UNDERSTANDING FOAMING MECHANISMS
Foaming is a complicated phenomenon in which a significant number of mechanisms play a key role. Nucleation, growing, degeneration mechanisms (coalescence, coarsening, drainage) and stabilization of the cellular structure occur in every foaming process but the way they take place depend on the foaming technology used, the formulation and the processing parameters. In addition, most foaming processes can be considered as “black boxes”, this means that you know the formulation and the processing parameters used and you can characterize the final foam obtained, but there is no experimental information about how the cellular structure and density of the foam are developed. Having a proper understanding of how foaming mechanisms behave in each process is very helpful to develop foams with tailored cellular structures and properties.
PART 2 – EVALUATION OF THE FOAMABILITY AND ITS RELEVANCE IN DIFFERENT FOAMING PROCESSES
SPEAKER: ESTER LAGUNA-GUTIERREZ
In this second part of the webinar, we focus on explaining how we predict the foamability of thermoplastic polymers by using rheological techniques and by characterizing the intrinsic thermal properties of the polymer matrices.
We explain how we perform shear rheological tests, extensional rheological tests and differential calorimetry tests to obtain key parameters for foaming such as the zero-shear viscosity, the strain hardening or the crystallization temperature and how these parameters are used to understand the final density and cellular structure of complex polymeric systems like polymer blends, polymer composites, recycled polymers, etc.
We have been working with this approach for more than years and we have found a straightforward way to correlate the final foam characteristics with the properties of the initial formulation used for foaming.
Several case studies explaining how this information can be useful in real industrial environments are also included.