TAPPI Journal summaries.
QUANTIFICATION OF SOFTWOOD, HARDWOOD, AND NONWOOD FIBER CONTENT IN PACKAGING GRADE PAPERS
By Stergios Adamopoulos
APPLICATION: Packaging grade papers incorporate a variety of wood and nonwood fiber types. Manufacturing of papers of consistent and acceptable quality requires knowledge concerning the quantity of each fiber used.
This study determined percentages by weight of the fiber components in 15 papers commonly used to produce corrugating packaging in Spain. The papers are manufactured mainly from recycled raw materials. The percentages were determined by means of standard quantitative fiber analysis techniques and use of appropriate weight factors.
Quantitative fiber composition reflects the differences in quality between the papers. Its usefulness could be further explored in the quality control of paper manufacturing for packaging.
EVALUATION OF FOREST THINNING MATERIALS FOR TMP PRODUCTION
By John H. Klungness, Roland Gleisner, Doreen Mann, Karen L. Scallon, J.Y. Zhu, Eric G. Horn, and Louis L. Edwards
APPLICATION: The results of this study may help mills improve pulp production through better use of potentially neglected fiber resources.
We used SilviScan analysis and tracheid measurement to evaluate the effect of suppressed growth on the fundamental properties of wood fiber. Suppressed growth reduced cell tracheid length, but the high content of mature wood may translate into longer fibers overall. In pilot-scale refining experiments, blending 25% chips from small-diameter trees (SMD) with 75% mill wood chips produced slightly better quality pulp compared with pulp from a control mill wood chip sample. We conclude that suppressed growth trees are superior to normal growth trees for thermomechanical pulp production because of uniformity in cell geometry, thin cell walls, and higher content of mature wood.
OPERATIONAL EVALUATION OF ROTARY DRUM VACUUM FILTERS FOR BROWNSTOCK WASHING USING BASIC FILTRATION PARAMETERS
By Claudio R.F. Pacheco, Jose L. de Paiva, and Antonio S. Reynol, Jr.
APPLICATION: A computer program using these calculations will facilitate
the management of brownstock washing operations.
Process managers rely on information about operational efficiency in their daily routines. Brownstock washing is an operation that relies on accurate control of the washing fluid to conserve energy, decrease water usage, and hold down the expenditure of bleaching chemicals.
The overall goal of these researchers has been to develop a practical calculation procedure in the form of a computer program to give brownstock washing managers more information than what the instrument panel tells them and what they can learn through laboratory work. Calculations were developed for a rotary drum vacuum filter. Equations are presented, and the calculation procedure is outlined in detail.
ATOMIC FORCE MICROSCOPY
CHARACTERIZING THE PORE STRUCTURES OF PAPER COATINGS WITH SCANNING PROBE MICROSCOPY
By Sabina Di Risio and Ning Yan
APPLICATION: Atomic force microscopy can characterize the z-directional pore structure of paper coatings at a high resolution.
The coating of a paper sheet determines many of its final properties. However, there are not many methods for characterizing the structure of the coating, and traditional methods are limited in their capabilities. A new method has now been developed using an atomic force microscope. Atomic force microscopy (AFM) offers higher resolution in analyzing the spatial arrangement of coating components. Samples are prepared by ultramicrotomy, but require no labeling of the coating components.
SUBSTITUTION OF HARDWOOD KRAFT WITH ASPEN HIGH-YIELD PULP IN LIGHTWEIGHT COATED WOOD-FREE PAPERS: PART I. SYNERGY OF BASESTOCK PROPERTIES
By Kaitang Hu, Yonghao Ni, Yajun Zhou, and Xuejun Zou
APPLICATION: Results suggest that the substitution of HBKP with aspen HYP up to 30% is technically feasible and beneficial for producing a lightweight "wood-free" basestock.
Papermakers have shown an interest in using high-yield pulps (HYP) in wood-free coated papers to reduce cost and improve product performance. HYP is essentially a chemimechanical pulp, so there are concerns about the potential effects its use might have on the coating operation and coated paper performance.
To address these concerns, we carried out a systematic investigation on the effects of substituting hardwood bleached kraft pulp (HBKP) with HYP on the properties of basestock, coated, and calendered sheets, with a focus on lightweight coated grades. The results are presented in two reports. In this first part we focus on the potential impact of HYP substitution on basestock properties.