Influence of the presence and amount of metal nanoparticles on the thermal and mechanical properties of iPP/soft paraffin wax phase change materials for thermal energy storage
Molaba, Mamohanoe Patricia
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Nanocomposites based on iPP and an iPP/wax phase change blend with Ag nanoparticles were studied. The aim of this study was to correlate the thermal and electrical conductivity, as well as dynamic mechanical properties, with the morphology of the samples prepared using quenching in ice water and slow cooling from the melt, as well as different nanoparticle contents. Morphological analysis of the iPP/Ag nanocomposites showed that the Ag particles were well dispersed in the polymer, and formed nucleation centres for the crystallization of iPP. In the iPP/wax/Ag nanocomposites they were also well dispersed, but in the wax phase in between the iPP spherulites. The extent of filler agglomeration increased with increasing filler contents in both iPP and the iPP/wax blend. The Ag particles, whether in the iPP or wax phase, had little influence on the crystallinities and melting temperatures of iPP samples, even at higher filler contents. The presence Ag particles in iPP had little influence on the modulus of the iPP, but the presence of both wax and Ag particles significantly improved the modulus of these phase change nanocomposites. The thermal and electrical conductivities of the samples more significantly improved when both wax and Ag were present. With increasing Ag particle contents in both iPP/Ag and iPP/wax/Ag, the thermal conductivities increased, but leveled off at higher filler contents, while the electrical conductivities continuously increased with increasing filler contents. The slowly cooled samples had higher crystallinities than the quenched samples and therefore the slowly cooled samples were more thermally conductive than the quenched samples.