Effect of Linear Chain Carboxylic Acid Anhydrides on Physical and Mechanical Properties of Rubber (Hevea brasiliensis), Acacia, (Acacia spp.), and Oil Palm (Tinnera spp.) Woods
The physical and mechanical properties of Rubber wood, Acacia wood, and Oil palm wood that reacted with acetic, propionic, and butyric anhydrides using a microwave heating for 4 minutes were investigated. A sample dimension of 300？mm？×？100？mm？×？25？mm ( ) was used for modification and they were cut into smaller specimens for different testing method. This study found that the density increment and void volume changes were not significantly different from anhydrides. The modification of wood with anhydrides was not significantly affected by the static bending properties, except for the Oil palm. The compression strength for any anhydrides shows an improvement for the Rubber wood and Acacia spp. but not Oil palm. The hardness was also not significantly different from anhydrides for all wood species. The impact strength of Rubber wood and Oil palm significantly increased compared to the untreated wood, but this was not the case for Acacia spp. Generally, the highest improvement in mechanical properties was obtained by modification of Rubber and Acacia woods with butyric anhydride. 1. Introduction Rubber, Acacia, and Oil palm trees are the main supply for plantation wood in Malaysia. The Rubber and Acacia woods have been used for furniture and building materials, while Oil palm wood is used as inner layer of veneer for plywood. However, these wood species are vulnerable to the attack by microorganism such as fungi and termites if the products are used in extreme outdoor condition. In the long term, this will deteriorate its physical and mechanical properties and shorten the service life. Chemical modification has been reported to improve dimensional stability and biological resistance of wood. This treatment is considered as nontoxic to human compared with conventional wood preservative. In chemical modification, the nontoxic compounds get attached into the wood structure and the toxicity problem can be shunned [1, 2]. Wood treated with chemicals such as methyl ether, epoxides, and aldehyde degraded its mechanical properties compared with untreated wood [3]. However, modifying wood with acetic anhydride improves dimensional stability as well as its biological and weathering resistances but gave a little effect on the strength properties of wood [2, 4]. However, there was concern over the influences of acetylation on the strength properties of wood due to its by-product of acetic acid, which resulted either in the reduction of fibre and lignocellulose contents or in a possibility of hydrothermal effect [5, 6]. A comprehensive study on the bending strength of
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