Changes in wood fibre chemistry during the stages of recycling.

摘要

In the last decade, radical changes have taken place in Ontario's papermaking industry. Public demand has led to the establishment of a host of recycled paper mills in the southern half of the province, all of which must compete for a limited supply of old newsprint and magazines for feedstock. Thus, process efficiency is a key concern for recycled paper manufacturers. The goal of this study was to examine the efficiency of the recycling process from the standpoint of wood chemistry. Three mills in Southern Ontario were chosen for the project, and samples were obtained from each of these mills before and after the refining, deinking, and sheet formation stages of recycled paper production. The levels of cellulose, hemicellulose, and lignin were measured in each of these sample groups, as were the amounts of extractable materials and trace elements. The fibres from each sample were examined visually in order to correlate results. A statistical analysis was carried out to determine if significant chemical changes had taken place between each stage of the recycling process. It was found that wood chemistry is altered by the deinking and/or sheet formation stages to the greatest degree, followed by the deragging (or refining) stages. Significantly lower percentages of lignin in the final product indicate that material has been lost, leaving greater amounts of cellulose and hemicellulose. These losses have been attributed to the physical degradation associated with the sheet formation process.