Microwave modification of wood: determination of mechanical properties of softwood

Abstract

Studies of aspen and birch wood interaction with pulsed exposure to microwave energy have been carried out. A method for determining the effect of microwave energy on the temperature inside the test specimen has been developed. It includes experimental setup for studying heat and mass transfer during drying and heat treatment of wood with microwave energy. Moisture content inside wood specimens has been determined by a new method using a laboratory installation for studying the mechanical properties of wood under the influence of microwave energy. This energy influences on the drying speed of the tested wood specimens. The research enables to select the optimal mode of wood heating by pulsed exposure to microwave energy. The results of wood tests for strength and hardness, obtained under the influence of microwave energy, have revealed the effect of wood hardening. The research has shown that microwave treatment of specimens reduces drying time of aspen and birch wood by five times in comparison with convective treatment.

State of the Art of Microwave Treatment of Wood: Literature Review

“…Contrary to previous studies [2,6,[12][13][14]45], the authors reported that the growth in hardness and strength of the surface of birch and aspen wood samples treated with MW represented a scientific innovation. According to these findings and the fact that both species are marginally used due to their low quality, with MW treatment, they could gain in terms of hardening, adding economic value to both species [48].…”

“…This result is in accordance with what Ouertani et al [2] and Oloyede and Groombridge [12] found using different wood species. For instance, compared to Aksenov and Malyukov [48], Oloyede and Groombridge [12] found time reductions even greater for Caribbean pine.…”

“…However, as power was increased, there was a reduction of up to 28% in MOR and 18% in MOE at 1000 W. Considering "MW 300 W" as the MW treatment at 300 W power, "MW 500 W" as the MW treatment at 500 W power, and "MW 1000 W" as the MW treatment at 1000 W power, using the results obtained by Ouertani et al [2], Figure 2 shows the variations in density, MOR, and MOE. Using MW energy, Aksenov and Malyukov [48] investigated the drying duration of both birch and aspen wood and the effect on the strength and hardness of wood samples. To do this, the authors [48] used specimens with MC between 30% and 60% and created an innovative experimental installation with pulsed action.…”

“…It was also observed that the drying rate increases with the values of initial MC; for example, for the reduction in MC from 80% to 60%, the drying rate was 0.12%/s, whereas Using MW energy, Aksenov and Malyukov [48] investigated the drying duration of both birch and aspen wood and the effect on the strength and hardness of wood samples. To do this, the authors [48] used specimens with MC between 30% and 60% and created an innovative experimental installation with pulsed action.…”

“…It was also observed that the drying rate increases with the values of initial MC; for example, for the reduction in MC from 80% to 60%, the drying rate was 0.12%/s, whereas Using MW energy, Aksenov and Malyukov [48] investigated the drying duration of both birch and aspen wood and the effect on the strength and hardness of wood samples. To do this, the authors [48] used specimens with MC between 30% and 60% and created an innovative experimental installation with pulsed action. The results showed that MW drying could diminish the drying time of softwood species fivefold in compar-ison to conventional methods used during their experimental campaign.…”