Aramid is a generic term used to describe fibers from wholly aromatic polyamides. Since about 1965, several types of aramid fibers have been commercialized or are under development. Examples include 36fibers from poly(m-phenyleneisophthalamide) [MPD-I], poly(p-phenyleneterephthalamide) [PPD-T], and a copoly-terephthalamide from p-phenylene diamine and 3,4’-diaminodiphenyl ether [PPD/3,4’POP-T]. Figure 1 shows the chemical structures of these polymers.