Comparative Adhesive Bonding of Wood Chemically Modified with Either Acetic Anhydride or Butylene Oxide

Abstract

Determining adhesive bond performance for chemically modified wood is important not only for its commercial utility but also for understanding wood bond durability. Bulking modifications occupy space inside the cell wall, limiting the space available for water. We used two bulking modifications on yellow poplar (Liriodendron tulipifera L.): acetylation (Ac), which bulks and converts a wood hydroxyl group to an ester, while butylene oxide (BO) also bulks the wood but preserves a hydroxyl group. Both result in lower water uptake; however, the loss of the hydroxyl group with Ac reduces the wood’s ability to form hydrogen and other polar bonds with the adhesives. On the other hand, the BO reaction replaces a hydroxyl group with another one along a hydrocarbon chain; thus, this product may not be harder to bond than the unmodified wood. We investigated how these chemical modifications of wood affect bond performance with four adhesives: resorcinol-formaldehyde (RF), melamine-formaldehyde (MF), emulsion polymer isocyanate (EPI), and epoxy. The ASTM D 905 bond shear strength for both dry and wet samples showed that the BO results were quite similar to the unmodified wood, but the MF and EPI performed poorly on Ac-modified wood, in contrast to the results with RF and epoxy.

Preparation of Environmentally Friendly Glueless Boxwood Timber by Acidic Environmental Treatment and High-Temperature Pressing

“…Part of the hemicellulose dissolves in aqueous solutions, and part of the hemicellulose is degraded to small molecular sugars by the action of acid; thus, the structure and composition of the remaining hemicellulose is greatly altered after exogenous acid treatment. As the water content increases, the number of hydroxyl groups decreases and moves toward lower wave numbers, indicating that the hydroxyl groups interact to form hydrogen bonds, which increases the bonding force between fibers and facilitates fiber bonding into boards [ 15 , 16 ]. At the same time, the glycosidic bond is broken to produce furfural, which later undergoes a dehydrogenation and polycondensation reaction under a high temperature and pressure to produce part of the furan ring and furan resin, which provides bonding and water resistance [ 17 , 18 ].…”

Effect of NaOH Pretreatment on Permeability and Surface Properties of Three Wood Species

“…Poplar, a common fast-growing broad-leaf wood, is mostly dark yellow and has a loose fiber structure, limiting its use. Researchers have conducted many modification treatments to expand the range of applications for poplar. − Wood pretreatment is a necessary step before various modification treatments of wood, aiming to improve the permeability of wood and reduce the resistance of wood’s anisotropy to the penetration and diffusion of modifying agents. However, there is currently limited research on the pretreatment of cedar, white oak, and poplar with NaOH, especially regarding the effects of NaOH on the quality changes and surface properties of these three types of wood.…”

Comparative Study of Plywood Boards Produced with Castor Oil-Based Polyurethane and Phenol-Formaldehyde Using Pinus taeda L. Veneers Treated with Chromated Copper Arsenate

“…Wood is often described as being essential for mankind, due its large quantity, high renewability and environmentally benign qualities, ease of working and excellent mechanical properties [1,2]. The wood industry has grown across the world because it offers a renewable raw material that is increasingly available on the market.…”

“…Consequently, wood protection has become an essential research field. Commonly, wood can be treated by impregnation methods, such as creosote treatment, and surface alteration, such as chromated-copper-arsenate, (CCA) or copper salt treatments [2].…”

“…In the field of panel production, researchers have developed studies aiming to enhance the durability and obtain better product properties. Thus, the wood modification is a significant area of study, given the benefits of reducing wood swelling, microbial decay and insect attack [2]. Furthermore, the investigation into the sustainable application of renewable resources is crucial for the world, due to growing anthropic activities causing environmental disorders, i.e., climate change, and soil and air pollution.…”