Phase-Change Materials as Cryo-Shock Absorbers in Rigid Polyurethane Cryogenic Insulation Foams.

Area of Science:

• Materials Science
• Polymer Chemistry
• Thermal Engineering

Background:

• Rigid polyurethane (PU) foams are widely used in insulation and construction.
• Phase-change materials (PCMs) offer potential for enhanced thermal energy storage in materials.
• Integrating PCMs into PU foams presents challenges due to viscosity changes during processing.

Purpose of the Study:

• To investigate the impact of microencapsulated PCMs on the properties of rigid PU foams.
• To evaluate changes in density, thermal conductivity, mechanical strength, and adhesive properties.
• To understand the influence of PCM concentration on foam structure and performance.

Main Methods:

• Preparation of rigid PU foams with varying concentrations of microencapsulated PCMs (5% and 10%).
• Measurement of foam density, thermal conductivity, compressive strength, tensile strength, and adhesive strength.
• Analysis of cellular structure and thermal properties using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA).

Main Results:

• Increased viscosity during processing led to a slight rise in foam density (up to 9%) with higher PCM content.
• Thermal conductivity remained stable, preserving the closed-cell structure of the PU foam.
• Compressive and tensile strengths decreased with increased PCM loading due to cellular defects, but adhesive strength to aluminum improved at 5% PCM.
• PCM incorporation increased the glass transition temperature and influenced the overall mechanical behavior.

Conclusions:

• Microencapsulated PCMs can be incorporated into rigid PU foams, offering potential for improved thermal energy storage.
• Careful control of PCM concentration is crucial to balance enhanced functionality with potential compromises in mechanical integrity.
• The study highlights the trade-offs between density, mechanical properties, and thermal performance when using PCMs in PU foams.