Trinidad Mares

Photochemical Initiation of Free Radicals in Cotton Cellulose

Cotton cellulose of the Deltapine variety, spun into 7s/3 yarns, was purified hy extraction with hot ethanol. followed 1Iy hoilÍ11,g in dilute sodium hydroxide solution. precautions being takcn to minimi7(’ oxidation hy air. The sodium, hydroxide sulution was remoBed hy washing thycc·llnlc~~e with distilled water; tills was followed 1~)~ souring with dilute acetic acid. neutralizing with dilute ammonium hydroxide, and again washing with di.,tjJ1cd, water ,’1151., ., After conditioning the cellulose ut 21 °C and fji~/ ’ kl 1, the resulting product had a moisture content of’ahout ~r/ and a viscosity-average molecu.lar. weight of about 700.000 ( 12 ~ : ’

Some Properties of Benzoylated Cotton

Protection of fibrous cotton cellulose from weathering degradation and from degrada tion on exposure to high energy radiation (as measured by breaking strength retention), by substitution of benzoyl groups on the cellulose molecule, was demonstrated. It can be concluded that the presence of the benzoyl groups affected the absorption of incident energy by the cellulose molecule and/or the localization of energy within the molecule.

Thermally Initiated Free-Radical Oxidation of Cellulose

Purified cotton cellulose was heated in the resonant cavity of the electron spin resonance spectrometer in static nitrogen, flowing nitrogen, and flowing air and in vacuum. The formation of free radicals in the samples of cotton was monitored at temperatures below 300°C. Cotton was treated with chemical additives and then heated in static nitrogen at atmos pheric pressure. At the same temperature of heating, a much greater concentration of free radicals was formed in purified cotton heated in static nitrogen than in cotton heated in flowing nitrogen or in vacuum. The rate of free-radical forma tion in cotton heated in flowing nitrogen was constant throughout the heating period. Cotton, heated at the same tem peratures and times in flowing air or in static nitrogen, showed a greater concentration of free radicals than cotton heated in flowing nitrogen. The effects of additives or the application of vacuum on the apparent energy of activation for the formation of free radicals in heated cotton were also investigated. The amount of char formed during pyrolysis, as indi cated by the intensity of the free-radical signal, was much greater for samples which contained additives or which were allowed to trap decomposition products than for untreated cotton purged free of volatile decomposition products, as they were formed.

The Effects of Gamma Radiation on the Chemical Properties of Methyl Cellulose

Methyl cellulose was irradiated in a solid state in air with gamma radiation from cobalt-60 to dosages of 1, 10. 15, 25, and 50 × 10 6 roentgens. Irradiation induced chain cleavage, demethylation, and carhonyl and acid group formation in the methyl cellulose. Peroxides and formaldehyde were detected in the irradiated materials. A marked postirradiation loss in acid groups was observed in the irradiated methyl cellulose. No changes in chain length or carhonyl content of the irradiated samples were observed during postirradiation storage. Radiochemical analyses of irradiated methyl-C 14 celluloses indicated that there were no postirradiation demethylations or loses of oxidized products originating in the methyl groups. Comparisons of radiochemical yields on irradiation of cellulose and methyl cellulose in air to a dosage of 50 × 10 6 roentgens indicated that methyl cellulose had higher yields of cham cleavage and acid groups and lower yields of carbonyl groups than cellulose. IBVl~,~’1’I(~.~’1’I( >:~~ of the ejects of h~h-energy radiation on cellttlose [2, 4, 14 indicated that irradiation induced an oxidative degradation. The molecules were altered by chain cleavage and the introduction of the carboxyl and carbonyl groups. On the basis of a detailed study 141 of the degradation products obtained on irradiation of purified cotton cellulose in an oxygen atmosphere with gamma rays to a dosage of 10~ roentgens. some suggestions have been made on the mechanisms by which these reactions were produced. It was suggeatecl that activation or ionization, either at or on the C, and C~ positions in the Vn11yc1rO~1tlC(>Se unit, resulted in cltain cleavage. When the C, position was affected, cltain cleavage occurred and ?-ketoglticonic acid was formed on the reducing end of the cellulose chain, utilizing one mole of oxygen and leaving an unaltered glucose unit on the nonreducing end of the other chain. Interaction of the radiation with the C, position resulted in chain cleavage. liberating the reducing end flf the chain as an unaltered glucose unit and producing a ketone group in the C, position on the nonreducing end of the other chain with utilization of ~ mole of oxygen. Phillips and Moody [25, 26 J proposed the occurrence of similar types of oxidative cleavage on irradiation of sucrose and dextran in aqueous solution. ()n the basis of this same study [4] of the degradation products of cotton cellulose irradiated in oxygen, it was suggested that radiation activation of the C~, C3, C,, and C6 positions of the anhydroglucose units resulted in the evolution of hydrogen and the introduction of reducing groups, either ketones or aldehydes, into the cellulose molecule. Much more definitive data will have to be obtained before a complete picture of the mechanism of interaction of high-energy radiation with cellulose can be estahlishecl. One way of learning more about this mechanism would be to compare the effects of radiation on cellulose with the effects on cellulose that has been altered by the introduction of simple substituents, such as a methyl group. A knowledge of the effects of high-energy radiation on’ cellulose and cellulose derivative’s and their postirradiation stability is necessary in any attempt to utilize this important new source of energy to produce improved cellulosic products. ’ Miller [23] found that irradiation of dry methyl cellulose produced a decrease in its specific viscosity. I Pr~!>ented in part at the Southwest and Southeast Regional Meeting of the American Chemical Society, New Orleans, Louisiana, December 7-9, 1961. = Present address: Alabama Point, Orange Beach, Alahama. 1 One of the laboratories of the Southern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture.

Rot Resistance of Some Aromatic Derivatives of Cotton Cellulose

We have previously reported the radiation resistance of fibrous cotton cellulose containing benzhydryl, trityl, benzoyl, naphthoyl, cinnamoyl, and carbamoyl groups [2-5, 12]. Based on excitation and fluorescence spectra of substituted. glycosides [2, 8-11, 13] and subsequent weather-resistance testing, we have shown that only the fibrous cellulose containing benzoyl groups had weather resistance [4]. Earlier, others had also shown that fibrous cellulose containing cinnamoyl groups were not weather resistant [7, 14]. \Ve have found that fibrous cotton cellulose containing cinnamoyl, naphthoyl, benzhydryl, and trityl groups, prepared as previously described [5], have rot resistance in soil burial tests [1(a)] (Table I). It would appear that the substitution of some aromatic groups on cellulose

Chromatographic Separation of the Cotton-Gin Trash, Bract, Sisal, and Jute Antigens into Two Fractions

The cotton-gin trash, bract, sisal, and jute antigens were separated into two fractions by Sephadex G-75 column chromatography. The first appeared in the chromatogram as a small, fast-moving fraction, and the second as a large, slow- moving one. Both fractions absorb uv light at 254 nm. Earlier work on the partially- purified antigens showed two bands by gel electrophoresis: a large, slow-moving band that stained heavily for carbohydrate but weakly or not at all for protein, and a small, fast-moving band that stained heavily for protein but less for carbohydrate, indicating the presence of a glycoprotein. The two fractions separated by column chromatogra phy were tested by immunodiffusion for antigenicity. The small, fast-moving fraction is immunologically active against cotton dust antibodies, but the large, slow-moving glycoprotein separated in this procedure is not.

Preparation of Methyl-C14-Cellulose from Cotton Cellulose

equation for this particular fiber is approxiniately R = 16 d + 460. Figure 2 sliow tlie yarn in diflerent stages of sivelling. Exactly why this is so is difficult to say without a iiiucli more careful analysis of tlie problem I t niay be clue to tlie fact that tlie swelling of viscose rayon is anisotropic in nature, that is, the traiisversal swelling is greater than the longitudiiial. Another suggestion, made by Baird [l], is that there is a differential longitudinal swl l ing between the inside and the outside of tlie curved fiber. There ought to be structural differences between these two layers, since an originally straight fiber is set in a curved form H e supposes that there is greater swelling of tlie inside layer, while in this case it must be of tlie outside layer. I t is, however, interesting to observe that the pheiioiiieiioti of reversible curvature changes with swelling, which was first observed with wool fibers, has a more general applicability. Fig. 2. Photograph of crimp changes.