Cell Wall Bulking by Maleic Anhydride for Wood Durability Improvement

Abstract

Wood is susceptible to swelling deformation and decay fungi due to moisture adsorption that originates from the dynamic nanopores of the cell wall and the abundant hydroxyl groups in wood components. This study employed as a modifier maleic anhydride (MAn), with the help of acetone as solvent, to diffuse into the wood cell wall, bulk nanopores, and further chemically bond to the hydroxyl groups of wood components, reducing the numbers of free hydroxyl groups and weakening the diffusion of water molecules into the wood cell wall. The derived MAn-bulked wood, compared to the control wood, presented a reduction in water absorptivity (RWA) of ~23% as well as an anti-swelling efficiency (ASE) of ~39% after immersion in water for 228 h, and showed an improvement in decay resistance of 81.42% against white-rot fungus and 69.79% against brown-rot fungus, respectively. The method of combined cell wall bulking and hydroxyl group bonding could effectively improve the dimensional stability and decay resistance with lower doses of modifier, providing a new strategy for wood durability improvement.

Preparation of Wood-Based Panel Composites with Poplar Veneer as the Surface Layer Modified by In-Situ Polymerization of Active Monomers

“…The MOR and MOE were evaluated by the three-point bending method, according to the GB/T 17657-2013 [31,32]. In brief, the sample was put on two support points of the hot press (Harbin Dongda Artificial Board Machinery Manufacturing Co., Ltd., Harbin, China) with a full range of 100 tons and a hot-pressing area of 420 mm × 420 mm.…”

Hydrophobization and Photo-Stabilization of Radiata Pinewood: The Effect of the Esterification on Thermal and Mechanical Properties

“…The results show that WPG was not only influenced by the concentration but also by the chain length of the fatty acid chlorides and the moisture content of samples at 65% RH and 25 • C. This connection was evident in treatments at [0.5 M], suggesting the following rate of reaction according to WPG on each treatment: P6 > P12 > P18. One condition that affected physical properties was the number of carbons in the aliphatic chain, which was related to the steric hindrance originating from neighboring substituents in the active sites of wood and could be represented in terms of WPG [7,8,12]. Initially, the number of OH groups available was higher, but once the accessible groups of the surface were modified, the diffusion of the esterification agent in the wood cell wall slows down the reaction rate and, consequently, WPG.…”

“…For this experiment, all treatments lasted for 3 h; however, it is expected that changes in reaction time will lead to different WPGs and, therefore, influence wood properties. For a better understanding of the effect of reaction time on wood properties, it was necessary to perform extended tests at different reaction times in order to experimentally find with greater precision the optimal point for each of the esterification reagents used [6][7][8]. Moreover, at lab conditions (65% RH and 25 • C), the moisture content of each esterified sample and concentration was inversely correlated with WPG, where higher MC lowered the physical properties.…”

“…In addition, the esterification reaction also results in bulking of the wood cell wall generated by the groups grafted onto the matrix [7]. The main advantage of the ester bond in wood is the reduction of its natural hydrophilic character, thus avoiding excessive moisture absorption, which in turn increases the dimensional stability and delays the arrival of decay agents into the wood [8,9]. Moreover, the functionalization of phenolic hydroxyl groups of lignin present in wood prevents the formation of phenoxy radicals and enhances the wood's UV resistance [10].…”

Wood Productions and Renewable Materials: The Future Is Now

“…Wood protection can be achieved through wood modification. Impregnation is a wood modification technique that has existed for many years, but the use of new impregnation products such as maleic anhydride can lead to significant reduction of wood's moisture sensitivity [9].…”