Kevlar

poly(p-phenyleneterephtalamide)



Kevlar is used to make bullet proof vests, trampolenes, and tennis rackets.

Microworlds (Lawrence Berkeley National Labs ) has a page about the strength of kevlar with several interesting graphic illustriations.
Synthesis of Kevlar


Ideas here are taken from the Encyclopedia of Polymer Science and Technology, Second Edition, from the article on Aromatic Polyamides (filed under Polyamides, Aromatic.)

Polyamides could be prepared by interfacial polymerization but this method yields a polymer with very high and very low molecular weight chains, which is not good for either film or fiber formation.

Aromatic polyamides can be synthesized by a low temperature polycondensation reaction of diacids and diamines, using amide solvents. 
     O        O
    ||        ||
HO - C - R1 - C - OH

       diacid


H - N - R2 - N - H
    |        |
    H        H
      diamine
The solvent must dissolve or at least swell the polymer. DMF and DMSO will react with an acid chloride, so they cannot be used. A tertiary amine may be added to facilitate the reaction as an acid acceptor.

A journal article about the synthesis has been summarized.








Last Update- October 15, 1995- wld