Sustainable Development Approaches through Wooden Adhesive Joints Design

Abstract

Over recent decades, the need to comply with environmental standards has become a concern in many industrial sectors. As a result, manufacturers have increased their use of eco-friendly, recycled, recyclable, and, overall, more sustainable materials and industrial techniques. One technique highly dependent on petroleum-based products, and at the edge of a paradigm change, is adhesive bonding. Adhesive bonding is often used to join composite materials and depends upon an adhesive to achieve the connection. However, the matrices of the composite materials and the adhesives used, as well as, in some cases, the composite fibres, are manufactured from petrochemical products. Efforts to use natural composites and adhesives are therefore ongoing. One composite that has proven to be promising is wood due to its high strength and stiffness (particularly when it is densified), formability, and durability. However, wood must be very carefully characterised since its properties can be variable, depending on the slope of the grains, irregularities (such as knots, shakes, or splits), and on the location and climate of each individual tree. Therefore, in addition to neat wood, wood composites may also be a promising option to increase sustainability, with more predictable properties. To bond wood or wooden composite substrates, bio-adhesives can be considered. These adhesives are now formulated with increasingly enhanced mechanical properties and are becoming promising alternatives at the structural application level. In this paper, wooden adhesive joints are surveyed considering bio-adhesives and wood-based substrates, taking into consideration the recent approaches to improve these base materials, accurately characterise them, and implement them in adhesive joints.

A Novel Technique for Substrate Toughening in Wood Single Lap Joints Using a Zero-Thickness Bio-Adhesive

“…Also, the density of the toughened samples was measured after the curing process of the bio-adhesive. The results indicated that the average density of the reference wood was 0.56 ± 0.03 g/cm 3 and that the bio-adhesive increased the wood density by 4%.…”

“…The recent concerted drive towards reducing the impact of fossil-based products has spurred the development and increasingly larger adoption of bio-based materials [1][2][3]. This endeavor seeks to usher in a more sustainable era, where the utilization of tree and plant-derived products assumes a pivotal role.…”

“…In adhesive joints involving wood substrates, the contribution of peel loading is particularly concerning, since it leads to delamination between distinct grain layers and ultimately causes joint failure. To counteract this issue, multiple corrective approaches have been proposed, such as wood densification, substrate toughening, and even physical modifications of the adhesive [3]. These processes aim to tackle the challenge of delamination and bolster the integrity of the adhesive and the wood substrate.…”

From fundamental concepts to recent developments in the adhesive bonding technology: a general view

“…A very recent review on bio-adhesives and their use in wooden adhesive joints can be found in Ref. [44].…”

Update of the Journal “Aims & Scope”

“…The worldwide demand for sustainability and green economy leads to significant research interest in the field of biomacromolecular technology in different directions. These include the replacement of fossil-derived polymers with neat biomacromolecules or their derivatives, the use of green synthesis processes in order to recover and/or synthesize monomers derived from renewable resources, and the production of novel eco-friendly, biodegradable polymers based on these monomers [2]. Eco-friendly processes to recover bio-based monomers from biomass and bio-based polymer recycling methods are also of great interest.…”