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
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.