INVESTIGADORES
FRONTINI patricia Maria
congresos y reuniones científicas
Título:
Fracture of montmorillonite reinforced polypropylene nanocomposites obtained by shear controlled orientation in injection molding
Autor/es:
A. COSTANTINO; V PETTARÍN; PATRICIA FRONTINI; J. VIANA; A. PONTES; A. POUSADA
Lugar:
Ghent
Reunión:
Conferencia; 5th International Conference Polymers Moulds Innovations PMI2012; 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, de-veloping the shear zone into a thicker multilayer zone. XRD analysis showed marked differences in crystalline structure at the core and the surface, being larger in SCORIM in comparison to CIM. Furthermore, the clay appears to be intercalated in the skin and exfoliated in the core of nanocomposites injected parts. Fracture be-havior 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 be-havior while nanocomposites exhibited quasi-stable behavior induced by a large deformation capability of the skin. Despite fracture initiates at practically the same loading levels, overall propagation energy values varied with processing conditions and nanoclay content.