## 3 Results and Discussion  
Mechanical properties of the samples including MOE, MOR and hardness values of four different of temperature levels are listed in Table 1. MOE and MOR values of control samples were 6280 N/mm\({}^{2}\) and 107.11 N/mm\({}^{2}\), respectively being the highest among the other specimens. Both properties of the samples decreased 1.05, 1.17, 1.64, 1.44, 2.37, and 3.70 times than those of control samples as a result of heat treatment at temperatures of 150, 180 and 220 \({}^{\circ}\)C. Previous studies also showed that negative effect of heat treatment on mechanical properties of wood [4; 10; 16]. In a past work bending properties of heat treated North American Jack pine also showed reduced values similar to those determined in this work [21]. Figure 1: Microwave heat treatment set-up. Overall hardness of the samples also followed the similar trend as a result of heat treatment. It was found that heat treated eastern redcedar samples exposed to a temperature of 190 \({}^{\circ}\)C for 6-h had 50% reduction in their Janka hardness values and had a certain amount of brittles and crushed during the hardness test [17]. Although the samples also had reduced hardness values as function of heat treatment but no crushing or any other deformation on them was observed. This could be related to only twenty minutes heat exposure time used in this work which could be considered as main advantage of microwave heat treatment approach. Table 2 displays swelling values of the samples soaked in distilled water for 2-h and 24-h. Control specimens had swelling values of 1.60%, 1.86%, and 0.24% for 2-h and 2.67%, 2.96%, and 0.44% for 24-h for radial, tangential, and longitudinal grain orientation, respectively. Heat treated specimens at a temperature of 150 \({}^{\circ}\)C had reduced corresponding values of 64.90%, 46.97%, and 4.90% of 2-h and 15.64%, 11.10%, and 2.01% of 24-h compared to those of control specimens. As temperature level was increased to degrees of 180 and 220 higher positive influence of heat treatment on dimensional stability of the samples can clearly be seen from Table 2.  
The values of oven dry density, weight loss of treated samples gradually decreased as presented in Table 3. The density of heated specimens had values of 648 kg/m\({}^{3}\), 613 kg/m\({}^{3}\), 611 kg/m\({}^{3}\), and 556 kg/m\({}^{3}\) for control samples and those exposed to temperatures of 150 \({}^{\circ}\)C, 180 \({}^{\circ}\)C and 220 \({}^{\circ}\)C, respectively. Wood being a hygroscopic material absorbs moisture from the surrounding environment resulting in dimensional changes [29,30]. Therefore how much moisture is absorbed plays a significant role on the member during its service life [31,32]. Samples treated at a temperature of 220 \({}^{\circ}\)C and soaked in the water for 24-h had 19.39% water absorption which was 1.38 times lower than that of the control sample. It is clear that water absorption values of the samples were improved as a result of heat treatment as can be seen in Table 3[26, 27, \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Temperature**} & \multicolumn{6}{c}{**Swelling in Water Soaking (\%)**} \\ \cline{2-7}  & \multicolumn{3}{c}{**2-h**} & \multicolumn{3}{c}{**24-h**} \\ \cline{2-7}  & **Radial** & **Tangential** & **Longitudinal** & **Radial** & **Tangential** & **Longitudinal** \\ \hline
0 & 1.60 (0.38) & 1.86 (0.47) & 0.24 (0.07) & 2.67 (0.49) & 2.96 (0.56) & 0.44 (0.05) \\
150 & 0.562 (0.23) & 0.988 (0.17) & 0.23 (0.05) & 2.25 (0.47) & 2.63 (0.48) & 0.43 (0.14) \\
180 & 0.474 (0.16) & 0.878 (0.10) & 0.21 (0.02) & 1.62 (0.43) & 2.56 (0.32) & 0.43 (0.06) \\
220 & 0.243 (0.21) & 0.472 (0.37) & 0.20 (0.03) & 1.49 (0.22) & 2.34 (0.60) & 0.42 (0.09) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Mechanical properties of the samples. (The numbers in parentheses are the standard deviation values).