The influence of the cyclic performance of paulownia wood semi-finished products on the strength indicators of corrugated paper

Abstract

Corrugated paper is a component of corrugated cardboard, which plays an important role in the formation of strength indicators, and its production in the last decade is one of the most developed sectors of the world pulp and paper industry. The article scientifically substantiates the differences between primary and reprocessed fibers and explains the essence of “irreversible keratinization” of the fiber. The paper examines the use of leafy semi-finished products obtained from paulownia wood by alkaline-sulfite and sodium methods for the production of corrugated paper with the study of the potential of its repeated processing. Patterns of decreasing paper strength indicators with increasing recycling cycles were obtained, which is explained by irreversible keratinization. It is shown that the use of semi-finished products obtained by the alkaline-sulfite method in the paper provides strength values for all indicators for the B-2 and B-3 grades after four times processing these fibers. It should be emphasized that in terms of absolute resistance to paper crushing, the obtained values meet the standards of the highest grade B-0 after a three-fold recycling cycle. The obtained data on the repeated processing of paper from natron SFP show that the greatest decrease in mechanical strength indicators is observed after the first cycle of processing, especially the absolute resistance to pressing. However, after the second cycle of processing, according to this indicator, a margin of strength is preserved, which is enough for the norms of the B-2 and B-3 grades. After five times of recycling such paper, the strength indicators remain at almost 50 % of the initial ones, in contrast to alkaline-sulfite paper – after four times of recycling, the potential is approximately one-third. Microphotographs of the paper surface and changes in fiber structure depending on the number of processing cycles confirmed the patterns obtained during the study.