Fracture behaviour of PP-nanoclay composites processed by Shear Controlled Injection moulding

A. COSTANTINO; V PETTARÍN; PATRICIA FRONTINI; J. VIANA; A. PONTES; A. POUSADA

AVEIRO

Conferencia; 5th International Conference on Polymer Behavior; 2012

In this work, a nanoclay based masterbatch is mixed with polypropylene and direct injection molded by conventional and SCORIM techniques. The effect of high shear conditions in the levels of ntercalation/exfoliation and orientation of the nanoclay in the polymer matrix and in the mechanical properties of the nanocomposite was assessed. 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 analysis showed marked differences in crystalline structure at the core and the surface, being larger in SCORIM in comparison to CIM. No significant differences in thermal degradation were found between CIM and SCORIM. 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 capability of the skin. Despite fracture initiates at practically the same loading levels, propagation energy values varied with processing conditions and nanoclay content.