Nomex, developed in the 1960s by DuPont, is a flame-resistant meta-aramid material. It’s an aromatic polyamide with a unique molecular structure that contributes to its heat and flame resistance.
| Fiber Source | Synthetic, aromatic polyamide (aramid) |
| Weaving Patterns | Various, including plain and twill weaves |
| Dominant Colors | Limited range, primarily natural and dyeable to specific hues |
| Texture Spectrum | Smooth, lightweight, and resilient |
| Breathability Index | Moderate, with good moisture-wicking properties |
| Strength & Longevity | Extremely durable, resistant to heat, flames, chemicals, and radiation |
| Maintenance Needs | Special care required, often dry clean only, resistant to shrinking and stretching |
| Primary Applications | Firefighter gear, military uniforms, flight suits, electrical insulation |
| Ecological Impact | Moderate environmental impact, difficult to recycle |
| Major Exporters | Limited to countries with advanced chemical industries, such as the USA and European nations |
| Comparable Fabrics | Kevlar, other aramid fibers |
Its versatility extends beyond protective clothing, finding use in various industrial and household applications.
1. Composition and Properties
Research on thermal properties shows Nomex blended with Lenzing Viscose FR at an 80/20 ratio exhibits superior thermal behavior, offering an economical choice for flame-resistant fabrics due to the lower cost of Viscose FR.
Nomex is made from meta-aramid yarn, a type of synthetic fiber known for its high resistance to heat and flames. The key properties of Nomex fabric include:
- Very high temperature resistance.
- High durability and anti-static properties.
- Shrink resistance and ease of care.
- Comfortable to wear.
- Resistant to most industrial oils, solvents, and chemicals.
- Efficient dye absorption.
2. Applications
Studies on irradiated Nomex fabrics indicate a reduction in flame resistance with increased irradiation, though less significantly than tensile strength decrease, suggesting a potential decrease in protective efficiency over time. Incorporating particulate fillers in Nomex fabric composites like PTFE enhances wear resistance while maintaining friction properties, offering insights into environmentally friendly material enhancements.
Nomex is widely used in several industries for its protective qualities, especially in environments prone to high temperatures and flames. Common applications include:
- Protective clothing for firefighters, industrial workers, military personnel, and racing drivers.
- Fire-resistant applications in aerospace, like aircraft interiors and insulation for electrical components.
- Non-flammable protective layers in electrical equipment, such as transformers and motors.
3. Nomex in Clothing
Nomex fabrics in wet conditions reveal that moisture significantly impacts thermal resistance and water vapour permeability, essential factors in designing protective clothing for extreme conditions.
Nomex clothing refers to garments made from Nomex fabric, designed to offer flame resistance and heat protection. These garments do not burn, melt, or drip, and their protective properties are permanent. They are used in various industries like oil and gas, petrochemical, chemical, pharmaceuticals, and electric utilities.
Variations in Nomex Clothing
- Nomex IIIA: Commonly used in the oil and gas industries for flash fire protection. It’s composed of 93% Nomex fiber, 5% Kevlar®, and 2% antistatic fiber.
- Nomex MHP: A blend used for arc flash and multi-hazard applications, combining aramid, lyocell, modacrylic, and anti-static materials.
- Westex® CXP: Known for its softness, made with 100% Nomex III A, suitable for various protective applications.
4. Comparison with Other Fabrics
Research on Nomex fabric composites demonstrates that surface modifications, like bromine-etching and bromoacetic acid-grafting, can significantly improve wear resistance, suggesting enhanced durability for protective gear.
Here’s a comparison table that captures the differences and characteristics of Nomex, other Flame Resistant (FR) fabrics, and their combinations with materials like Kevlar and cotton.
| Comparison | Nomex | Other FR Fabrics | Kevlar Nomex Fabric | Nomex and Cotton |
|---|---|---|---|---|
| Material Type | Synthetic aramid fiber | Varies (can be different compositions) | Blend of Kevlar and Nomex aramid fibers | Blend of synthetic Nomex and natural cotton |
| Flame Resistance | Inherent flame resistance | Flame resistance varies; may be treated | Enhanced flame resistance | Superior flame resistance compared to cotton |
| Durability | Highly durable | Varies depending on composition | Further increased strength and durability | Varies, but Nomex enhances durability |
| Strength | Strong | Varies | Significantly stronger due to Kevlar addition | Stronger than cotton alone |
| Heat Resistance | Excellent heat resistance | Varies; generally good but depends on treatment | Enhanced heat resistance | Higher heat resistance than cotton |
| Applications | Wide range of protective clothing | Specific to the type of FR fabric used | Demanding applications requiring extra strength | Applications requiring a balance of comfort and protection |
This table provides a comparative overview of Nomex and other FR fabrics in various combinations, highlighting their material properties, resistance qualities, and typical applications.
5. Key Specifications and Cost
A study on Nomex with different salt concentrations shows that even minimal sodium chloride content affects thermal comfort properties of wet fabrics, highlighting considerations for marine applications.
Nomex fabric’s specifications are centered around its heat and flame resistance, durability, and protective qualities in extreme conditions.
The cost of Nomex fabric can be higher than standard fabrics due to its specialized properties and the complex manufacturing process involved.
6. Certification and Standards
Nomex fabrics are tested rigorously to meet international safety standards, ensuring they provide reliable protection in hazardous conditions. This involves burn tests and evaluations under extreme conditions to ascertain their protective efficiency.
Developments in PTFE/Nomex hybrid composites show potential for reduced wear in dry sliding conditions, with graphite fillers improving wear resistance, key for high-performance applications.
7. Conclusion
Research into electrically conductive Nomex composites looks into the potential for high-temperature stable conductive fabrics, opening new avenues for smart textiles in protective clothing.
Nomex fabric’s unique properties make it an invaluable material in industries requiring protection from high temperatures and flames. Its versatility extends from protective clothing to various industrial applications, offering safety and reliability where it matters most.