Microwave drying of Melia dubia and its effect on mechanical properties

This study explores the microwave drying of Melia dubia, with a comprehensive approach that addresses various facets. The primary objectives were to examine drying behaviour and evaluate the drying defects. The drying rates for various treatments were calculated both above and below the fibre saturation point (FSP). The most optimal treatment, characterized by minimal defects, exhibited a drying rate of 0.77g/minute above FSP, 0.39g/minute below FSP, and an overall drying rate of 0.59g/minute. The drying process showed nearly an uniform distribution of moisture, and there were no observable drying-induced defects in the dried wood, suggesting a promising aspect of microwave drying. Static bending and compression tests parallel to the grain were carried out to analyse the impact of microwave drying on mechanical properties. Microwave-dried wood exhibited reductions of 7±3%, 10±2%, and 9±2% in the modulus of elasticity (MOE), the modulus of rupture (MOR), and the maximum compressive strength (MCS), respectively. Examination under light microscopy revealed damage to wood microstructures like ray cells, perforation plates, and vessel walls. The decline in mechanical properties may be attributed to these micro-cracks or damage in its microstructures. These findings emphasize the need for a balanced approach in optimizing microwave drying methods to mitigate the reduction in mechanical properties while capitalizing on the advantages of reduced drying time and uniform drying.