The Effect Of Heat Treatment On The Properties Of Poplar

In this paper, the 1-69 poplar is modified by the muffle furnace, vacuum oven, pressure impregnation tank, gamma ray and microwave. Analysis and comparison of changes in the physical properties and corrosion resistance, by analyzing its chemical composition, crystallinity, fiber length, infrared spectroscopy and thermal, we investigated the mechanism of 69-Young modified. The results were as follows:(1) With the increase of treatment temperature and treatment time, the surface color of heat-treated poplar is deepened. And with the extension of the heat treatment temperature and time, the lightness value of L* decreases gradually, the saturation C* and the index of red-green and yellow-blue increases in different degrees, the overall color values △ E* rises with the increase of temperature. From the visual point of view, the color of treated wood becomes deeper and shinier, presents brown or dark brown. And the color of specimen irradiated by gamma-ray changes little, while the color of aspen dried by the microwave is so different in its internal and external because of uneven heating.(2) High-heat treatment is an effective means of improving the dimensional stability of poplar With the rising of the temperature and treatment time, more and more chemical reactions happen inside the wood. The number of hydroxyl groups reduces sharply, and more and more free radicals are produced at the same time. And many new hydrophobic materials created by the chemical reactions make that the shrinkage and bulking of the specimen has a marked impact. And with the increase of treatment temperature and time, the dry shrinkage is smaller and dimensional stability is the better. The 1-69 poplar processed by gamma ray will be improved further because of internal chemical reactions. The aspen dried by the microwave has a large size distortion and it’s easy to have a crack, so the aspen dried by the microwave has poor physical properties.(3)In this study, the physical modification of poplar makes its mechanical properties poor. In the test, the drop of mechanical properties of specimen heat-treated in vacuum reach smallest value, then by carbonization wood, and it modified in steam reach biggest. The poplar processed by y ray can meet the mechanical strength requirement in use. The pressure resistance of the 1-69 poplar modified by the microwave has fallen. And with the rising of treatment time, its pressure resistance decreases distinctly.(4) The modification of poplar makes its anti-corrosion performance improvement. the corrosion resistance of heat-treated wood with the extension of the processing temperature and the rise time. Decay properties of 1-69 poplar modified by gamma-ray with increasing radiation intensity. The microwave sample in the same processing power to handle the longer, the better the corrosion resistance.(5) After those modification, the cellulose and pentosan have decreased. When the carbonization in 200 ℃ and 2hours, the content of cellulose get largest decline, falling from 48.90% to 43.30%. the content of pentosan get decreased up to the heat treatment in steam in 160℃ incubated 2 hours,decreased from 22.80% to 20.37%.