Augusto Peres

Comparison of bismuth trioxide and antimony trioxide as synergists with decabromodiphenyl ether in flame retardancy of high-impact polystyrene

Flame-retardant additives used in plastics are based on halogen, phosphorus, inorganic compounds, and minerals. In this study, the use of bismuth trioxide as synergistic agent with brominated flame retardant is investigated and compared to formulations with antimony trioxide. Decabromodiphenyl ether and metal trioxide were incorporated in a polymer matrix via single-screw extrusion. The samples were classified with the UL 94 vertical burning protocol and studied with thermogravimetric analysis. The general combustion and heat release behaviors were studied via cone calorimeter. Results showed that 4% (wt) Bi2O3 displayed a synergistic effect with 12% (wt) of the halogen compound to achieve V-0.

Mixing process influence on thermal and rheological properties of NBR/SiO2 from rice husk ash

Silica was extracted from rice husk ash (RHA) by a sequence of reactions to produce nanosilica. Two laboratory routes, co-coagulation and spray drying, were used to incorporate the nanosilica into the rubber matrix. Samples were characterized regarding filler incorporation efficiency, thermal stability, rheological behavior and morphology. Thermogravimetric analysis showed that spray-drying was the most efficient filler incorporation process and also the presence of silica increased the thermal resistance of the rubber compound when compared to the unfilled rubber. The rheological behavior showed that NBR filled with silica presented higher elastic torque (S’), storage modulus (G’) and complex viscosity (η*) than unfilled rubber. The Payne effect was also observed for the composites produced by spray-drying. In addition, the thermal behavior and Payne effect results were supported by the comparison of morphology observed by FEG-SEM analysis.