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The effect of distinct morphologies induced by shear controlled orientation in injection moulding (SCORIM) in the mechanical and fracture performance of polypropylene (PP) and PP/nanoclay mouldings is examined in this work. The effect of high shear conditions applied during processing was assessed. Samples exhibited a range of fracture stability ranging from a modest non-linearity to a quasi-stable regime depending on material type and injection conditions. Neat PP showed non-linear brittle behaviour while nanocomposites exhibited quasi-stable behaviour induced by the large deformation capability of the skin layer. Despite the fracture initiating at practically the same loading levels, the propagation energy varied with processing conditions and nanoclay content. The reduction of the core layer achieved by the SCORIM processing along with the differences between the skin and core favoured by the presence of nanoclay are responsible for the toughening of the SCORIM PP/nanoclay thick mouldings. [ABSTRACT FROM AUTHOR]

The use of nano-scaled reinforcements enchances the mechanical performance of the resulting material and the addition of natural origin nanotubes improve the sustainability and environmental impact of the product. The present work describes the preparation, characterization and processing of nanocomposites based on thermoplastic Polyamide 6 and Halloysite nanotubes (HNT). The nanocomposites were prepared in several stages and the results ensure the final application at "industrial scale". The first formulation was a high concentration of Halloysite nanotubes (up to 30% weight content) made with a twin screw extrusion compounder which was used as a masterbatch. Application materials were obtained reducing the masterbatch in raw PA 6 down to 3 or 6% of HNTs weight content. In this stage the influence of use or not an extruder-compounder was analyzed. Finally, a low cost preparation and sustainable development technique as injection moulding was applied to obtain test parts of all developed materials. Results were analyzed at a microscopic scale (TGA, FTIR, XRD, SEM, TEM) and macroscopic scale (rheology, mechanical properties and flame resistance). TGA and FTIR results show that the content of HNTs was as accurate as expected. XRD results showed a greater interaction between the HNTs and the matrix if the extrusion-compounding process was used before injection moulding. SEM and TEM results showed a better dispersion of HNTs if extrusion was performed at high screw rotation speed. All analysis concluded the nanocomposites can be processed on standard equipment due to the resultant low viscosity. Also, low content of HNTs proved that mechanical properties are highly improved as flame resistance remains equivalent. [ABSTRACT FROM AUTHOR]