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- Conflict of Interest
- In relation to this article, we declare that there is no conflict of interest.
- Publication history
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Received May 31, 2024
Accepted July 12, 2024
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This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/bync/3.0) which permits
unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
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Investigating the Foaming Process of a Thermoplastic Elastomer (TPE) Using Rheology and Image Analysis
Abstract
This study introduced a method to simultaneously characterize time-resolved rheological and volumetric changes occurring
during the foaming process of a thermoplastic elastomer containing an encapsulated physical blowing agent. For this, a
conventional rotational rheometer was equipped with a commercial digital camera to capture video recordings. These video
recordings were digitized into volumetric data using custom-written computer-vision-based algorithm. We fi rst investigated
rheological and volumetric changes during temperature ramp tests. The calculated cell volume fractions varied quantitatively
depending on cell expansion and shrinkage. The viscoelastic moduli followed the characteristic behavior of the cell volume
fraction. Furthermore, to analyze the volumetric changes under hypothetical processing conditions, a four-stage protocol
comprising time sweep and temperature ramp was designed. The results revealed that the cell shrinkage induced by internal
gas permeation at high temperatures was signifi cantly greater than that induced by internal pressure reduction during cooling.
Finally, comparison between foam densities computed using our algorithm and those measured using a densimeter revealed
good agreement within 3% relative error. This demonstrates the applicability of our algorithm for quantitatively assessing
volumetric changes of foam.
