Summary:
- PE foam is a thermoplastic with sealed, water-resistant cells, ideal for robust, moisture-proof cushioning. PU foam is a thermoset, available as soft open-cell or rigid closed-cell, offering tuneable comfort and insulation
- PE’s inert, cross-linkable structure delivers consistent resilience; PU’s reactive system allows custom density and feel
- Compared density, cushioning, thermal insulation, temperature range, and fire safety for each foam
- PE excels in packaging, sports, and HVAC; PU leads in furniture, acoustics, and automotive interiors
- Hybrid PE-PU laminates combine structural strength with plush comfort
- Checklist covers ILD, thermal conductivity, fire rating, fabrication, chemical resistance, and lead times.
Polymer foams are essential for cushioning, insulation, and sound dampening — delivering high performance at a fraction of the weight of solid plastics. The 2 main types, polyurethane (PU) and polyethylene (PE) foam, offer distinct advantages. Selecting the wrong type can increase costs, risk compliance failures, or complicate manufacturing.
This guide breaks down the chemistry, benchmarks key properties, and matches each foam to its ideal industry use.
Understanding Foam Types and Chemistry
PE foam is a thermoplastic, expanded with a blowing agent to form sealed, water-tight cells. PU foam is a thermoset, foaming during cure and available in both soft open-cell and rigid closed-cell forms.
What Is PE Foam? Structure and Composition
PE foam is created by polymerising ethylene and expanding it with a blowing agent.
- Closed-Cell Structure: Sealed gas pockets block water, boost buoyancy, and provide firm, resilient support.
- Performance: Stiff cell walls resist compression set, ensuring reliable cushioning over repeated use.
- Density: Engineering grades start at around 25 kg/m³, increasing with strength requirements.
What Is PU Foam? Reaction Process and Variants
PU foam forms when isocyanate and polyol react, creating a foam that can be tailored for softness or rigidity.
- Open-Cell or Closed-Cell: Open-cell PU absorbs sound and offers plush comfort; rigid closed-cell PU delivers high insulation.
- Customisable: Formulation can be adjusted for density, resilience, and fire performance.
- Density Range: PU foams are available in a wide range of densities to suit different applications.
Key Property Comparison for Material Selection
Select foam by matching its impact absorption, thermal insulation, and fire safety to your project’s requirements.
Density, Cushioning, and Impact Resistance
Foam density (kg/m³) and cell morphology govern how well a material absorbs shocks and springs back.
- PE Foam: Closed-cell, firm rebound, high resistance to compression set. Ideal for protecting heavy or valuable items from repeated impacts.
- PU Foam: Open-cell, soft, progressive compression. Excellent for vibration damping and comfort, but less durable under heavy loads.
Thermal Insulation and Operating Temperatures
Thermal conductivity (λ) gauges how much heat flows through a material, the lower the figure, the better the insulation.
- Rigid PU Foam: Thermal conductivity (λ) 0.02 – 0.03 W/m·K. Top choice for HVAC panels and cold-chain transport.
- PE Foam: λ 0.033–0.040 W/m·K. Chosen for moisture resistance and reliable insulation in damp environments.
- Temperature Range: Standard PE works from –60 °C to 80 °C (up to 110 °C if cross-linked). PU spans –50 °C to 120 °C, depending on formulation.
Flammability Ratings and Fire-Retardant Properties
Both PE and PU foams require modification for fire safety.
- PU Foam: Can achieve UL 94 V-0 or FMVSS 302 compliance.
- PE Foam: Typically reaches V-2 unless heavily filled.
- Smoke and Toxicity: For enclosed spaces, specify low-smoke, halogen-free grades to minimise toxic emissions.
Application Suitability by Industry
Match foam type to the dominant stresses and compliance needs of your sector.
PE Foam in Packaging, Sports, and HVAC
The attributes of water resistance, strength, and closed-cell integrity make PE foam suitable for demanding environments.
- Packaging: Protective inserts, flotation blocks, and returnable case liners. Closed cells resist water, oils and chemicals.
- Sports & Leisure: Martial arts mats, life vests, helmet, and boot spacers. Durable, buoyant, and impact-absorbing.
- HVAC: Pipe and duct insulation. Closed-cell structure prevents condensation and thermal bridging.
PU Foam in Furniture, Acoustics, and Automotive
Open-cell PU foam cushions and absorbs sound, making it essential for comfort and noise control.
- Furniture & Bedding: Progressive compliance for seat cushions, mattresses, and armrests.
- Acoustics: Open-cell panels absorb airborne noise and reduce reverberation in machinery enclosures.
- Automotive: Low-VOC grades for seats, headliners, and trim, combining comfort with noise and vibration control.
When Hybrid Laminates Offer a Better Fit
Hybrid laminates combine the strengths of both foams.
- Concept: Bonding PE and PU, or adding foil/fabric facings, merges structural strength with comfort.
- Benefit: A rigid PE or EPS core provides support, while a soft PU surface delivers cushioning — ideal for multi-functional components.
Curious where else PE and PU foams excel?
See the industries that rely on these foams for packaging, seating, insulation, and more.
Checklist: Matching Foam to Your Application
Before specifying, confirm the right material before issuing a purchase order.
Performance Priorities: Cushioning, Insulation, Durability
Check every foam against these three benchmarks before approval:
- Cushioning: Match ILD and density to expected loads and cycles. Use open-cell PU for comfort, cross-linked PE for energy return.
- Thermal Insulation: For cold-chain, select closed-cell PU with thermal conductivity near 0.023 W/m·K and add vapour barriers as needed.
- Durability: Specify compression set ≤5 %. Use abrasion-resistant skins for high-wear surfaces.
Fabrication Needs: Die-Cutting, Thermoforming, CNC Profiling
Both PE and PU foams are highly adaptable to modern fabrication methods, supporting efficient, precise production for a wide range of applications.
- Thermoforming (PE Only): As a thermoplastic, PE foam can be heated and deep-drawn into complex shapes, making it ideal for high-volume production of trays, medical packs, and custom inserts with tight tolerances.
- Die-Cutting (Both): Both foams can be cleanly punched into pads, gaskets, or sheet stock, enabling rapid, repeatable mass production for packaging, automotive, and appliance components.
- CNC Profiling (Both): Computer-controlled cutting allows for intricate, low-volume parts — perfect for prototypes, custom inserts, and detailed assemblies in electronics or furniture.
Selecting the right fabrication route ensures cost-effective, high-quality results tailored to your sector’s needs.
Compliance Factors: Safety, Chemical Tolerance, Lead Times
Before finalising your foam specification, confirm these critical compliance and supply factors:
- Regulatory Compliance: Ensure all required standards are met — UL 94 for fire safety, FDA for food contact, REACH for chemical safety, and any sector-specific certifications. Fire-retardant or low-extractable grades may increase cost but are essential for compliance.
- Chemical Tolerance: For exposure to oils, fuels, or solvents, opt for chemically inert PE foam. PU foam may soften or degrade more quickly in harsh environments.
- Supply Reliability: Verify that your chosen density and additive mix are available at the required volume and within your project’s lead time. Delays in supply can disrupt production schedules and increase costs.
A thorough compliance check minimises risk and ensures your finished product meets all operational and regulatory demands.
Choosing the Right Foam for Your Application
Selecting the right foam ensures optimal performance and compliance for your sector.
We offer expert advice, rapid prototyping, and in-house production — delivering finished foam parts to your exact requirements.
Contact us for tailored foam recommendations, samples, and a competitive quotation today.
