PU Foam Core is a rigid polyurethane foam core material designed for composite sandwich panels. It offers excellent thermal insulation, high compressive strength, low water absorption, and strong bonding with various facings, making it ideal for construction, transportation, marine, and industrial applications.
PU Foam Core, also known as Polyurethane Foam Core, is a high-performance structural core material widely used in composite sandwich panels. It is engineered to deliver an optimal balance of mechanical strength, thermal insulation, dimensional stability, and processing versatility. Due to its closed-cell structure and customizable density range, PU Foam Core is extensively applied in construction, transportation, marine, cold-chain equipment, and industrial insulation systems.
Compared with traditional foam cores such as EPS or conventional rigid foams, PU Foam Core offers superior compressive strength, enhanced adhesion to skins, and excellent long-term thermal performance. These characteristics make it an ideal solution for both load-bearing and insulation-critical composite structures.
Material Composition and Structure
PU Foam Core is manufactured through a controlled chemical reaction between polyols and isocyanates, forming a rigid polyurethane foam with a predominantly closed-cell morphology. The closed-cell content typically exceeds 90%, which is critical for achieving low water absorption and stable thermal insulation.
Key structural characteristics include:
- Closed-cell microstructure for moisture resistance
- Uniform cell size distribution ensuring consistent mechanical properties
- High cross-link density for enhanced rigidity and dimensional stability
The formulation can be modified to meet specific requirements, such as flame retardancy, higher temperature resistance, or improved bonding compatibility with composite skins.
Manufacturing Process
The production of PU Foam Core involves advanced foaming and curing technologies to ensure uniform density and reliable performance. The general process includes:
- Raw material metering and mixing
Precisely controlled ratios of polyol, isocyanate, catalysts, blowing agents, and additives. - Foaming and expansion
The mixture reacts and expands within a mold or continuous production line, forming a rigid foam structure. - Curing and stabilization
The foam is cured under controlled temperature conditions to achieve full mechanical strength. - Cutting and surface finishing
Blocks or continuous panels are cut into required thicknesses and dimensions. Optional surface treatments or laminations can be applied.
This controlled process ensures consistent density, flatness, and surface quality suitable for downstream composite manufacturing.
Key Performance Characteristics
PU Foam Core is valued for its well-balanced physical, mechanical, and thermal properties.
Mechanical Properties
PU Foam Core exhibits excellent compressive and shear performance relative to its weight, making it suitable for structural sandwich panels.
| Property | Typical Value Range | Test Standard |
|---|---|---|
| Density | 30 – 300 kg/m³ | ISO 845 |
| Compressive Strength | 0.15 – 3.50 MPa | ISO 844 |
| Compressive Modulus | 5 – 150 MPa | ISO 844 |
| Shear Strength | 0.10 – 2.00 MPa | ISO 1922 |
| Tensile Strength | 0.20 – 2.50 MPa | ISO 527 |
Thermal and Insulation Performance
One of the primary advantages of PU Foam Core is its low thermal conductivity, which remains stable over long service periods.
| Thermal Property | Typical Value |
|---|---|
| Thermal Conductivity (λ) | 0.020 – 0.028 W/m·K |
| Operating Temperature Range | -50°C to +120°C |
| Dimensional Stability | ≤ 2% at elevated temperature |
These characteristics make PU Foam Core particularly suitable for cold storage panels, refrigerated transport, and energy-efficient building envelopes.
Moisture Resistance
Due to its high closed-cell content, PU Foam Core demonstrates excellent resistance to water absorption.
| Property | Typical Performance |
|---|---|
| Water Absorption (24h) | ≤ 2% by volume |
| Vapor Permeability | Very low |
| Resistance to Mold and Rot | Excellent |
This ensures long-term performance in humid or moisture-prone environments.
Fire Performance Options
PU Foam Core can be formulated with flame-retardant additives to meet international fire safety standards. Depending on the formulation, it can comply with:
- B1 fire rating (DIN 4102)
- EN 13501 fire classifications
- ASTM E84 (Class A with suitable facings)
While standard PU foam is combustible, fire-retardant grades significantly reduce flame spread and smoke development when used within composite systems.
Surface Compatibility and Lamination
PU Foam Core is highly compatible with a wide range of facing materials and adhesive systems. It bonds effectively with:
- FRP (Fiberglass Reinforced Plastic)
- Aluminum sheets
- Stainless steel
- Plywood and HPL
- Cementitious and mineral boards
The foam core can be supplied with plain surfaces or pre-laminated skins, improving production efficiency for sandwich panel manufacturers.
Typical Applications
Thanks to its versatility, PU Foam Core is used across multiple industries:
Construction and Building Systems
- Insulated sandwich wall and roof panels
- Cold room and cleanroom panels
- Prefabricated housing systems
Transportation
- Refrigerated truck bodies
- Caravan and RV panels
- Railway interior and insulation panels
Marine and Offshore
- Lightweight bulkheads
- Deck and superstructure panels
- Buoyancy and insulation components
Industrial and Energy
- HVAC insulation panels
- Equipment enclosures
- Pipeline insulation systems
Advantages of PU Foam Core
- High strength-to-weight ratio
- Excellent thermal insulation performance
- Low water absorption and dimensional stability
- Strong adhesion with composite skins
- Customizable density, thickness, and fire rating
- Long service life with minimal performance degradation
Available Specifications
PU Foam Core can be supplied in customized formats to meet project-specific requirements.
| Parameter | Available Range |
|---|---|
| Density | 30 – 300 kg/m³ |
| Thickness | 10 – 200 mm |
| Panel Size | Customized |
| Surface Finish | Plain, grooved, or laminated |
| Fire Rating | Standard / Flame-retardant |
Conclusion
PU Foam Core is a reliable and high-performance solution for composite sandwich structures requiring strength, insulation, and durability. Its combination of mechanical robustness, thermal efficiency, and processing flexibility makes it an essential core material across construction, transportation, marine, and industrial sectors.
For manufacturers seeking consistent quality, design flexibility, and long-term performance, PU Foam Core remains one of the most cost-effective and technically proven foam core solutions available on the market today.
FAQ
Q1: What is PU Foam Core?
A: PU Foam Core is a rigid polyurethane foam used as the core material in composite sandwich panels. It combines lightweight structure, mechanical strength, and superior thermal insulation, widely applied in building panels, refrigerated transport, and industrial insulation systems.
Q2: What density ranges are available for PU Foam Core?
A: PU Foam Core is typically available in densities from 30 kg/m³ to 300 kg/m³. Lower densities focus on insulation performance, while higher densities provide improved compressive and shear strength for load-bearing applications.
Q3: How does PU Foam Core compare with XPS or EPS foam cores?
A: Compared to XPS or EPS, PU Foam Core offers lower thermal conductivity, better adhesion to facings, and higher design flexibility. It is particularly suitable for applications where insulation efficiency and bonding strength are critical.
Q4: Is PU Foam Core waterproof?
A: PU Foam Core features a high closed-cell structure, resulting in very low water absorption. This makes it suitable for humid environments, cold storage panels, and applications exposed to moisture.
Q5: What fire performance options are available for PU Foam Core?
A: PU Foam Core can be supplied in flame-retardant grades, meeting standards such as DIN 4102 B1, EN 13501 classifications, or ASTM E84 when used in composite panel systems with appropriate facings.
Q6: What facings can be laminated with PU Foam Core?
A: PU Foam Core is compatible with FRP, aluminum, stainless steel, plywood, HPL, and cement boards. Its surface chemistry allows strong adhesion with most industrial adhesive and lamination systems.
Q7: What is the typical thermal conductivity of PU Foam Core?
A: The thermal conductivity of PU Foam Core generally ranges from 0.020 to 0.028 W/m·K, providing excellent long-term insulation performance for energy-efficient panels.
Q8: Can PU Foam Core be customized in size and thickness?
A: Yes. PU Foam Core can be produced in customized thicknesses, panel sizes, densities, and surface finishes to meet specific project or production requirements.
Q9: What are the common applications of PU Foam Core?
A: Common applications include insulated wall and roof panels, cold room panels, refrigerated truck bodies, RV panels, marine bulkheads, HVAC enclosures, and industrial insulation systems.
Q10: Is PU Foam Core suitable for structural sandwich panels?
A: Yes. High-density PU Foam Core provides excellent compressive and shear strength, making it suitable for structural sandwich panels where both mechanical performance and insulation are required.
