Microestructura y propiedades mecánicas de compuestos de polipropileno con hidróxido de magnesio y aluminio moldeados por inyección

Resumo

The use of magnesium and aluminium hydroxides as flame retardants for polypropylene is recent although it had an important growth due to the necessity to eliminate traditional halogenated flame retardants. The main advantages of these hydroxides are its complete harmlessness and a considerable smoke suppressant effect. However, content levels up to 60 wt-% are required to get a complete flame retardancy. Such mineral filler concentrations can provoke important changes of the mechanical behaviour and of the fracture resistance of polypropylene. For this reason, it is necessary to identify the mechanisms of deformation and fracture implicated for this kind of material. The aim of the present work is to contribute to the knowledge of the microstructure and of the mechanisms of deformation and fracture of compounds of polypropylene filled with magnesium and aluminium hydroxides, prepared by injection-moulding. Special attention is paid on the influence of mineral filler content, the particles morphology and its superficial coating kindness. Another objective of this work is to contribute to the development of the load normalization method as a valid tool for the characterization of the fracture behaviour of mineral filled polypropylene.