| Wood is a kind of natural material, which has characters of natural degradation, regeneration and good environmental benignity. With the development of society, the improvement of people's living level and the increasing of the environment consciousness, the wood was focused on again. Though wood is a kinds of excellent building material, it also has its disadvantages, such as flammable and erodible. Every year due to the fire and the intensity decline of wood, many accidents take place, which cause serious hazard to the safety of people's lives and property. With the development of construction and decorating industry and the increasing consuming of wood, the technologies of wood modification are more and more regarded by domestic and foreign researchers.In this paper, the process of wood combustion was introduced. The importance of wood material treated with fire retardant, fire retardants and their categories, the way of wood modification and the mechanism of fire retardant were also reviewed. As the same time, the study and development directions of wood modification were indicated in this paper.By experiment, the modifying agent UDP and DPB composed of dicyandmide, carbamide, phosphate, borate etc. In these modifying agents, there were no As, Cr, halogen and formaldehyde that jeopardize the environment. And the environment contamination was avoided. The impregnation temperature and time, the concentration of modifying agent and the pressure of operation were determined. The fire retardant mechanism of modifying agent to wood was put forward. From the angle of application, the performances of treated white pine and poplar were measured. These performances included fire retardant, decayresistance, dimensional stability, leach resistance, mechanical properties, moisture, metal corrosion and painting property.The optimal technics of wood impregnation was determined. Wood samples was dried at 103 C, and put into an airproof vessel and then the vessel was vacuumize. After 30 min, the modification agent was poured into the vessel, and the vacuum was retained 30 min. Under normal pressure, wood samples were impregnated 24h at 60 C in the solution of UNDP, but in solution of UDP and DPB the temperature was 70 C. After impregnation, wood samples were laid in room temperature 24h, and dried 24h at 50 C, and then were dried at 103C. If wood samples were impregnated under high pressure, the optimal pressure was 0.7MPa, the impregnation time was 8 h.The results showed that by impregnation and polymerization under high temperature, the leach resistance and dimensional stability of UDP and DPB were excellence. Under the normal pressure, the rate of leach resistance of white pine samples was 70.2, while the poplar's was 62.1. Increasing the pressure of impregnation, the leach resistance could be further improved. Under the normal pressure, the oxygen index (OI) of white pine and poplar treated with DPB could reach 74.6 and 67.3 respectively. After 28 weeks of natural soil corrosion, their standards of decay resistance both reached the level of application, the performances of wood treated with UDP were not better than DPB, but they can meet the demands on application. The poplar samples treated with these two kinds modifying agent have similar properties under high pressure. If increasing the pressure of impregnation, the properties of fire retardant and decay resistance can be further improved, but which can make mechanics properties descend.The experiment results also indicated that modifying agent UDP and DPB didn't affect the mechanics properties of the wood basically. Because these two modifying agent has little hygroscopicity, using in high moisture environment,safeguards must be taken. They had nearly no corrosion to metal. The experiment of magnifying sample further proved that modifying agent UDP and DPB had excellence penetration property. Increasing impregnation pressure can promote modifying agent into the inner of the wood and improve the fire retardant property. Compared with wood without modifica...
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