INVESTIGATION OF HYDROTHERMAL PLASTICIZATION PROCESS WITH CONVECTIVE AND DIELECTRIC HEATING

In this paper time needed for convectional and dielectric heating of wood samples to the desired plasticizing temperature was experimentally determined. The temperature was measured using a contactless infrared thermometer on the surface of samples and after their splitting in the spatial center of gravity. The same temperature of the samples was achieved by dielectric heating using microwave radiation six times faster than steaming within convection. Both methods of heating have caused moisture reduction of samples. In the case of microwave heating, the decrease in moisture content was twice as much as steaming. In the second part of this study mechanical properties of samples in a plastic and reference state were measured. The samples were tested in a static three-point bend. The results did not confirm statistically significant effect of heating methods on the degree of wood plasticity. Comparison of the mechanical properties of plastic and reference samples showed the expected large drop due to increased temperature and high moisture content. Test samples were made from beech (Fagus sylvatica L.).