# Characterization and Modeling of Microcellular HDPE Foams Processed by MuCell Injection Molding with Supercritical Nitrogen: Process-Microstructure-Property Relationship

Achref Elhasni, Mohamed Yousfi, Jannick Duchet-Rumeau, Abderrahim Maazouz

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To cite this version:

Achref Elhasni, Mohamed Yousfi, Jannick Duchet-Rumeau, Abderrahim Maazouz. Characterization and Modeling of Microcellular HDPE Foams Processed by MuCell Injection Molding with Supercritical Nitrogen: Process-Microstructure-Property Relationship. 26e Congrès Français de Mécanique, Aug 2025, Metz, France. hal-05079985

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https://hal.science/hal-05079985v1

Submitted on 22 May 2025

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Distributed under a Creative Commons Attribution 4.0 International License
Characterization and Modeling of Microcellular HDPE Foams
Processed by MuCell Injection Molding with Supercritical Nitrogen:
Process-Microstructure-Property Relationship

Achref ElHasni¹, Mohamed Yousfi¹*, Jannick Duchet-Rumeau¹,
Abderrahim Maazouz¹,²

¹Université de Lyon, CNRS, UMR 5223, Ingénierie des Matériaux Polymères, Université
Claude Bernard Lyon 1, INSA Lyon, Université Jean Monnet, F-69621 Villeurbanne
Cedex, France

²Hassan II Academy of Science and Technology, Rabat, Morocco

Corresponding author: mohamed.yousfi@insa-lyon.fr

**Abstract:**

The demand for lightweight materials with enhanced properties has driven research into innovative manufacturing techniques. This study explores a novel approach to elaborate microcellular high-density polyethylene (HDPE) foams using the MuCell injection molding process. HDPE foams with a controlled microcellular structure were successfully produced, using supercritical nitrogen (Sc. N2) as a blowing agent. Our research focused on the influence of key process parameters on the cellular morphology and mechanical properties of molded parts. The main variables studied included mold temperature, (Sc. N2) content, screw velocity, and injection rate. Comprehensive characterization of the foams was carried out using various analytical techniques, including rheological and thermal measurements under pressure, as well as physicochemical analyses of the polymer/supercritical fluid mixture (i.e. surface tension at high supercritical conditions, melt density by the Magnetic Suspension Balance (MSB), and solubility of Sc. N2 in HDPE by Sieverts method. The impact of MuCell injection molding conditions on cell diameter, cell density, Young's modulus and creep behavior through conventional and Taguchi experimental designs was systematically evaluated. In addition, numerical simulation was implemented to predict the effect of process parameters on morphology and weight reduction of model rectangular HDPE parts based on the modified Han and Yoo theory. The numerical results were compared with experimental data, allowing for a critical validation of the developed methodology. This study makes a significant contribution to understanding the microcellular foaming process of HDPE and opens new perspectives for the development of lightweight materials with enhanced physical properties, suitable for large-scale industrial production.

**Keywords:** Supercritical nitrogen, microcellular foams, MuCell injection molding, experimental design, morphology, mechanical properties, numerical simulation.