Effect of microwave pre-treatment on preservative retention and treatability of Melia composita wood

Abstract

The species Melia composita has come to prominence only during the last decade and has been found suitable for several applications and end uses. However, being non-durable and difficult to treat some pre-treatment is required to improve preservative uptake. Hence the effect of microwave (MW) pre-treatment was studied on the samples of Melia composita wood in order to ameliorate its retention, depth of penetration and treatability class to ensure its sustainable use for a longer duration. The samples were exposed to MW radiation of different intensities and treated with 6% solutions of CCA, ZiBOC, CCB and Borax boric acid (BBA) preservatives by a dip diffusion method for 24 hours. Results showed a significant improvement in preservative uptake after dipping for 24 hours, in comparison with the controls. The highest retention was found in the samples treated with ZiBOC preservative after their MW exposure to 840 MJ.m-3. Wood anatomical analysis after MW modification was also performed in order to assess the changes taking place within the wood microstructure. The cross-sectional analyses of the controls and the treated specimens were briefed accordingly. Results of the anatomical study exhibited a significant improvement in the effective vessel diameters of the microwave irradiated specimens due to the clearance of the occlusions blocking the vessels with respect to the control samples, which aids in increasing wood permeability and results in higher retention and penetration.

Keywords

• microwave modification
• permeability
• melia composita