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Four types of industrial waste from wood processing, namely a mixed hardwood-softwood powder, pine and beech sawdust, and bark were liquefied and tested as binders for particleboards (PB) made of recycled wood. The liquefaction reaction was carried out at elevated temperature with a mixture of solvents from polyhydroxyl alcohols such as glycerine and propylene glycol, and p-toluenesulfonic acid as a catalyst. Then the liquefied woods (LWs) were characterized in terms of their suitability for PB production as a partial substitute for synthetic urea-formaldehyde (UF) resin. The standard properties of PBs such as tensile strength, bending strength and modulus of elasticity, density, moisture content, swelling after 24 h, water absorption, and formaldehyde content were measured. All tests were performed in comparison to a standard PB bonded by UF resin. It was demonstrated that the substitution of UF resin up to 20% of LW did not have a significant effect on the mechanical properties. PB made of recycled wood produced with LW possessed good mechanical properties that meet the European standard quality demands for PBs. [ABSTRACT FROM AUTHOR]

The valorization of lignocellulosic biomass for the manufacturing of value-added materials is a fundamental pillar of sustainable development and circular economy, providing an alternative to petroleum-based refineries and contributing to green transition in production. Lignocellulosic biomass is a valuable source of components and can be utilized to produce biopolymers via chemical, physical, microbiological, or enzymatic routes. Fractions obtained from the lignocellulosic biomass can be used in suitable and specific applications. Currently and primarily, wood is a raw source of nanocellulose production. In the interest of the diminishing wood resources in the world, the nanocellulose can be extracted from the lignocellulosic biomass, including waste biomass. In turn, liquefaction can be adopted as one of the effective methods of lignocellulosic waste management. The presented study focused on the different aspects of synthesis, modification, and applications of biopolymers obtained from lignocellulosic biomass, such as nanocrystalline cellulose (CNC), nanofibrillated cellulose (CNF), and liquefied wood. The research aimed to valorize the lignocellulosic biomass for the production of biopolymers intended to use in adhesives and wood composite materials. Firstly, the potential of lignocellulosic biomass to form biopolymers was discussed. Furthermore, different methods for biomass pre-treatment were explained. The need for nanocellulose modification was highlighted to improve the functionality of the materials. Finally, the application of both kinds of nanocellulose and liquefied wood were explored in the field of the wood-based panel sector. Nanocellulose was effectively recovered, and liquefied wood was successfully obtained from lignocellulosic biomass, which was confirmed by microscopic examination. Nanocellulose acted as modifying and reinforcing agent of amine resins improving mechanical performance and reducing formaldehyde emission. On the other hand, replacing 40% of the standard amino resin with liquefied wood caused that the minimum requirements for particleboards of type P2 according to PN-EN 312 has been met. [ABSTRACT FROM AUTHOR]

This work presents the characteristics of wood liquefied using different types of solvents in terms of its application for binding particleboards. Standard pine particles from barked wood were used for the liquefaction experiments. The liquefaction reaction was carried out in high temperature conditions using a mixture of solvents from the polyhydroxy alcohol group, including glycerine, ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol. The microstructure of both the liquefied wood and the liquefaction residues was determined by means of optical microscopy analysis. The basic parameters of the adhesive mixture modified with the liquefied wood, such as viscosity, pH and gel time were determined. Particleboards containing liquefied wood were produced. The following physicochemical and mechanical properties of the particleboards were measured: tensile strength, bending strength, modulus of elasticity, and formaldehyde content. The influence of the liquefying agent on the board properties was investigated. In all the tests, a control particleboard, bonded with a urea-formaldehyde adhesive resin with no inclusion of liquefied wood, was used for the purposes of comparison. [ABSTRACT FROM AUTHOR]