Polyurethane foams are by far the most popular cellular polymers as they cover more than the half of the total foams market. Depending on if they are either rigid or flexible they are mainly employed as thermal insulators (rigid polyurethane foams) or for comfort related applications (mattresses, seats) in the case of flexible foams. The production of polyurethane foams is based on the reactive mixing of polyol and isocyanate. The comprehension of all the aspects related with the formation and performance of these materials is far to be simple and it motivated the creation of this research topic in CellMat Laboratory.
CellMat Laboratory works in the different aspects involved in the production, characterization and modelling of polyurethane (either rigid or flexible) foams. A methodology based on the combination of in-situ (X-ray radioscopy and FTIR) and ex-situ (tomography and scanning electron microscopy) experimental techniques has been extremely helpful to disentangle the complex reactions and processes occurring during the formation of this kind of foams. The analysis of the reaction kinetics and the characterization of the structure and the properties of polyurethane foams has been the basis to develop formulations with tailored characteristics. In the frame of this research line, the covered topics are the following:
- Using in-situ FTIR spectroscopy to follow the formation process kinetics: Splitting and quantification of the different reactions taking place.
- Employment of non-conventional in-situ techniques such as X-ray radioscopy and tomography: Evaluation of the foaming mechanisms and advanced characterization of the structure.
- Characterization and modelling of the thermal properties. Correlation with the chemical composition and the cellular structure. Determination of the extinction coefficient.
- Development of PU foams with reduced thermal conductivity and improved mechanical properties.
Example of the foaming process of a rigid PU foam followed by in-situ FTIR
Modelling the thermal conductivity of polymeric foams