Effects of Hydrogen Peroxide Bleaching and Acetic Anhydride on Photodegradation of Hornbeam CMP Pulp

摘要

In this study, the effects of hydrogen peroxide bleaching and acetic anhydride as acetylation agent on photo degradation of hornbeam CMP pulp investigated. Hornbeam chips pulped under CMP conditions at the yield of 85 %. Then, one portion of pulp was bleached using hydrogen peroxide and DTPA as chelating agent and 60 gr handsheets were made from bleached and unbleached pulp. A number of unbleached handsheets were acetylated using acetic anhydride at 80 °C for 30 and 60 min. The handsheet were irradiated for 10, 20, 30 and 40 min for accelerated aging. The optical characteristics of the handsheets were measured before and after optical aging. The results showed that following bleaching and aceetylation, absorption coefficient, K/S ratio, opacity, yellowness, greenness and post colour number were decreased and brightness was increased. Acetylated handsheets, especially those acetylated for 60 min, have better brightness stability and less brightness reversion.