Rigid polyurethane foam (RPUF) is widely used in refrigerators industry due to having extraordinary thermal insulation capacity. Besides possessing high insulation, it is a critically important structural element constituting the skeleton of the refrigerator. Despite these superior features, RPUF tends to have fast flame-spread because of not only their organic structure but also rigid cellular structure. The useful/beneficial approach to reduce the combustion tendency of RPUFs is to use a synergistic flame retardant blends. Moreover, the composite materials are aimed to be preserved both mechanical and thermal insulation properties. In this study, the RPUF composites, blown with cyclopentane/isopentane blends, were prepared by one-shot method. Halogen free flame retardant combinations were incorporated into the foam at different concentrations to investigate the synergism between the additives. The flame retardancy of filled RPUFs were evaluated by Limiting Oxygen Index (LOI), and UL 94 HB tests. Flammability parameters, such as heat release rate, total heat release, smoke production rate and so on were evaluated by cone calorimeter. Significant enhancement of flame retardancy and smoke suppression of the foams was obtained. The thermal conductivity and compressive strength were determined. The insulation and mechanical properties of the composites were improved with respect to the neat RPUF. The cell structure of foams was investigated by using SEM.
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