The Properties And Classification Of Heat-treated Wood

The Pinus sylvestris var.mongolica,Pinus contorta,Larix gmelini and Pinus massoniana were heat treated at temperatures from 180℃to 230℃for times from 1h to 4h in airtight equipment with an atmosphere within comprising less than 2 per cent of oxygen content. Aims of this Research is to know about the physical changes of dynamics and laboratory performance of heat-treatment and middle-style treatment of the wood and performance gap between the different positions wood treatment of middle-style performance relationship based on the outcome of the treatment of wood. classification. Saturated steam was used as a heating medium and a shielding gas.Steam heat treatment has been known the treatment leads to a darkening of the wood color which can also be a beneficial aspect of the treatment. Unfortunately, undesired side effects, in particular the loss of strength and increased brittleness of the heat-treated wood, have prevented the commercial utilization of thermal modification. Mathematical regression models relating to the treatment temperature, treatment time and the properties of the heat-treated wood were established, along with mathematical regression models comparing loss ratio of bending strength and other properties of the heat-treated wood. through main ingredient analytical methods to analyse the statistics on heat-treated of wood,and explored the method of classification of soft-wood.The main research results are summarized as follows:1). In the condition of test , the maximum increase rate of dimensional stability by Pinus sylvestris var. mongolica,Larix gmelini, Pinus contorta and Pinus massoniana are 41.43%,48.88%, 44.42% and 48.01% after high temperature heat treatment .With the heat treatment temperature increased and the holding time extensed, the dimensional stability of wood gradually increasing .Temperature and time factor analysis of variance results shows that temperature and time are significant on the shrinkage and swelling mean , temperature and time effects significantly on improving the dimensional stability of wood .2). High temperature heat treatment can significantly reduce the equilibrium moisture content of wood .In the condition of test , the equilibrium moisture content of dimensional stability by Pinus sylvestris var. mongolica,Larix gmelini, Pinus contorta and Pinus massoniana are reduced 45% , 50% , 52% after high temperature heat treatment .With the heat treatment temperature increased and the holding time extensed , wood equilibrium moisture content showed a decline by the law .3). High temperature heat treatment can change bending strength and the modulus of elasticity of wood. The highest improving ratios of the bending strength are 15.31% of the Pinus sylvestris var. mongolica with treatment under low temperature. The loss ratios of the bending strength of Pinus sylvestris var. mongolica,Larix gmelini, Pinus contorta and Pinus massoniana respectively are 22.29%,39.62%,25.63% and 31.33%.4). High temperature heat treatment can significantly make the color of wood become darker. In the condition of test, with the increase of temperature and time, the treatment making the wood color become darker and darker. The color of heat-treated wood becomes brown and puce with the increasing of temperature and time during the heating process. In this study, the range of variance value of△L*,△E*,△C* in Pinus sylvestris var. mongolica,Larix gmelini, Pinus contorta and Pinus massoniana .There is a significant difference at the 0.01 level between the color of the wood and the temperature. This data indicates that the heat treatment changes the color of wood significantly.5). High temperature heat treatment can significantly enhance the natural durability of wood. In the condition of test, with the increase of temperature and time, the natural durability of Pinus sylvestris var. mongolica,Larix gmelini, Pinus contorta and Pinus massoniana wood can significantly enhance. High temperature heat treatment can make the natural durability grade toⅠgrade. The wood could arrive natural durability grade ofⅠat treatment temperature of 230.6). The paper compares the mechanical-physical properties of Pinus massoniana under laboratory treatment with that of pilot-scale treatment in 200℃。The results show that the differences of all mechanical-physical properties between the two treatments were not significant,the differences of all mechanical-physical properties in different position of same kiln with high temperature pilot-scale treatment were not significant。 7). In this paper, with spss16.0 software for data clustering, through main ingredient analytical methods to analyse the statistics on heat-treated of Pinus sylvestris var. mongolica and Pinus contorta wood. Pinus sylvestris var. mongolica and Pinus contorta wood are gathered into four clusters.The properties of control group of Pinus sylvestris var. mongolica have small dierence with the heat-treated wood under 200℃, so they are cluster to one class. There is a highly significant difference at the 0.01 level between the properties of Pinus sylvestris var. mongolica wood. The properties of control group of Pinus contorta have significantly dierence with the heat-treated wood, so the control group cluster to one lonely class. There is a highly significant difference at the 0.01 level between the properties of Pinus contorta wood.