Kevlar (Poly-paraphenylene terephthalamide) ((C₁₄H₁₀N₂O₂)n) — Properties, Uses & Safety

Overview

Kevlar is the trade name for poly-paraphenylene terephthalamide, a synthetic aramid fiber with the repeating unit formula (C14H10N2O2)n and a monomer molar mass of 238.25 g/mol. Developed by Stephanie Kwolek at DuPont in 1965, Kevlar appears as yellow fibers that are remarkably strong — approximately five times stronger than steel on an equal-weight basis — yet lightweight and flexible. The secret to Kevlar's extraordinary strength lies in its molecular structure: rigid para-oriented aromatic rings connected by amide bonds form long, straight polymer chains that align parallel to each other through extensive hydrogen bonding between the amide groups of adjacent chains. This creates a highly ordered, crystalline structure that resists stretching and cutting. Kevlar is best known for its use in bulletproof vests and body armor, where its ability to absorb and distribute the energy of a projectile can save lives. Beyond personal protection, Kevlar is used in aerospace composites, racing sails, bicycle tires, drumheads, fire-resistant clothing, and reinforcement of fiber-optic cables. The material does not melt but decomposes at around 500 °C, and it is resistant to most chemicals and solvents. Kevlar has no significant GHS hazard classifications in its fiber form. For chemistry students, Kevlar is a fascinating case study in polymer chemistry, illustrating condensation polymerization (the reaction between a diamine and a diacid chloride), the importance of hydrogen bonding in determining material properties, and how molecular-level design translates to macroscopic performance. It also highlights the contributions of women in chemistry — Stephanie Kwolek's accidental discovery during research on lightweight fibers for tires became one of the most important materials innovations of the twentieth century.

IUPAC Name

poly(imino-1,4-phenyleneimino terephthaloyl)

CAS Number

26125-61-1

PubChem CID

0

Molecular Formula

(C₁₄H₁₀N₂O₂)n

Molar Mass

238.245 g/mol

State at STP

solid

Appearance

Yellow fibers