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    Blast furnace slag or fly ash filled rigid polyurethane composite foams: A comprehensive investigation
    (Wiley, 2019) Akkoyun, Meral; Akkoyun, Serife
    Ground granulated blast furnace slag (BFS) and fly ash (FA) are iron-making industry and power plant byproducts, respectively. Although their use in concrete is quite common, investigation of the effects of these inorganic compounds on polymer properties is quite new, and their use as fillers in polymer foam composites has not yet been really explored. Their properties, such as high electrical resistivity, make them a good asset for use in rigid polyurethane foams that are widely used for insulation. In this study, a comprehensive investigation of the effect of BFS and FA on morphology, electrical and thermal conductivity, and rheological and mechanical properties of water-blown rigid polyurethane foams was performed. The relationship between these properties was examined. A relative enhancement of the properties is observed for filled foams, especially up to the percolation threshold. The results highlight a noticeable effect of the electrical percolation threshold on the different properties of foams. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47433.
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    Improvement of thermal conductivity of rigid polyurethane foams with aluminum nitride filler
    (Sage Publications Ltd, 2021) Akkoyun, Serife; Akkoyun, Meral
    The aim of this work is the fabrication of electrically insulating composite rigid polyurethane foams with improved thermal conductivity. Therefore, this study is focused on the effect of aluminum nitride (AIN) on the thermal and electrical conductivities of rigid polyurethane foams. For this purpose, aluminum nitride/rigid polyurethane composite foams were prepared using a three-step procedure. The electrical and thermal conductivities of the foams were characterized. The thermal transitions, mechanical properties and morphology of the foams were also examined. The results reveal that AIN induces an increase of the thermal conductivity of rigid polyurethane foam of 24% which seems to be a relatively noticeable increase in polymeric foams. The low electrical conductivity of the foams is preserved.