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Polymer Composite Materials Modified with Nano-Oxides and Phosphinates Hybrid Flame Retardant Systems

Unsaturated polyester based composites materials present several improved properties over conventional materials. However, these composites show great sensitivity to high temperatures and poor fire behaviour. In the present study, an effort is undertaken to develop new unsaturated polyester composites with improved fire reaction behaviour by matrix modification with hybrid flame retardant systems based on nanooxides and phosphinates. For this purpose, a series of composite formulations containing different contents and types of both metal oxide nano/micro particles and organic phosphinates were manufactured, with basis on the Taguchi L9 orthogonal array, and tested for fire reaction and mechanical properties. The data treatment was carried out through analyses of variance. Fire reaction properties were analysed and quantified by the vertical flammability test (UL-94), and the mechanical properties were studied by flexural, Shore D, and Charpy impact tests. The results were compared with those obtained for plain resin specimens. Test results revealed that the addition of hybrid flame retardant systems introduced reasonable improvements in at least one fire reaction property. However, it was verified that the filler addition led to a decrease in mechanical properties, probably due to poor matrix-filler adhesion. Further studies are required in order to improve the mix design formulations.