Thermal Insulation Foam of Polystyrene/Expanded Graphite Composite with Reduced Radiation and Conduction.

Area of Science:

• Materials Science
• Thermal Engineering
• Nanotechnology

Background:

• Radiative and solid thermal conductivity significantly contribute to heat transfer in polymer foams.
• Existing thermal insulation materials often face limitations in reducing these specific heat transfer components.

Purpose of the Study:

• To investigate the thermal insulation behavior of polystyrene (PS) foams incorporating expanded graphite (EG).
• To develop a superthermal insulating composite foam by optimizing material composition and foaming processes.

Main Methods:

• Incorporation of low concentrations (≤2 wt%) of expanded graphite (EG) into polystyrene (PS) foams.
• Systematic and quantitative investigation of thermal insulation properties.
• Optimization of the supercritical CO2 foaming process using a co-blowing agent.

Main Results:

• 1 wt% EG addition to PS foam blocks suppressed over 90% of radiative thermal conductivity.
• Total thermal conductivity was reduced from 36.5 to 30.2 mW·m⁻¹·K⁻¹ with 1 wt% EG.
• Superthermal insulating PS/EG foam with a record low thermal conductivity of 19.6 mW·m⁻¹·K⁻¹ was achieved.

Conclusions:

• Composite material and foaming process design are crucial for achieving superthermal insulation.
• High infrared absorption additives, large expansion ratio foams, and low gas conductivity co-blowing agents are key strategies.
• This approach enables the development of advanced insulating materials for various applications.