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Oral Poster Presentation

The effect of elastomer viscosity in pp/poe foams produced by core-back injection moulding over impact properties

Wednesday (07.10.2020)
18:52 - 18:55

Polypropylene (PP) is a polymer with excellent properties such as easy processability, good stiffness and strength, high thermal stability and excellent chemical resistance, but with low ductility [1] especially when it is foamed [2,3]. In the case of PP compounds, ductile solids become brittle foams even for very low expansion ratios. Thus the objective of this work is to implement different strategies allowing improving the ductility of PP based foams with low expansion ratio avoiding the ductile to brittle transition when the material is foamed.


There are several strategies to improve the impact response of foams. One strategy is to enhance the impact behavior of the PP matrix by producing blends with impact modifiers as elastomers. This is known as elastomer toughening [4]. Poly(Styrene–Ethylene–Butylene–Styrene) (SEBS) [5], Ethylene-Propylene Rubber (EPR) [6] and Ethylene Propylene–Diene Monomer elastomer (EPDM) [7] are adequate elastomer to blend with PP that provide good results. But some of the most promising materials nowadays are ethylene/α-olefin copolymers, and especially, Octene-Ethylene copolymers (POE) [8]. Despite the success in toughening achieving with these blends, it is not well understood the relation between the viscosity of the dispersed phase and the impact behavior of the foamed materials.


The other possible strategy to improve the impact behavior is to produce foams with an improved cellular structure [3]. Core-back injection molding foaming allows obtaining finer cellular structures than low pressure foaming [9] and due to this, it has been the production route used in the research. As far as the authors know, the impact response of PP/POE foams produced by core-back injection molding foaming has not been studied yet.


Solids and foams with different density reductions were produced using PP/POE blends with POE of different viscosity. Impact properties were tested by Instrumented Falling Weight Impact (IFWI). The relation between phases, studied by rheological (figure 1) and calorimetric techniques, was crucial to understand the mechanical behavior of the produced materials.

Ph.D. Santiago Muñoz Pascual
University of Valladolid
Additional Authors:
  • Dr. Cristina Saiz-Arroyo
    Cellmat Technologies S.L.
  • Dr. Anja Vananroye
    KU Leuven
  • Prof. Dr. Paula Moldenaers
    KU Leuven
  • Prof. Dr. Miguel Angel Rodriguez-Perez
    University of Valladolid


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