Lightweight, high strength and low cost, polyurethane composites are quietly changing the material landscape in multiple industries.

In the current era of pursuing energy conservation, environmental protection, low carbon and high efficiency, the pace of innovation in the field of materials is accelerating. Polyurethane resin and its composite materials, as a new generation of high-performance engineering materials, are challenging traditional metal materials (such as aluminum alloys) and traditional unsaturated materials (such as unsaturated polyester resins) in multiple application fields.

This material, with its unique comprehensive performance, offers a brand-new solution for engineering design.

01 The Rise of Polyurethane Composites

With the advancement of material research and development technology and equipment, as well as the mastery and improvement of the forming technology and process of polyurethane and fiber composites, polyurethane, as a brand-new material, has entered the field of composite materials that has long been dominated by unsaturated resins, epoxy resins, phenolic resins, etc.

Polyurethane composite materials are new types of polymer materials formed by compounding polyurethane resin as the matrix and glass fiber and other materials as reinforcements through specific molding processes. This combination achieves complementary performance advantages, overcoming the problems of pure polyurethane such as easy deformation and insufficient strength, while also making up for the shortcomings of glass fiber such as high brittleness and difficulty in molding.

At the 2025 China International Aluminium Industry Exhibition, the solution of polyurethane resin replacing aluminium materials has become the focus of attention for many domestic and foreign manufacturers, indicating that polyurethane resin may become one of the key materials in the future manufacturing industry.

02 A comparison of performance and economy with aluminum alloys

1. Lightweighting advantage

The density of polyurethane composite materials is very low, only about 2.0-2.1g /cm³, which is equivalent to 70-75% of the density of aluminum alloy (about 2.7g /cm³), and it has obvious advantages in lightweighting.

Components made of polyurethane composite materials are 15% to 30% lighter than those made of traditional aluminum alloy materials. This is of great significance for application fields that require weight reduction, such as new energy vehicles and aerospace.

2. Strength performance comparison

Polyurethane glass fiber composite materials possess outstanding physical properties, with their longitudinal tensile strength and flexural strength reaching over 1000MPa, while the tensile strength of 6063-T5 aluminum alloy is only around 160MPa. This means that the strength of polyurethane composites is 6 to 7 times higher than that of aluminum alloys.

The flexural modulus of polyurethane composites is close to that of aluminum alloys, but their specific strength (the ratio of strength to density) far exceeds that of aluminum alloys, making them an ideal choice for weight-sensitive applications.

3. Corrosion resistance and durability

The corrosion resistance of polyurethane composite materials is extremely outstanding, and common acids, alkalis, salts and other substances will not have an impact on them. Glass fiber composite materials do not undergo hydrolysis reactions in moist air and possess excellent water resistance and resistance to damp heat aging.

After two years of outdoor exposure, the glass fiber reinforced polyurethane composite material that has undergone anti-aging treatment shows no obvious discoloration or cracking in appearance, and the decline in mechanical properties is less than 15%, which is far superior to the unreinforced polyurethane material and some traditional plastic materials.

4. Insulation performance and safety

Polyurethane composite materials are poor conductors of heat and electricity, with a thermal conductivity of only about 0.3W/MK, approximately 0.4% (4‰) of that of aluminum alloy, making them excellent insulating materials.

In terms of electrical properties, the volume resistivity of polyurethane composite materials can reach over 1×10¹⁴Ω·cm, demonstrating excellent insulation performance. For photovoltaic modules, the use of non-metallic frame encapsulation can significantly reduce the possibility of forming leakage circuits, which helps to minimize the occurrence of PID (Potential Induced Decay) phenomena and enhance the power generation efficiency of the solar panels.

5. Cost advantage

In terms of raw material costs, polyurethane resin has a distinct advantage, with its cost being only one third of that of aluminum materials. Take photovoltaic frames as an example. The quoted price for 182 composite material frames is approximately 55 yuan per set, while that for aluminum frames is about 70 yuan per set, which is 15 yuan cheaper per set. For the 550W component, it is equivalent to a cost reduction of 2.7 cents per W.

Polyurethane composite materials can achieve integrated molding of complex structures through injection molding, compression molding and other processes, reducing welding and machining steps, further improving production efficiency and lowering processing costs.

03 Compared with the performance of unsaturated materials

1. Mechanical property advantages

Compared with unsaturated polyester resin, the strength and stiffness of polyurethane resin are 2 to 5 times higher. Polyurethane composite materials have better toughness and impact resistance. After processing and punching, the edges of their products have very few or even no microcracks.

Polyurethane pultruded products have higher strength performance and can be used in application fields where polyester resins cannot meet the requirements. They can replace steel and aluminum in the construction, infrastructure and transportation markets.

2. Improvement of process performance

The polyurethane pultrusion process can be processed at a higher production speed and causes less waste compared with unsaturated polyester resin. When using polyurethane pultrusion, glass fiber roving without twisting can usually be used instead of glass fiber mat, which simplifies the production process and reduces costs.

Polyurethane resin has a two-component system and exhibits excellent wettability and high adhesion to glass fiber reinforced materials, as well as low void ratio and low shrinkage rate. Compared with traditional pultrusion resins, its performance is significantly improved.

3. Environmental friendliness

Polyurethane resin does not contain volatile substances such as styrene, and the production site has no pungent smell, minimizing the impact on the environment and workers' health to the greatest extent. This is in sharp contrast to unsaturated polyester resins, which usually contain styrene monomers and release harmful fumes during processing.

04 应用领域案例

1. 光伏行业

Polyurethane composite material frames have become a good alternative to aluminum alloy frames in the photovoltaic field, especially suitable for harsh environments such as offshore photovoltaic and high salt and high humidity. Its insulating properties help reduce PID phenomena, improve power generation efficiency, and at the same time, it is light in weight and low in cost, providing a more economical solution for photovoltaic power stations.

2. Energy-saving doors and Windows and buildings

Polyurethane pultruded window frames have excellent thermal insulation performance, with a thermal conductivity of only 0.22 W/m·K, approximately 1/700 of that of aluminum alloy, making them an excellent insulating material.

The linear thermal expansion coefficient of the window frame is approximately 7×10⁻⁶/K, which is much lower than that of aluminum alloy and similar to that of the wall, ensuring the sealing performance of the door and window when the temperature changes. The heat transfer coefficient of the entire window using polyurethane composite materials can be as low as 1.5-1.8 W/(m²·K), meeting the high-standard energy-saving requirements.

3. Transportation

In the field of new energy vehicles, polyurethane composite materials are used in components such as battery pack casings and motor brackets, achieving energy efficiency improvements through weight reduction. Polyurethane composite materials are also used for container floors, which can reduce weight by 22% compared with traditional wooden floors, and extend the service life from 5 to 10 years to over 20 years.

4. Electricity and infrastructure

Polyurethane composite materials are used in power facilities such as cable troughs and cable trays, featuring excellent insulation and corrosion resistance. In the railway field, polyurethane sleepers have a longer service life (more than three times longer) than traditional wooden or concrete sleepers, and are resistant to hydrolysis, grease, seawater, frost and deicing salt.