INTEMA   05428
INSTITUTO DE INVESTIGACIONES EN CIENCIA Y TECNOLOGIA DE MATERIALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Shear controlled orientation in injection moulded PP/nanoclay pieces: microstructure, fracture and thermal performance
Autor/es:
MARIA ALEJANDRA COSTANTINO; VALERIA PETTARIN; PATRICIA FRONTINI; JULIO VIANA; ANTONIO PONTES; ANTONIO POUZADA
Lugar:
Aveiro
Reunión:
Conferencia; ICPB5 - 5th International Conference on Polymer Behavior; 2012
Resumen:
In this work, a nanoclay based masterbatch is mixed with polypropylene and direct injection molded by conventional and SCORIM techniques. In SCORIM, two extreme shear levels are applied by changing processing conditions (melt temperature and shear time). We assess therefore the effect of high shear conditions in the levels of intercalation/exfoliation and orientation of the nanoclay in the polymer matrix and in the mechanical properties of the nanocomposite. Previous works showed that Morphology developed during SCORIM results very different from the one of CIM, as seen by PLM and DSC, also avoiding the shrinkage produced in conventional injected thick parts. Addition of nanoclay diversifies the morphology, developing the shear zone into a thicker multilayer zone. XRD analy-sis showed marked differences in crystalline structure at the core and the surface, being larger in SCORIM in com-parison to CIM. Furthermore, the clay appears to be intercalated in the skin and exfoliated in the core of nanocompo-sites injected parts. No significant differences in thermal degradation were found between CIM and SCORIM. Regarding DMA analysis it was found that the morphology induced by melt manipulation during SCORIM futher increased HDT. Fracture behavior is also 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 condition. Neat PP showed non linear brittle behavior while nanocomposites exhibited quasi-stable behavior induced by a large deformation ca-pability of the skin. Despite fracture initiates at practically the same loading levels, overall propagation energy values varied with processing conditions and nanoclay content.