Abstract
The bead foaming behavior of ether- and an ester-based Tensor Processing Unit (TPU) resins were investigated in a lab-scale reactor using supercritical CO2 as the blowing agent. The samples were saturated at various saturation temperatures and the effects of hard segment crystallization during the saturation on the foaming behavior of the TPU samples were explored. The results revealed that the different HS crystallization tendencies and possible CO2 solubility differences in two TPU grades led to their different foaming behaviors. The ester-based TPU could be foamed within a wider saturation temperature range and revealed an easier cell growth and foam expansion while the ether-based TPU showed a more limited cell growth behavior and hence processing window. The effect of pre-annealing and hence the isothermally induced HS crystallization on the foaming behavior of the ether-based TPU and the influence of depressurization rate on the foaming behavior of ester-based TPU was also explored.
Acknowledgements
The authors would like to greatly appreciate the Global Research group of Huntsman Polyurethanes (Huntsman Polyurethanes-Belgium) for kindly supplying the materials and sponsoring the project. We would also like to acknowledge the contributions made by the scientists from Huntsman Polyurethanes, specifically Dr. Rene Klein, Ms. Conny Nijs, and Mr. Giovanni Tomei. The authors would also like to sincerely thank Professor Mustafa Urgen and Professor Kursat Kazmanli from Istanbul Technical University for their support by providing their lab space to run SEM experiments.
Author contribution: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
Research funding: None declared.
Conflict of interest statement: The authors declare no conflicts of interest regarding this article.
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