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 69, Number 2, 2024
VLADIMÍR IHNÁT, HENRICH LÜBKE, ALBERT RUSS, JOZEF BALBERČÁK, VLADIMÍR KUŇA, ANDREJ PAŽITNÝ, and ŠTEFAN BOHÁČEK

LIGNOCELLULOSIC LINERS BASED ON WOOD WOOL

Basic physical and mechanical properties of lignocellulosic liners up to 1.5 mm thick with a compact and non-crumbling surface based on wood wool and thermoplastic water based glues were determined. PVAc and starch glue with a high proportion of water content were used. The dry mat was pressed gradually under high pressure up to 28 MPa and a temperature of around 190°C with the release of steam. Tests according to the CEPI (Confederation of European Paper Industries) standards were adopted. Procedures for tensile strength according to ISO 1924-2 (2008), Burst strength according to ISO 2758 (2014), puncture according to ASTM D781-68 (1973), water absorption according to ISO 5637 (1989) and porosity according to TAPPI Test method T460 were applied

WOOD RESEARCH Volume 69, Number 2, 2024
ŠTEFAN BOHÁČEK, VLADIMÍR KUŇA, JOZEF BALBERČÁK, and ALENA JANDOVÁ

INCREASING THE EFFICIENCY OF ENZYMATIC HYDROLYSIS OF LIGNOCELLULOSIC MATERIALS BY FREEZING PRETREATMENT

This paper describes the differences between the efficiency of enzymatic hydrolysis of selected lignocellulosic materials after pretreatment by cyclic freezing and thawing. It also discusses the analysis of the positive effect of alkaline conditions on pretreatment. The selected materials were Populus alba L., wheat straw from Triticum aestivum L. and Cannabis sativa. Three pretreatment methods were used to compare the efficiency of enzymatic decomposition of cellulose and cellulose accessibility. The best results show the wheat straw pre-treated at -20°C in the freezer with NaOH addition with a concentration of monosaccharides of 56.6 g.l-1 compared to initial hydrolysed material with a concentration of monosaccharides of 24.4 g.l-1. The results show better digestibility of grass compared to wood dendromass

WOOD RESEARCH Volume 69, Number 1, 2024
VLADIMÍR IHNÁT, HENRICH LÜBKE, RASTISLAV ČEREŠŇA, JOZEF BALBERČÁK, VLADIMÍR KUŇA, ANDREJ PAŽITNÝ, and ŠTEFAN BOHÁČEK

THIN LIGNOCELLULOSIC LINERS BASED OF SPRUCE SHAVINGS

The article is devoted to determining the basic physical and mechanical properties of sheet materials up to 1.5 mm thick based on wood shavings and PVAc glue with a high proportion of water, pressed under high pressure up to 25 MPa and a temperature of around 190°C, so that the softening of lignin caused by the generated steam, allow to create a compact and non-crumbling surface. In order to characterize the physical-mechanical properties of the new wood-based sheet material with minimum thickness and characteristic elasticity, tests according to the CEPI (Confederation of European Paper Industries) standards were adopted. Procedures for tensile strength according to ISO 1924-2 (2008), Burst strength according to ISO 2758 (2014), puncture according to ASTM D781-68 (1973), water absorption according to ISO 5637 (1989) and porosity according to TAPPI Test method T460 were applied

WOOD RESEARCH Volume 69, Number 1, 2024
JOZEF BALBERČÁK and VLADIMÍR KUŇA

MODIFIED STARCHES AS A MEAN OF INCREASING THE DRY STRENGTH OF TISSUE PAPERS

Application of agents to increase the dry strength is one of the ways of improving the physical-mechanical properties of papers. In the presented article, we are dealing with the application of modified starches to the pulp mass in order to increase the strength parameters of hygienic papers. In laboratory experiments, 8 types of agents were tested, which differed in charge level, molecular weight and cross-linker level. Strength parameters, porosity and water absorption were evaluated during the laboratory tests. The most important strength parameter in the production of tissue papers is the tensile strength, the most suitable parameters for the production of tissue papers were achieved when applying the product ECO 2777. By monitoring the influence of the dose of starch, it was found that the optimal dose is 3 kg per ton of absolutely dry pulp, when there is an increase in the tensile strength by 18%, the burst strength by 41% and while maintaining the required values of stiffness, porosity and water absorption