| Polyurethane foam is a kind of useful synthetic materials. Rigid polyurethane foam, with advantages as relative low density, specific strength, thermal conductivity, and easy to combine with other components and simple composite forming, is widely used on structural component area.Previously, chlorofluorocarbons (CFCs) were used as blowing agents in polyurethane foam production. But now people know that CFCs have got destruction of ozone layer. Banning of CFCs as blowing agents resulted in the use of water instead of CFCs, because water is a sort of clean foaming agent to environment.The all-water foaming technique, its advantages and disadvantages, were reviewed. The effect of major technology parameters, including amount of water as well as isocyanate index on the foam properties was discussed.Polyurethane foam possesses fair physical and mechanical properties,acoustical property,the property of electricity and the property of chemical resistance. Especially the temperature conductivity of polyurethane rigid foam is low. Because the polyurethane rigid foam has its own particular point, the material can not be. taken the place of. Meanwhile, the property of polyurethane foam products could be transferred by adjusting the chemical constitution of raw material and the difference of each fractional mixture ratio. So in this way, polyurethane foam will have greatly comprehensive practicability.This article primarily alters the property of polyurethane rigid foam by the filling of nanometer particle and probes even more beneficial foaming process condition,composition for the production of polyurethane rigid foam product. Traditional polyurethane rigid foam prone to be deformation. This kind of foam has low temper and intensity. Filling nanometer sio2 could enhance its mechanical property and increase its intensity. In this way, polyurethane rigid foam can more even comprehensive applies to all walks of life .In our study , we synthesized nano-silica in W/O microemulsion with polyether polyol as the oil phase .The polyether polyol then react with TDI to prepare rigid polyurethane foams (PUFs) via a new process ,using the water in the microemulsion as blowing agent.It is found that this new method can solve the problems of scorch , subside and shrink which appear during the process of preparation of rigid polyurethane foams . We studied the affect of the processing conditions such as the stirring time , pH and the amount of TEOS on the preparation of W/O microemulsion and the synthesis of nano-silica , and the processing conditions such as the using amount of TDI , the content of water in the microemulsion ,the stirring time and the amount of catalyzer on the preparation of rigid polyurethane foams .The properties of the synthesized PUF samples were investigated with a FTIR Spectroscopy , a DSC instrument and a universal testing machine . From the FTIR spectrum ,we found that there exist a lot of polyurea and amine besides polyurethane in the PUF samples . The results of the investigation of the mechanical properties of the PUF samples showed that the mechanical strength of the PUF samples was increased with the addition and increasing amount of silica in the rang of 0～2%, which is larger than that of PUF samples prepared via blending method . From the results of the thermal analysis of the PUF samples , it was found that the glass-transition temperatures of the PUF samples containing 2% of nano-silica is 360℃, which .is 60℃higher than that of PUF samples (300℃) without nano-silica.
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