WOOD RESEARCH Volume 70, Number 4, 2025
VLADIMÍR KUŇA and JOZEF BALBERČÁK

THE INFLUENCE OF PULP BEATING AND PAPERMAKING AGENTS ON THE CHARGE DENSITY OF FIBERS AND COLLOIDAL PARTICLES IN PAPERMAKING WATERS

The first part of the paper is focused on monitoring the impact of the beating process on the charge density of fibres and colloidal particles in water in the production of tissue papers. Three types of pulps most commonly used were tested: long-fibre pine pulp, short-fibre eucalyptus pulp and short-fibre hardwood birch pulp. In the range of beating degrees from 14°SR to 35°SR, the impact of beating on the charge density of fibres expressed as Zeta potential, the charge density of colloidal particles expressed as PCD value and the conductivity of the paper suspension were evaluated. The paper also evaluates the impact of beating on the physical and mechanical properties of laboratory sheets. The second part of the paper is focused on monitoring the impact of papermaking aids, in the production of tissue papers, on the charge density of fibres and colloidal particles in water. The most significant impact was demonstrated by the agent for increasing the wet strength of paper. In these laboratory tests, pulp mixtures were used that were prepared by separately beating individual pulps to a beating degree of 25°SR.

WOOD RESEARCH Volume 61, Number 1, 2016
Birol Üner, Mehmet Akgül, M.Onurhan Gücüş, and Serkan Demir

The effect of oxalic acid pretreatment on alkali pulping process

The objective of this study was to determine prehydrolysis process on kraft and soda pulping process. Optimum cooking conditions were determined by different alkali concentration and cooking period. Oxalicacid was used to hydrolyzechip before cooking. Prehydrolysis proces increased the yield and viscosity of pulp. Incontrast, mechanical properties of paper were not changed significantly. Optical properties were decreased due to lignin content.

WOOD RESEARCH Volume 63, Number 6, 2018
Jiajun Wang, Junliang Liu, Lin Ni, and Jianzhang Li

Thermopressed binderless fiberboards from wheat straw by adding black liquor

For the shortage of timber resources and the sake of the formaldehyde emissions, people desire to use non-adhesive bonding technology. This paper studies the chemical composites of black liquor, at different contents ranging from 20 to 40 wt%, into fiberboards made from wheat straw pulp. Adding a little black liquor has positive effect on qualities of boards, contributing to presence of proteins and lignin in black liquor, but adding too much liquor would decrease properties of them for the ash content. The FT-IR measurements indicated that there are more low-molecular substance and hydrogen bonds producing after fining and thermopressing processes. The thermo analysis were conducted to better understand these results. The physical and mechanical properties of the resulting fiberboard were evaluated. The results showed that binderless fiberboards by adding 30 wt% have good mechanical and water resistance properties which can partly satisfy the requirements of the relevant standards specifications.

WOOD RESEARCH Volume 63, Number 4, 2018
Partson Tinarwo, Temesgen Zewotir, and Delia North

Pre-hydrolysis pulping process optimization with multiple response surface modelling

Three properties of dissolving pulp namely lignin, viscosity and the α-cellulose were investigated. A laboratory experiment for the dissolving wood pulping process was conducted on nine Eucalyptus genotypes: Edunnii, Esmithii, Egrandis, Macarthurii, Emearnsii, Enitens, GCG438, GUA380 and GUW962. Repeated measurements were taken at each of the six processing stages for the changes in lignin, viscosity and the α-cellulose. A response surface approach was used to select the best genotype for each property and further application of desirability analysis to identify the genotype that simultaneously gives the best results for the three properties. The predictive models and associated statistical tests proved that all the nine genotypes were capable of producing the optimal results (>95.55% α-cellulose) although a few were at the thresholds of the feasible region. The optimisation process also revealed that the genotype Emearnsii possesses the most desirable properties for the α-96 cellulose product output and Enitens consistently produces results within the desired range. The use of simultaneous desirability functions indicated that the overall product quality characteristics for lignin, viscosity and the α-cellulose can be improved by steadily excluding the most resistant genotypes to lignin reduction, especially Edunnii and Esmithii.

WOOD RESEARCH Volume 63, Number 3, 2018
VLADIMÍR IHNÁT, HENRICH LÜBKE, ALBERT RUSS, Pažitný Andrej, and Vlastimil Borůvka

Waste agglomerated wood materials as a secondary raw material for chipboards and f ibreboards Part II. Preparation and characterisation of wood f ibres in terms of their reuse

The paper describes a process for the preparation of fibre from waste wood particleboards (PB), oriented strand chipboard (OSB) and medium density fibreboard (MDF). The purpose of recycling of agglomerated wood materials is to reuse them for the production of fibrous materials. The agglomerated materials disintegrated after the initial destruction were further processed under the specified conditions with respect to the moisture content, their type, adhesive used, and properties of final particles – wood chips. The obtained wood particles were characterized by the fractional composition of chips. The resulting chips were mechanically defibred with subsequent characterization of fiber obtained for its reuse in the manufacture of MDF. A quantity of formaldehyde released into the water when cooking waste MDF and PB was set up depending on the cooking time. Residual level of formaldehyde is the main chemical load that determines the amount of waste material that can be reused for production of new panels based on ureaformaldehyde adhesives.

WOOD RESEARCH Volume 65, Number 3, 2020
Ivana Plazonić, Željka Barbarić-Mikočević, and Nikola Španić

Effect of agricultural residue fibers on newsprint strength properties

As newsprints, mostly made from recycled wood pulp, are not high quality papers according to its optical, mechanical and chemical characteristics, in this research the usage of straw pulp as an alternative raw material was analyzed. For that purpose, straw pulp was mixed with recycled wood pulp and strength properties of laboratory made papers were determined according to TAPPI standards. Selection of agricultural waste for preparing straw pulp was based on annual yield of crop species (Triticum spp., Hordeum vulgare L. and Triticale sp.). Results indicated that straw pulp can be efficiently used in portions up to 20% as a substitute for wood fibers or as an additive in order to obtain particular newsprint properties.

WOOD RESEARCH Volume 64, Number 3, 2019
RIZKI ARISANDI, Sri Nugroho Marsoem, GANIS LUKMANDARU, Tatsuya Ashitani, and Koetsu Takahashi

The contents of phenolics and cell wall component of Eucalyptus pellita F. Muell stemwood and bark

Eucalyptus pellita is the fast-growing species which is being developed for a raw material of pulp and paper in Indonesia. The aim of this research was to evaluate the total phenolics (TPC) and flavanols contents (TFC) in the stemwood and bark parts from four individual trees. Another purpose was to determine its cell wall contents. Wood and bark materials in two vertical positions (bottom and top) were successively extracted using dichloromethane, ethanol and hot water as the solvents. Axial factor affected significantly in the values of hot water extract, TPC, and TFC but no significantly affected the cell wall component contents. The ethanol extract levels in the heartwood part was the significantly highest. It is noticed that the heartwood part had high levels of the TPC and TFC and low level in lignin content. From this experiment, the comparatively high levels of TPC and TFC in the heartwood indicate the potential antioxidative properties that should be explored in the future. Further, the low content of Klason lignin in the heartwood part would be an advantage for pulp production.