Inhibition of leaching of water soluble extractives of Pterocarpus marsupium by heat treatment

Abstract

Pterocarpus marsupium is widely used for constructions, doors, shutters, floorings and furniture. It has good mechanical properties and high natural durability. However, presence of water soluble extractives in P. marsupium restricts its use for certain applications. In this study efficacy of heat treatment of P. marsupium for inhibition of leaching of its water soluble extractives has been investigated. Pterocarpus marsupium specimens were heat-treated under vacuum for different times in the temperature range of 190–220 °C. Effect of the treatment temperature and heating time on color changes and mass loss was studied. Heat-treated wood attained uniformly darker colour. Heat-treated wood specimens were soaked in water and leaching of extractives was quantified by UV–visible absorption spectroscopy. Extractive leaching was significantly reduced in heat-treated wood. Thermal modification of wood was found to be very effective in inhibiting leaching of water soluble extractives of P. marsupium. A moderate mass loss of about 2–4 % occurred for optimum treatment conditions.