Far-infrared spectrum of poly(p-phenylene terephthalamide)

Abstract
The polarized and unpolarized far-infrared (460-30 cm−1) spectra of poly(p-phenylene terephthalamide) (PPTA) fabric and fiber arrays are reported. These spectra are discussed and tentatively analyzed on the basis of the internal and external modes of the repeat unit of PPTA. To assist in band assignments, the spectra of potassium triiodide-treated PPTA fibers and of benzanilide and its benzene solution are also reported.