Evaluation of birch bark strength by quantitative study of hydrogen bonds by IR spectroscopy

The systems of hydrogen bonds (H-bonds) in natural natural birch bark and technical bleached eucalyptus cellulose have been compared by the methods of Fourier infrared spectroscopy. Study frequency intervals (wave numbers) of 3000–3700 cm–1 and 2700–3700 cm–1 contain the absorption region of hydroxyl groups of OH, whose frequencies in the order of 3400, 3300, 3200 cm–1 are most sensitive to the formation of H-bonds of cellulose. A distinctive feature of the study is that all measurements of IR-spectra of transmittance and mechanical influence were made on natural birch bark, elastic under longitudinal stretching. The decrease of transmittance far from absorption bands was due to scattering of radiation on natural heterogeneity of birch bark wood material, which due to high quality of cuttings turned out to be small enough to prevent detailed study of absorption spectra (absorptivity). To estimate parameters of H-bonds, we performed deconvolution of absorption bands of hydroxyl OH groups on 7 and 9 gauss contours in order to study the effect of methyl methylene on the regression coefficient R^ and study the nature of the interaction order in cellulosebearing raw material, the so-called characteristic «nose» for further research as it is not considered in this paper. In the following, only the parameters of the deconvolution contours related to hydroxyl groups were analyzed. It was assumed that each Gaussian deconvolution contour can be associated with a certain type of H-bond (hydrogen bond).The shift in the frequencies of the deconvolution components, i.e. the maxima of the Gaussian contours relative to the natural frequency of the hydroxyl group, not covered by the H-bond for this reason, was determined. Literature data on the correlation of H-bond energy with frequency shift were used to determine the H-bond energy. The relative density of H-bonds was estimated from the ratio of Gaussian deconvolution contour areas. The energies and densities were found to be different for all bond types. It was found that the densities of the strongest intermolecular hydrogen bonds, energies and bond lengths of the same order of magnitude of natural birch bark and technical bleached cellulose, when deconvolving the spectrum in the OH region without error are indicative and useful for comparative analysis with different species of hardwood and softwood cellulose, instead of the previously adopted high-tech bleached and unbleached condensed paper.

1. Fengel D. c haracterization of cellulose using deconvolution of the region of stretching vibrations of OH groups in Fourier transform IR spectra. Holzforschung, 1992, vol. 46, pp. 283–288.

2. Ivanova E.I., Gerasyuta S.M., Ivanov-Omsky V.I. Comparison of hydrogen bond systems in wood and paper. Forest Journal, 2016, iss. I, pp. 147–154. DOI: 10.17238/issn0536-1036.1.S.147-154. (In Russ.)

3. Ivanova E.I., Ivanov-Omsky V.I., Davydova I.A., Grinenko E.V., Leontyev L.L., Selikhovkin A.V. Change in the structure of hydrogen bonds in elm wood due to damage by the jetted scrubber Scolytusmultistriatus (MarshamColeoptera: Cureulionidae, Scolionidae, Scolytinae. Izvestia Sankt-Peterburgskoj Lesotehniceskoj Akademii, 2018, iss. 222, pp. 23–35. (In Russ)

4. Ivanova E.I., Smolin A.S., Zvonareva T.K., Ivanov-Omsky V.I. Research of the hydrogen bonds system in paper. Chemistry of Plant Raw Materials, 2015. DOI: 10.14258/jcprm/20151386. (In Russ.)

5. Ivanov-Omskiy V.I. IK-shektroskpiya vodorodnykh svyazey v D-glyukoze [IR Spectroscopy Bonds in D-Glucose]. Pis’ma v Zhurnal Tekhniiceskoy Fiziki [Technical Physics Letters], 2014, vol. 40(18), pp. 29–34. (In Russ.)

6. Lyang S.I. Marcheselt R.H. IR spectra of crystalline polysaccharides. 1. Hydrogen bonding in natural cellulose. J. Polim.Sci., 1959, vol. 37, pp. 385–395.

7. Shabiev R.O., Smolin A.S., Ivanov-Omsrii V.I., Zvonareva T.K., Trapeznikova I.N. Anewhands-on method to investigate the system of hydrogen bonds in paper. Izvestia Sankt-Peterburgskoj Lesotehniceskoj Akademii, 2020, iss. 230, pp. 100–113. DOI: 10.212 66/2079-4304.2020.230.100-113. (In Russ.)