Sodium hydroxide (NaOH) has been used as an alkali source in conventional hydrogen peroxide bleaching. In the present work, partial and total replacement of NaOH with magnesium hydroxide (Mg(OH)2) as the alkali source for hydrogen peroxide bleaching of deinked pulp was studied. The bleached pulp was studied with respect to brightness, post color (P.C.) number, and mechanical properties (i.e., t...

raft pulp i s manufactured in the United States from nearly all commercially availK ble wood species. About 55 million tons per year are manufactured, 30 million of which are bleached and used mostly for printing and office papers and tissue products. Some kraft pulp is exported, and significant quantities are imported, mostly from Canada and South America. Pulps manufactldred by sulfite, mecha...

As part of a program to reduce electrical energy consumption in the refining process, the effects of the ozone and alkaline peroxide treatments on fibre and handsheet properties, prior and subsequent to low consistency (LC) refining, were assessed and compared by applying different levels of ozone and a range of peroxide and alkali charges to a primary stage hemlock thermomechanical pulp (TMP)....

Cellulose nanofibers can be produced using a combination of TEMPO, sodium bromide (NaBr) and sodium hypochlorite, and mechanical dispersion. Recently, this process has been the subject of intensive investigation. However, studies on the aspects of mechanical treatment of this process remain marginal. The main objective of this study is to evaluate the high shear dispersion parameters (e.g., con...

To reduce the refining energy consumption of chemi-mechanical pulping, treatment with NaOH-thiourea-urea aqueous solution was studied in this work. By means of single-factor experiments, the effects of alkali dosage, soaking time, and freezing time were evaluated. It was found that the optimal conditions were an alkali dosage of 8%, soaking time of 45 min, and freezing time of 105 min. The resu...

OBJECTIVES So far, bovine immortalized pulp cells have been used as three dimensional cultures for cytotoxicity testing of filling materials in the dentin barrier test (DBT). In this study, the use of human pulp-derived cells was evaluated, which would better simulate the clinical situation, and a composite material with a new resin base was tested. MATERIALS AND METHODS SV40-transfected huma...

Supercritical carbon dioxide extraction (scCO2) is chosen to a treatment to remove lignin and to peel off outer cell wall layers to expose S2 layer of aspen wood fibres. The aim is to find an effective and environmentally friendly method to advance the fibrillation of the BCTMP pulp. The effects of the treatment are analysed by using scanning electron microscopy (SEM). The chemicals used togeth...

Recycling and deinking processes cause fiber damage because of hornification phenomena and increased external fibrillation. Mechanical refining has been used for many years to enhance the mechanical properties of paper. Biorefining of pulp using enzymes is receiving increasing interest for energy reduction at the refining step of the papermaking process. Moreover, enzymes have also been used fo...

Recent advances in imaging technology have made it possible to capture three-dimensional (3D) images of pulp fibre based materials with high resolution (Antoine et al. 2002). This methodology can also be used for fibre-based composite materials. Analysis of such images can provide very detailed knowledge about the microstructure of the material, which in turn controls the mechanical properties....