Polyethylene foam is a closed-cell, semi-rigid foam made from polyethylene polymer, known for its shock absorption, chemical resistance, and lightweight characteristics. In aviation, it is widely used for cushioning, packaging, gap-filling, and vibration damping in non-critical interior and cargo applications—particularly where impact protection is prioritized over flame resistance.

Background and Evolution

Polyethylene foam (PE foam) has been commercially available since the mid-20th century and is commonly made via chemical or physical foaming processes. Its wide use in aerospace logistics, protective packaging, and cabin components grew alongside the aviation industry's need for lightweight, damage-resistant materials for both manufacturing and in-flight service.

However, due to its poor inherent fire resistance, its use in commercial aircraft interiors is limited to non-cabin applications unless it has been treated or laminated with fire-retardant layers. More advanced cross-linked PE foams and fire-retardant variants have allowed for broader application, particularly in cargo hold liners, padding, and protective housing for equipment.

How Polyethylene Foam Is Used

• Protective Packaging: Custom-cut foam inserts for avionics, cabin parts, and delicate equipment during shipment and storage.
• Gap Fillers & Gaskets: Used between panel joints or insulation layers to reduce rattle and seal gaps.
• Flooring & Seat Cushion Layers: Occasionally used under carpets or as a low-density core layer in seating systems (with fire-retardant covering).
• Cargo Hold Padding: Provides lightweight, damage-tolerant lining for sensitive cargo.
• Vibration Isolation: Used beneath avionics racks or lightweight equipment to absorb mechanical vibrations.

Why Polyethylene Foam Is Used

• Lightweight: Extremely low density (as low as 24–40 kg/m³), contributing to overall weight reduction.
• Shock Absorption: Excellent energy absorption properties for packaging and vibration damping.
• Water and Chemical Resistance: Naturally hydrophobic and resists oils, solvents, and other fluids.
• Flexible & Formable: Easily cut, die-cut, or molded into custom shapes.
• Cost-Effective: Relatively inexpensive to produce and process.

Technical Specifications

• Base Material: Low- or high-density polyethylene (LDPE/HDPE), cross-linked or non-cross-linked.
• Density Range: 24–120 kg/m³ (1.5–7.5 lb/ft³), depending on application.
• Thermal Conductivity: ~0.033–0.040 W/m·K (varies by type).
• Operating Temperature Range: −60°C to +90°C (−76°F to +194°F); higher with cross-linked versions.
• Flammability: Poor in untreated forms (highly flammable); fire-retardant versions available.
• Compression Set: Low, meaning good rebound after compression.

Comparison to Alternative Materials