Application Characteristics Of Heat-treated Wood In Energy Saving Windows And Doors

Heat treatment was applied to the wood of P. tomentosa by superheated steam at the temperature of 160, 180, 200 and 220? for 3h. The effects of heat treatment on wood thermal conductivity, heat transfer characteristic, physical and mechanical properties were studied. Finally, composite structure was researched on treated and meterals wood in order to optimize the mechanical properties and thermal properties. The result showed:1, Heat treatment reduces the thermal conductivity of Populus, and the higher heat treatment temperature the smaller thermal conductivity.Unsteady heat conduction results showded that heat treatmentreduces the heat transfer rate of wood.2, Wood EMC, oven dry density, ?-cellulose, hemicellulose and porosity all affect the heat transfer characteristics of Populuswood.There is a positive relationship between thermal conductivity andwood EMC, oven dry density, ?- cellulose, hemicellulose, There ia a negative relationship between thermal conductivity and porosity.3, Wood EMC, oven dry density with thermal conductivity of wood is established the regression model:? = 0.428- 7.378 × 10 ? + 0.111;Wood EMC, ?- cellulose, hemicellulose, porosity with thermal conductivity of wood is established regression model:? = 0.087 + 0.281 + 0.079 + 0.089?- 0.072; Two regression models provided above can be used to predict or assess treated wood thermal conductivity.4, Heat treatment made the porosity volume of wood increase, especially the number of less than 70 nm mesoporous, which made thermal conductivityreduce.5, Heat treatment does not change the position of crystalline regions, but affect the crystallinity obviously, at the temperature of 160?, 180?, 200? and 220?, the crystallinity increase 5.5%, 11.29%, 5.57% and 7.19%. Mass loss rate mainly affect the MOR and nail holding power during the heat treatment, crystallinity mainly influenced the MOE, both Mass loss rate and crystallinity affect the impact toughness and surface hardness.6, Parallel Composite of C-T180 and C-T220 improve the MOR and impact toughness of the material effectively. However, Cross composite, due to natural layer(heat treated material) has a smaller stripes MOR and impact toughness, has a weak mechanical strength. Therefore, Cross composite should not be considered in the actual production.7, MOR and impact toughness of parallel C-T180 have reached the maximum when the thickness proportionis 3/14/3;MOR and impact toughness of parallel C-T220 have reached the maximum when the thickness proportionis6/8/6. This way can get good insulation properties when the mechanical propertiesreachmaximum.Thermal conductivityof parallel C-T180 is 0.1357 W/(m·K)when the thickness proportionis 3/14/3,which reduce 11.07% compared with untreated wood; Thermal conductivityof parallel C-T220 is 0.1398 W/(m·K)when the thickness proportionis6/8/6, which reduce 8.38% compared with untreated wood;8, Materials thickness proportion of 4/12/4 and 3/14/3 of C-T180 and 6/8/6 of C-T220 can both meet the energy-saving windows and doors material requirements on mechanical and thermal conductivity properties.