Aramid Paper VS DuPont Paper

In high-temperature insulation, honeycomb structural materials, and electrical applications, aramid paper and DuPont paper are two commonly used high-performance materials. Many users feel confused during selection: Are they the same material, or completely different products?

This article provides a detailed comparison of aramid paper and DuPont paper—from definitions and performance to applications and cost—to help you make the right decision.

What Is Aramid Paper?

Aramid paper, also known as Nomex® paper, is a high-performance electrical insulating material made from meta-aramid fibers. It is widely used in transformers, motors, generators, and other electrical equipment that requires high thermal resistance and strong mechanical durability.

Key Features:

Thermal Class: Class H (180°C)

Mechanical Strength: Excellent tensile and tear resistance.

Electrical Insulation: High dielectric strength and low dielectric loss.

Chemical Stability: Resistant to most chemicals, oils, and contaminants.

Moisture Resistance: Low moisture absorption ensures long-term insulation performance.

Aramid paper is often combined with epoxy resins, polyimide films, or other insulation layers to create high-voltage, high-reliability composite insulation systems.

What Is DuPont Paper?

DuPont paper generally refers to kraft paper or aramid-based variants that have been specially treated using DuPont’s patented processes. It is widely used in high-voltage electrical insulation, including transformers, reactors, and high-voltage windings.

Key Features:

Thermal Class: Class H (180°C) or higher, depending on the specific product model.

Electrical Properties: Excellent insulation performance for both AC and DC.

Mechanical Durability: High tensile strength with good folding endurance.

Moisture Resistance: Reduced moisture absorption after special treatment.

Chemical Compatibility: Works well with various insulation resins.

Although DuPont paper and aramid paper share similar performance characteristics, DuPont’s patented processing techniques further enhance properties such as moisture resistance and resin adhesion.

Core Conclusion:

From a basic performance standpoint, all qualified aramid papers are inherently high-temperature resistant, possess strong electrical insulation, and are naturally flame-retardant.

However, DuPont Nomex® paper stands out as the industry benchmark due to its exceptional performance, long-term stability, and superior consistency.

Specific Applications of Aramid Paper and DuPont Paper

The application fields of both materials overlap significantly, and they are suitable for demanding industrial environments.

1. Motor Insulation

♦ Slot Insulation

Used as the liner on the inner wall of motor stator slots to isolate the windings from the iron core.

Aramid paper has excellent mechanical strength and toughness, ensuring it is not punctured or torn during winding insertion. Its high dielectric strength guarantees reliable insulation.

♦ Phase-to-Phase Insulation

Used to separate windings of different phases within the motor.

With strong thermal resistance, it allows motors to operate at higher temperatures. This supports increased power density or longer service life, making it a common choice for high-efficiency motors and new-energy vehicle drive motors.

♦ End Insulation Pads

Used to secure and insulate the winding end regions.

Aramid paper is flexible and easy to form, allowing it to wrap around winding ends and provide long-lasting protection.

2. Transformer Insulation

♦ Interlayer Insulation

In dry-type transformers, aramid paper and DuPont paper are wrapped between conductors.

They offer flame-retardant and self-extinguishing properties, significantly improving the fire safety of transformers.

This makes them ideal for indoor environments such as shopping malls, subway stations, and other locations with strict safety requirements.

♦ Insulation Sleeves and Structural Support

Used for conductor insulation and structural reinforcement inside transformers.

Aramid paper maintains dimensional stability and mechanical strength even at high temperatures, ensuring long-term transformer performance and structural integrity under short-circuit stress.

3. Generator Insulation

Large steam-turbine and hydroelectric generators require extremely high insulation performance for their winding bars.

Aramid paper can be used as the main insulation or reinforcement material to withstand electrical, thermal, and mechanical stresses and ensure long-term stable operation of the generator unit.

Cost and Supply Conditions

DuPont Paper (Nomex®):

Generally, its price is higher as a premium product in the market.

Pricing is influenced by brand value, R&D investment, and strict manufacturing control.

Supply is stable, but distribution channels are tightly regulated.

Other Brands of Aramid Paper:

More cost-effective, offering competitive pricing.

High-quality aramid paper produced by manufacturers in China and other countries provides the market with more affordable alternatives.

Aramid paper is a category of material, while DuPont paper (Nomex®) is the most well-known brand within this category.

In terms of performance and reliability, DuPont Nomex® paper remains an industry leader.

Other aramid paper brands continue to improve in technology and quality, offering significant advantages in price-performance ratio.

Your final selection should be based on a combination of factors, including:

Specific application scenarios

Required performance level

Budget considerations

Compliance and certification requirements

Regardless of which material you choose, it is strongly recommended to obtain samples from authorized and reputable suppliers for testing to ensure the product meets your application needs.