Abstract：In the present research, the urea-formaldehyde prepolymer and multilayer hot-press drying were used to modify poplar plantation. The prepolymer was impregnated into cell lumen space by pulse-dipping machine. Then the timbers were compressed and dried by the multilayer hot-press drying kiln. The results showed that the physical and chemical properties of poplar were changed in this investigation. The basic density of modified wood increased 1.06 times compared with the natural wood, and the bending strength increased 33% for modified wood, compressive strength parallel to grain increased 74%, the water absorption decreased to 97% from 104%. The crystallinity decreased slightly from 39.65 to 36.89 because of the modifier impregnated. TGA analysis showed that the heat resistance of modified wood increased, the three exothermic peaks in DTA curve of modified wood were 280, 360 and 485 ℃ which were higher than natural wood in the corresponding position. FTIR analysis showed that the hydroxyl modified material has a good association phenomenon, and carbonyl content decreased. The SEM spectrum showed the distribution of the prepolymer in the modified timber.
