystal volume shrinkage induced by thermal treatment. The thermal conductivity of the treated UPE/Al2O3 composite (100 phr) is 1.920 W (m K)(-1) at 25 degrees C, 23.6% higher than that of the untreated composite. Crystal bridge thermal conduction mechanism is proposed. The thermal conductivity of UPE/Al2O3 composite has some dependency on the increasing Al2O3 content and also thermal treatment. These results can give some advice to design formulations for practical applications in pipe area and other wear area. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40528.