When you are searching for a fiber or yarn for specific application requirements, there are many options to choose from. Meta-aramid and para-aramid yarns and threads are two popular choices for heat resistance and superior tensile strength.
Between Nomex™ and Kevlar™, you may find that one meets your specific needs however, you can also find comparable alternatives with similar properties and sizes from other aramid fiber producers.
Its important to understand the properties of meta-aramid and para-aramid to be able determine which is the best choice for your application.
The Key Differences Between Meta-aramid and Para-aramid Yarn
There are a few key differences between the two, specifically in the make-up of the fibers. Meta-aramids—commonly known as Nomex™—are temperature, chemical degradation and abrasion resistant. Meta-aramid is manufactured by wet spinning, the result is a semi-crystalline fiber with the molecular chain oriented along the fiber axis. They have a tenacity of about 5.6g/den and can withstand stress during fire exposure and high temperatures.
In contrast, para-aramids—commonly known as Kevlar™—are incredibly strong. Para-aramids are created using a dry-jet wet spinning method, resulting in a fully extended liquid crystal chain along the fiber axis. Para-aramids display a higher degree of crystallinity which increases the fiber’s strength. In fact, they are manufactured with a much higher tenacity of 23g/den.
The meta-aramid’s high resistance to heat makes it the perfect material for electrical insulation, protective gear and heat shields in vehicles. The para-aramid’s high strength and modulus is commonly used as strength members in cables, hose reinforcement and ballistics protection.
Multi-Filament Para Aramid vs. Meta Aramid - Physical Property Comparison
|Fiber Type||Meta-Aramid||Standard Tenacity Para-Aramid||High Modulus Para-Aramid|
|Typical filament size (dpf)||2||1.5||1.5|
|Specific Gravity (g/cm3)||1.38||1.44||1.44|
|Tenacity (gpd)||4 - 5||20-25||22-26|
|Initial Modulus (g/dn)||80-140||500-750||800-1000|
|Elongation @ Break (%)||15-30||3-5||2-4|
|Continuous Operating Temperature (F)||400||375||375|
|Decomposition Temperature (F)||750||800-900||800-900|
|Limiting Oxygen Index (LOI)||28-30||25-28||25-28|
Various Types and Sizes
Meta-aramids come in two different types: spun, often used in sewing applications for clothing, and continuous filament which boasts a higher strength and is perfect for reinforcement and strength member type applications. Para-aramids also come in spun and continuous filament types.
Meta-aramids have a filament size of 2 dpf and para-aramids typically a filament size of 1.5 dpf. Between the two, the available denier sizes are not always equivalent however, many different sizes can be constructed using the common multi-filament base denier sizes that are available from the major aramid fiber producers.
Common Multi-filament Para and Meta Aramid Types and Denier Sizes
|Meta-Aramid||Standard Tenacity Para-Aramid||High Modulus Para-Aramid|
|Common Denier Sizes||1200||400||1420|
|Common Brand Names||Nomex™||Kevlar™, Twaron™, Alkex™, Heracron™|
Service Thread manufactures a wide variety of aramid products for many different industrial applications. Let our experts at Service Thread know if you need help determining the right aramid type and construction for your application!