WOOD RESEARCH Volume 68, Number 1, 2023
Joanna Walkiewicz, Jakub Kawalerczyk, Radosław Mirski, and Zuzanna Szubert

Short notes: The tea leaves as a filler for UF resin plywood production

The addition of green tea leaves fractions < 0.315 mm as a filler to urea-formaldehyde resin to reduction of emission of formaldehyde from three-layer birch plywood was investigated. Moreover, other properties such as bonding quality and water resistance of plywood were investigated. It was found that green tea had an ability to absorb formaldehyde. This phenomenon was caused by phenolic compounds contained in green tea leaves. The addition of green tea in the amount of 20% and 25% resulted in a decrease in formaldehyde emission from plywood comparing to the reference sample. The bonding quality test showed that the addition of tea leaves as a filler did not affect the strength properties of the tested bond lines.

WOOD RESEARCH Volume 67, Number 5, 2022
Jakub Kawalerczyk, Dorota Dziurka, and Radosław Mirski

The effect of a phenol-formaldehyde adhesive reinforcement with nanocellulose on the pressing parameters of plywood

Research on improving the reactivity of phenol-formaldehyde (PF) resin and the possibility of lowering the pressing parameters of wood-based materials manufactured with its participation are still progressing. Due to a number of favorable properties, nanocellulose (NCC) is gaining more and more popularity as a modifier of wood adhesives. Therefore, the objective of the study was to assess the possible reduction of plywood pressing parameters due to the reinforcement of PF resin with NCC. Based on the bonding quality results it was found that there is a possibility to reduce pressing time by 25% and pressing temperature by 7%. Moreover, the outcomes of mechanical properties (modulus of elasticity and bending strength) of manufactured plywood indicate that theoretically it could be possible to decrease the pressing parameters even more. However, the shear strength of the glue joints was considered to be a limiting factor for further reduction. The results of delamination test show that plywood bonded with phenolic resin have no tendency to delaminate. Thus, it can be concluded that NCC can be used as a modifier for PF resin which can contribute to the reduction of pressing time and pressing temperature during the plywood manufacturing process.

WOOD RESEARCH Volume 66, Number 6, 2021
Radosław Mirski, Aleksandra Banaszak, Ewa Fabisiak, and Joanna Siuda

Anatomical properties of straw of various annual plants used for the production of wood panels

The aim of this study was to determine basic anatomical features of annual plant fibers used as wood substitutes for the production of wood-based panels. For this purpose rye, wheat, triticale, rape and corn straw were used. The determination of the morphological features of the fibers was conducted on the macerated material. Fiber lengths, fiber diameters and lumens were measured, and then the fiber wall thicknesses and slenderness ratios were calculated. The result clearly showed significant differences among all fiber characteristics of the tested plants. The strength and direction of the relationship between the anatomical properties determined in the study and the physicomechanical properties of the boards produced with straw from the tested annual plants were identified.

WOOD RESEARCH Volume 66, Number 6, 2021
Jakub Kawalerczyk, Joanna Siuda, Dorota Dziurka, Radosław Mirski, Magdalena Woźniak, and Kinga Stuper-Szablewska

The soy flour as an extender for uf and muf adhesives in birch plywood production

Formaldehyde emission still remains a major disadvantage of widely applied formaldehyde-containing amino resins such as UF (urea-formaldehyde) resin and MUF (melamine-urea-formaldehyde) resin. The compositions of adhesives for plywood manufacturing have to contain a proper extenders in order to adjust their viscosity. Thus, the aim of the study was to investigate the effect of protein-rich soy flour (SF) as the extender for adhesives. The composition of flours and their ability to absorb the formaldehyde were determined. Properties of liquid resins such as gel time, viscosity, pH and solid content were investigated. The possible chemical interaction between the extenders and resins were assessed with the use of FTIR spectroscopy. Plywood panels manufactured using UF and MUF adhesives with the soy flour introduced as the extender in various concentrations were tested in terms of shear strength and formaldehyde release. Studies have shown that soy flour has a favorable composition and formaldehyde-scavenging ability. The addition of SF affected resins properties such as viscosity and gel time but showed no influence on their pH and solid content. FTIR analysis has not explained the chemical interaction between resin and extender. The application of soy flour in the concentration of 15% for UF resin and 10% for MUF resin allowed to produce plywood characterized by improved bonding quality and decreased formaldehyde emission.

WOOD RESEARCH Volume 64, Number 4, 2019
Radosław Mirski, Dorota Dziurka, and Aleksandra Banaszak

Effects of manufacture conditions on physical and mechanical properties of rape-polymer boards

The paper presents a method of manufacturing boards composed of lignin-cellulose chips and thermoplastic polymers (waste-based particle polymer composites, WPPC) by means of flat pressing. Rape chips, similar in size to wood chips in traditional particleboards, served as filling material, and polyethylene and polypropylene made up the outer layers. The polymers enriched only the external layers, as this allowed for considerable shortening of pressing time. The resulting boards featured satisfactory properties as compared with control, not polymer covered boards. Our study identified a temperature of 220°C and low moisture content of the polymer-containing layers as favorable for production of this type of boards. We also found out that using a sublayer with higher moisture content not only shortened the pressing time, but also improved the board properties evaluated by a bend test.