Polymer Supercritical CO₂ Foaming under Peculiar Conditions: Laser and Ultrasound Implementation

Area of Science:

• Materials Science
• Polymer Processing
• Chemical Engineering

Background:

• Supercritical CO2 foaming is a versatile polymer processing technique.
• Out-of-autoclave methods offer advantages over traditional approaches.
• Investigating novel assistance methods is crucial for process optimization.

Purpose of the Study:

• To investigate the use of laser and ultrasound (US) as out-of-autoclave assistance technologies for supercritical CO2 batch foaming.
• To evaluate the effect of US on the cellular morphology and thermal conductivity of PMMA samples.
• To explore the potential of these methods for creating micro-porous polymer structures.

Main Methods:

• Two-step batch foaming process using supercritical CO2.
• Assistance provided by laser and ultrasound (US) technologies.
• Foaming of bulk thick polymethyl methacrylate (PMMA) samples.
• Analysis of cellular morphology, porosity, and thermal conductivity.

Main Results:

• Ultrasound (US) assistance influenced cellular morphology based on foaming temperature.
• US led to a slight decrease in cell size and an increase in cell density.
• A significant decrease in thermal conductivity was observed with US assistance.
• Enhanced porosity was noted at higher foaming temperatures.
• Both laser and US methods yielded micro-porosity.

Conclusions:

• Ultrasound-assisted supercritical CO2 foaming is a viable out-of-autoclave technique for polymers.
• US significantly impacts cellular structure and reduces thermal conductivity.
• This study opens avenues for further research into US-assisted foaming processes.