Thermal Modification of Bamboo : A Chemical-Free Processing Technique for Improving the Properties and Performance of Products

Abstract

Thermal modification is one of the ecofriendly alternative processing techniques for improving various properties of bamboo including dimensional stability and decay resistance. The heat treatment protocols for producing thermally modified (TM) bamboo have been worked out in the laboratory for different species. The TM bamboo exhibited improved properties particularly lower shrinkage and swelling, higher water resistance, darker brownish colour and enhanced decay resistance against fungi and borers. When bamboo is subjected to heat treatment temperatures above 200°C for longer durations (>8 hours), the flexural strength is found to be adversely affected. By thermal processing, not only decay factors of bamboo are eliminated but dimensional stability and resistance to moisture related problems are also improved. TM bamboo with improved aesthetic and quality parameters may be used for production of certain value-added “green productsâ€. A few composite boards were produced successfully in the laboratory using TM bamboo. The bamboo culms of required dimensions were thermally modified and converted into thin strips or crushed bamboo, which can be processed further into sturdy composite panel products such as laminated bamboo lumber (LBL) or bamboo strand lumber (BSL) or so called “bamboo timberâ€. Thus, thermal modification of bamboo may be considered as an ecological alternative to preservative chemical treatments. The thermally modified bamboos may be used for different valued-added products such as furniture, flooring tiles, bamboo boards and strip-based panel products in structural and non-structural industry sectors. Through successful implementation of up-scaled processing, this technique may lead to prospective business opportunities and bamboo-based industry of the country may utilize TM bamboos for production of various life-style products.