THE METHODS OF IMPREGNATION AND THERMAL MODIFICATION OF WOOD

Abstract

Solid materials are classified into a few main groups, such as, metals, ceramics, polymers, and composites. Naturally-occurring wood is classified into the composite group, and it is one the oldest materials utilized by human beings. Today, several different materials are available to meet the needs of the modern society, and selecting the right material may be a problem in many places. However, the economic point of view can be the deciding factor in the material selection. A material may contain an ideal set of properties but be prohibitively expensive (1).

In addition to the positive environmental impact, wood has a large number of favorable properties which contribute to its use in many applications. Favorable properties are, inter alia, easy workability, good insulation, and high strength compared to weight. However, some of the inherent properties of wood impair its competitiveness, such as vulnerability to moisture, biological organisms, and weathering. Due to its hygroscopic nature, several physical properties of wood become undesired with the moisture change. Wood starts to shrink when moisture is removed below the fibre saturation point (FSP), and contrarily, dry wood starts to swell with water contact. The shrinkage and swelling of wood varies between the growing directions due to its anisotropic nature (4). Depending on the temperature and moisture conditions, biological organisms may attack wood and degrade its quality (2). Environmental factors, such as solar radiation, can destroy the texture of the wood surface, which is reflected as a grey, cracked, or rough surface (3).These susceptibilities have led to the development of wood protection to enhance the qualities of wood. Several countries have made significant investments in the research of wood preservation (5).

The development towards urbanization and demographic evolution will affect the requirements of building products (1). The competing products can reduce the use of wood. The construction industry is a big user of wood products, and wood-frame buildings have become common in several European countries. Wood is a safe material under high stress conditions, but the challenge for wider utilization is national fire regulations, which restrict the use of wood in many countries. However, it should be remembered that a layer of char is created when wood burns, and this char layer ensures the structural integrity of wood, reducing the risk of collapsing concurrently. The opportunities relating to the use of wood in construction are not fully exploited. at the moment A positive building policy toward wooden multi-storey construction can lead to a larger use of wood, and using more wood in construction could save global carbon dioxide (CO2) emissions and fossil fuel consumption substantially (3).