| The physical and chemical structure of dyed and undyed historic cotton samples recovered from the site of a deep ocean shipwreck, a modern reference cotton, and a sample of the reference cotton immersed at the ocean site for three months were studied with five analytical methods: optical microscopy, scanning electron microscopy, FT-IR microspectroscopy, x-ray diffractometry, and energy dispersive spectroscopy.;The results indicate that the physical macro and micro structure of the two historic cotton fibers have been altered during their long-term exposure to the deep ocean environment, but their cellulosic composition has been retained. X-ray diffraction crystallinity ratios and the infrared crystallinity indices indicate that the undyed historic marine cotton displays increased crystallinity because of the biodegradation it sustained. Crystallite size in the dimension ;Particulate deposits and deposit layers encrusting entire fiber surfaces were observed. The observed black deposits contain iron and sulfur, and are likely to have formed as a result of microbial sulfate reduction. Two types of cellulolytic microorganisms were found, and they attack the undyed cotton fiber in two distinct manners: layer to layer attack by rod-shaped microorganisms, and wall penetration by oval-shaped ones. It was found that dyed historic cotton was mordanted with tin, which also functioned as a biocide and protected the fiber from biodegradation.;The results obtained from the five analytical methods also indicate that the methods are applicable methods for the study of small samples, achieving relatively high precision and accuracy. Second derivative infrared spectra provided reliable peak identification. The peak fitting method applied to the x-ray spectra resolved more diffraction lines than those by the methods reported in the literature. In addition, more crystalline structure information is revealed by fitting the x-ray spectra through a Gaussian function without phase separation than by polynomial fitting methods of phase separation reported in the literature. |
