Morphology-performance relationship of injected polypropylene nano, micro and hybrid composites as assessed by fracture mechanics

MARIA ALEJANDRA COSTANTINO; CAREN ROSALES; VALERIA PETTARIN

Granada

Conferencia; 27th Annual International Conference on Composites or Nano Engineering ICCE-27; 2019

Morphology of semicrystallinepolymersand their composites is a crucial feature that affects thermal and mechanical performance of manufactured parts. Many industrial parts are processed by injection molding which in turn affects the morphology of melt-crystallized polymers. Polypropylene (PP) performance ?in particular? depends mainly on its morphology and crystallinity; and injection molding affects both morphology and crystallinity. In injection molding, the complex thermomechanical conditions to which is subjected the molten polymer induces a gradual and hierarchical variation of morphology, which evolves through the spatial domain of the piece. Besides, the understanding of the fracture, microvoide formation and mechanics of composites and blends is crucial for engineers. In many cases mechanical performance is evaluated by means of conventional mechanical tests such as tensile, flexural or non instrumented impact tests, which are not representative of actual loading situations. In their desire to characterize toughness of ductile polymers, many researchers have turned to fracture tests that imply severe loading conditions, i.e., load triaxiality, being more adequate to evaluate mechanical integrity of final pieces.In this work, the relationship between processing and performance is reviewed for different injected PP pieces: nano, micro, and hybrid composites. Mechanical performance of pieces was evaluated by means of quasi-static fracture tests. The effects of the molding process and of the filler on the microstructure and fracture properties of the polymer composites are summarized.