SynopsisA group of natural materials having anhydroglucose units linked by glycosidic bonds, as well as other related compounds, were irradiated with plasmas generated by a radio frequency field (13.56 MHz). Reactive sites created were characterized by electron spin resonance, chemiluminescence, infrared, and x-ray photoelectron spectroscopy. The free radicals are related to the number of glycosidic bonds, and their decays result in chemiluminescence. In the absence of moisture and oxygen, however, the radicals are stable. During plasma irradiation, carbonyl groups as well as free radicals are formed on surfaces, and the atom ratio of oxygen to carbon on surfaces increases. Within the reactor, thin films of polymers can be deposited on cotton fabrics by allowing the monomer to enter the reactor above the fabric that is in a horizontal position downstream from the external electrodes.

Cotton printcloth was treated with low-temperature, low-pressure argon plasma created by passing argon gas through a radiofrequency electric field of 13.56 MHz. Fabrics were exposed to plasma for 0–90 min. Pressure was maintained at 100 millitorrs and RF power at 40 watts. Plasma-treated cottons wetted readily and uniformly with water and aqueous dye solutions. Loss of weight on relatively long plasma treatment was greater than that due to usual removal of moisture under reduced pressure. Spectral changes observed by x-ray photoelectron-emission spectroscopy and infrared spectroscopy indicated surface oxidation of the cotton, and electron-spin-resonance spectra showed presence of free radicals. Although surface oxidation occurred, gross topographical changes of the cotton surface were not evident, even when viewed under the scanning electron microscope. The rate of wetting of argon-activated cotton was significantly greater than it was prior to plasma treatment. At comparable immersion times the amount of water wicked into an argon-activated cotton fabric was about twice that taken up by untreated material. The rate of drying was also faster after plasma treatment.

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SynopsisEffects of low temperatures upon fine structures of cotton pretreated with either liquid ammonia or caustic of mercerizing strength were investigated. Temperatures of cotton after impregnation with liquid ammonia were lowered by (1) liquid nitrogen, (2) acetone-Dry Ice, (3) acetone, or (4) simple evaporation. With alkali-impregnated fabrics, temperature was lowered by immersion in liquid nitrogen. Changes in fine structure of ammonia-and alkali-celluloses were evaluated by x-ray diffraction before and after removal of each swelling reagent. After treatment with either ammonia or caustic soda, extent of crystalline modification was increased as temperature was reduced. X-ray diffractograms taken while liquid ammonia was still present indicated that the cellulose I structure of cotton sheeting was converted to cellulose I11 a t liquid nitrogen temperatures; extent of conversion was approximately that obtained when a looser yarn structure was treated with liquid ammonia and the ammonia was removed by evaporation. When ammonia was removed with water, the cellulose I lattice was regenerated. In the presence of 23% NaOH, diffractograms indicated a significant decrease in order after a similar drop in temperature, but patterns were not of cellulose I1 until the NaOH was removed with water. Conversion to cellulose I11 or to cellulose I1 was achieved instantaneously when ammonia-and alkali-impregnated fabrics were immersed in liquid nitrogen.