What are the differences in thermal insulation properties between plastic types?

Thermal insulation properties vary significantly across different plastic types due to their distinct chemical structures and physical compositions. Expanded polystyrene (EPS) and extruded polystyrene (XPS) foam plastics demonstrate excellent insulation capabilities with R-values typically ranging from 3.6 to 5.0 per inch, making them popular choices for construction insulation. Polyurethane foam offers even higher performance, achieving R-values between 5.6 and 8.0 per inch due to its closed-cell structure containing insulating gas.

Polyethylene and polypropylene, while useful for various applications, provide relatively poor thermal insulation compared to specialized foam plastics. Their solid molecular structure allows greater heat transfer, resulting in lower R-values. The insulation effectiveness of plastics primarily depends on their ability to trap air or other gases within their cellular structure. Closed-cell foams generally outperform open-cell structures because they minimize convective heat transfer.

Additional factors influencing thermal performance include material density, thickness, and the presence of reflective surfaces. Some plastics can be enhanced with additives like infrared attenuators to reduce radiant heat transfer. Understanding these differences helps engineers and designers select appropriate materials for specific thermal management requirements in construction, packaging, and industrial applications.