The influence of the processing and the alumina synthesized in laboratory on the polypropylene (PP) properties

This work aimed to evaluate the influence of the processing and the alumina synthesized in laboratory alumina on the polypropylene (PP) properties. The injected PP (PPi), the extruded and injected PP (PPei) and the composite (PP / Al-5pcr), were characterized. The XRD results showed that alumina has a crystalline structure of the corundum type and that it did not alter the crystalline structure of the PP, but it reduced the degree of crystallinity, whereas the processing made the PP more crystalline. The thermal transitions, Tm and Tc of the PP were practically unchanged by processing and alumina. In the mechanical properties, the impact strength was altered by the processing. For the composite, there was increase of the elastic modulus and reduction in tensile and impact strength. In the flammability test, the processing accelerated the burning process and the alumina slowed when compared to the PP. In the rheological analysis all the systems presented pseudoplastic behavior. The viscosity of the PP was reduced with the processing and the presence of the alumina, characterizing degradation. (author)