Участие в 2 ND GREENERING INTERNATIONAL CONFERENCE Valladolid (Spain), 21st to 23rd March 2023
6. Applications in care and health products, food and agriculture technology Valladolid (Spain), 21 – 23th March 2023
THERMAL STABILITY OF CHITOSAN COATED PACKAGING PAPERS
Todorova D. , Yavorov N. , Lasheva V. , Vrabič Brodnjak U.
University of Chemical Technology and Metallurgy, Department of Pulp, Paper and Printing Art, St. Kliment Ohridski 8, 1756 Sofia, Bulgaria
University of Ljubljana, Faculty of Natural Sciences and engineering, Department of Textiles, Graphic Arts and Design, Snežniška 5, SI-1000 Ljubljana, Slovenia
Corresponding author email: todorova.dimitrina@uctm.edu
Abstract
Paper as a nonhomogeneous sheet material that is made essentially from fibers of plant origin is suitable for a weight variety of packaging applications. Based on the type of coating or finishing processes it could be a key material with an extremely wide range of properties, optimal for printing and wrapping; care and health products; food or agriculture and others. Paper aging depends not only on the depository conditions of the paper (temperature and relative humidity), the degree of light and temperature exposition, and some microbiological factors but also on the chemical composition of the fiber raw material and chemical additives used. Chitosan has been stated to be used as wet-end additive and as a coating in paper-manufacturing process, to improve barrier, mechanical and optical properties of variety of paper grades. On the other hand, it could be used as crosslinking agent. In this sense and in line with the increased chitosan treated or coated paper consumption as printing and wrapping papers, the aging stability of these papers is of a vast scientific and applied interest. In accordance with the above written, in developing this experiment, the aim was to prepare and study the thermal stability of chitosan-coated wood-free wrapping paper. Pulp sample and four paper samples (three of them coated with different chitosan quantity) have been examined for their structural-dimensional and strength properties together with the focus of the experiment – accelerated thermal aging at temperature of 105 °C and duration of 72 h and dynamic thermogravimetric analysis (TGA). The degree of color changes in the CIE Lab color space have been studied, bearing in mind that the changes in color characteristics define the stability over time and even more – the influence of chitosan coating. As a result, of the studies carried out it was found out that with increasing the chitosan coating, the ageing stability also increase, due to the improved crosslinking proses between chitosan and paper. During 72 h of accelerated thermal ageing, the color of the coated paper becomes yellowish corresponded to the amount of chitosan. The change of the weight of the paper samples as a function of temperature was monitored by TGA. When comparing the weight losses, it was found out that with increasing the chitosan coating the temperature of complete burning of the sample increased to 2.6 °C. In addition, the surface of the coated paper samples is more even and with increased barrier properties.
Keywords: Chitosan, Coating, Papermaking, Ageing, Thermal stability
Acknowledgements: Authors gratefully acknowledge the financial support of Scientific Research Fund, Bulgaria under project № 920 (КП-06-H49/1)
