What Are Aramid Fibers? Exploring Their Properties and ...

It might be challenging to visualize aramid fibers at first, but once you consider their applications in body armor, bullet-proof vests, and firefighter uniforms, it becomes clearer.

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Indeed, aramid fibers are a remarkable segment of the fiber family. They typically showcase a bright golden-yellow hue, although other colors are now available. The term ‘aramid’ derives from a blend of "aromatic" and "polyamide." Their exceptional strength-to-weight ratio and thermal resistance make aramid fibers integral to applications such as protective clothing.

However, the properties of aramid fibers extend beyond protective wear (which we will elaborate on shortly). These fibers are crucial in composite materials, various military uses, automotive applications, and similar industries.

1. History of Aramid Fibers

The utilization of aramid fibers was complex due to their resistance to dissolution in most solvents, presenting challenges in processing. The advancement of aromatic polyamides primarily arose from the discovery of lyotropic liquid crystalline aramids, particularly Kevlar®, a product of DuPont.

In the 1960s, Polish-American chemist Stephanie Kwolek, a researcher at DuPont, developed para-aramid, which is marketed as Kevlar®. Her team initially sought to create a lightweight, strong fiber for tires. The discovery of the lyotropic liquid crystalline aramid allowed them to devise a novel spinning technique using an anisotropic solution, paving the way for Kevlar's introduction.

Structure of Kevlar, a para-aramid

Kwolek’s innovation with Kevlar was revolutionary. In July 1999, she became the fourth woman inducted into the National Inventors Hall of Fame. DuPont recognized her remarkable contributions by awarding her the Lavoisier Medal for outstanding technical achievement, a distinction she uniquely holds among female employees.

A Firefighter in Toronto, Canada wears a Nomex hood

Conversely, aramid fibers became commercially available in the early 1960s prior to Kevlar's advent, with Nomex® being a meta-aramid fiber developed by DuPont. Dr. Wilfred Sweeny, a Scottish scientist in DuPont’s ranks, is credited with this invention.

Nomex® is characterized by excellent thermal stability, remaining intact without melting or catching fire in typical oxygen conditions. This unique quality quickly facilitated its use in protective apparel and air filtration systems, effectively replacing asbestos. Introduced to the market in 1967, Nomex® has significantly contributed to improving safety for countless professionals, including firefighters, pilots, and race car drivers.

Other countries also produce meta-aramid fibers, including Teijin in the Netherlands under the name Conex, Toray in Korea as Arawin, and various manufacturers in China and France under different trade names like New Star and Kermel.

A timeline detailing the evolution of aramid fibers provides insight into their development.

Development of Aramid Fibers

Year

Event

Producer

Base Polymer

Commercialization of Nylon

Introduction of Nomex fiber

DuPont Co., USA

MPD-1

Discovery of anisotropic polymer

Discovery of air-gap spinning

Introduction of fiber-B

DuPont Co., USA

(i)PBA
(ii)PPD-T

Introduction of Tejincorex
Commercialization of Kevlar

Introduction of Twaron
Introduction of Kermel
Introduction of Fenilon

Teijin Ltd, Japan & DuPont Co., USA
Akzo Chemicals BF, Netherlands
Rhone-Poulene, France
USSR

MPD-1
PPD-T
PPD-T
MPD-1
MPD-1