In-depth radiative heat transmittance through polypropylene/nanoclay composites

In-depth heat absorption and material physical properties (thermal conductivity, melting temperature, melt viscosity etc) control the temperature profile across the thickness of a polymer specimen under external irradiance. In this work, the effect of nanoclays on the in-depth heat absorption is studied measuring the transmitted heat flux through a thin layer of material. Results showed that nanoclays reduce the heat transmitted through the composites, which is explained by the additional infrared absorbance of the nanoclays themselves and scattering. Transmitted heat was measured as a function of time, revealing different trends for the different compositions. In particular, the formation of bubbles in the range of 100 mu m was observed in the presence of sodium montmorillonite and proved to be related to moisture release during the early stage of irradiation from the external heat source. The presence of such bubbles may scatter infrared radiation, resulting into a lower heat transmittance through the material. (C) 2013 Elsevier Ltd. All rights reserved.