Influence of corrugate production processes on strength of cardboard and morphologigal characteristics of fibers under cyclic use

Abstract

In the production of corrugated cardboard, corrugated paper and flat layer board are exposed to high temperatures. In this work, the influence of high temperature on the strength properties of cardboard and the morphological characteristics of fibers in cardboard during its cyclic use in the corrugation production process were researched. It has been established that the effect of temperature on cardboard during the corrugated production process significantly reduces the mechanical properties of cardboard during its cyclic processing. So, after the fifth cycle of cardboard processing, exposed to a temperature of 160 ± 5 C for 3 minutes, the tear resistance is 1.6 times lower, the bursting resistance is 2.7 times lower compared to cardboard samples that were not subjected to thermal treatment. In the first four cycles of processing, the destruction of the surface of the fibers probably occurs with a slight decrease in length (1–4%) and a low content of small pieces of cellulose. At the 5th cycle of processing, there is a significant reduction in the length of the fiber by 37%, an increase in coarseness, but it doesn’t lead to a critical decrease in the strength of the cardboard. In the course of the research, it was found that the length of small pieces of cellulose (objects <0.2 mm long) remained unchanged during cyclic use, and the area of the fines steadily increased. The morphological characteristics of cellulose fibers, depending on the cycle of use and temperature effect, changed significantly. The length of the fiber decreased, while the fibers flattened out, became wider and coarser. The number and area of small things increased with each processing cycle, the small things were combined into larger objects. At the same time, the fibers became less deformed, and their alignment took place.