The woodworking industry generates a great amount of bark which has not yet found a wider industrial application. None of the previously conducted research has considered oak bark application (which is one of the most often processed wood species in Poland) as a filler for wood adhesives. Moreover, no studies have determined the properties of bark containing melamine-urea-formaldehyde resin (MUF), which increasingly replaces pure urea-formaldehyde adhesives. Thus, the aim of the study was to determine the possibility of grinded oak bark application as a filler for MUF adhesive in plywood manufacturing. The chemical composition of oak bark was evaluated. Properties of liquid resins, such as viscosity, gel time, pH, and solid content, were determined. Chemical interaction between the filler and resin was assessed with using Fourier-transform infrared (FTIR) spectroscopy. Plywood panels manufactured using MUF adhesive filled with different bark concentrations (10%, 15%, 20%, 25%) were tested in terms of such properties as formaldehyde release and bonding quality. Studies have shown an improvement in liquid resin properties. The course of FTIR spectra did not explain the chemical interaction between the polymer and the filler. The addition of oak bark at a concentration of 15% made it possible to produce plywood panels characterized by reduced formaldehyde release and improved bonding quality.

This work examines the possibility of applying non-modified nanocellulose and nanocellulose functionalized with 3-aminopropyltriethoxysilane (APTES) as a formaldehyde scavenger for commonly used urea-formaldehyde (UF) adhesive. The effect of silanization was determined with the use of Fourier transform infrared spectroscopy (FTIR), flame atomic absorption spectrometry (FAAS), and elemental analysis. Moreover, the ability of cellulosic nanoparticles to absorb the formaldehyde from an aqueous solution was investigated. After homogenization, cured UF adhesives were examined with the use of FTIR, energy-dispersive spectroscopy (SEM-EDS), and the perforator method to determine the content of formaldehyde. Manufactured boards made of rape straw particles and wood particles were tested in terms of their physico-mechanical properties and formaldehyde emission. Studies have shown that the applied method of silanization was effective. Furthermore, in the case of non-modified nanocellulose, no sign of formaldehyde scavenging ability was found. However, the functionalization of cellulosic nanoparticles with APTES containing an amino group led to the significant reduction of formaldehyde content in both the aqueous solution and the UF adhesive. The mechanical properties of both strawboards and particleboards were improved due to the nanocellulose reinforcement; however, no effect of silanization was found. Nevertheless, functionalization with APTES contributed to a decrease in formaldehyde emission from boards, which was not found in the case of the introduction of non-modified cellulosic nanoparticles.

It can be found that reaction mechanisms and interactions between wood and organosilicone compounds have not been sufficiently explored. The aim of the study was to determine bonds formed between either cellulose or lignin and methyltrimethoxysilane (MTMOS) during a catalytic silanization reaction. Silanization was performed in the presence of two catalysts of a diverse mechanism of functionalization: aluminum acetylacetonate (Al(acac)₃) and acetic acid (AcOH). For this purpose, FT-IR, ¹³C and ²⁹Si NMR techniques were used. Cellulose silanization efficiency without a catalyst was unlikely. Lignin undergoes a silanization reaction with alkoxysilanes much easier than cellulose. The results showed new bonds between biopolymers and the silanising agent. The new bonds were confirmed by signals at the FT-IR spectra, e.g., 770 cm⁻¹ and 1270 cm⁻¹ (Si–CH₃), and at the NMR signal coming from the T¹, T² and T³ structures. Efficiency of reaction was confirmed by atomic absorption spectroscopy (AAS) analysis.

The possibility of using hemp flour as a filling material for melamine-urea-formaldehyde (MUF) adhesive was investigated for the process of manufacturing plywood. Adhesive mixtures were filled with various amounts of hemp flour and compared to rye flour as a reference mixture, and their properties were tested. The quantity of added filler had a significant effect on the resins viscosity. Moreover, the replacement of rye flour with the hemp flour resulted in acceleration of gel time and a slight increase in solid content. Due to the high proteins content, hemp flour led to a significant reduction of formaldehyde emission. Bonding quality of plywood made with hemp flour as a filling material for the adhesive mixture meet the requirements from the standard. Introducing it in an amount of 20 pbw and 25 pbw (parts by weight) allowed for the production of plywood characterized by equally good mechanical properties as that of reference plywood glued with an adhesive mixed with rye flour. In summary, the proper amounts of hemp flour can be applied as a filling material and formaldehyde scavenger for MUF adhesive without the deterioration of mechanical properties of manufactured plywood.

In this study, the possibility of using sawdust, a by-product of primary wood processing, as a filler (WF) for rigid polyurethane (PUR) foams was investigated. The effects of the addition of 5, 10, 15 and 20% of WF particles to the polyurethane matrix on the foaming process, cell structure and selected physical-mechanical properties such as density, thermal conductivity, dimensional stability, water absorption, brittleness, compressive and bending strengths were evaluated. Based on the results, it was found that the addition of WF in the amount of up to 10% does not significantly affect the kinetics of the foam foaming process, allowing the reduction of their thermal conductivity, significantly reducing brittleness and maintaining high dimensional stability. On the other hand, such an amount of WF causes a slight decrease in the compressive strength of the foam, a decrease in its bending strength and an increase in water absorption. However, it is important that in spite of the observed decrease in the values of these parameters, the obtained results are satisfactory and consistent with the parameters of insulation materials based on rigid PUR foam, currently available on the market.

This study examined the effect of applying cellulose nanoparticles as a filling material for phenol-formaldehyde (PF) resin in the process of manufacturing water-resistant plywood. Based on investigations that concerned the rheological behavior of resin mixture containing various amounts of nanofiller, the modification of resin resulted in a major increase of viscosity. Although Fourier transform infrared spectroscopy did not fully explain the effect of modification on the chemical structure of the adhesive, there was a noticeable improvement in the morphology of cured nanocellulose-reinforced resin. Based on the bonding quality results, the optimum amount of nanocellulose was 3 PBW (parts by weight) per 100 PBW of resin and it allowed the achievement of a notable increase in shear strength values. Moreover, introduction of cellulosic nanoparticles had a positive effect on mechanical properties such as bending strength and modulus of elasticity. In summary, the research showed that it is possible to apply nanocellulose as a modifier for the adhesives in the process of manufacturing water-resistant plywood.