The Research On Properties And Structure Of Silica Nanoparticles/RPU Composite Foam

The polyurethane is applied in many filed for it's excellent properties such as structure-designable,. In order to improve the properties of mechanical property, heat insulation and flame retardance properties, the polyurethane were often combined with various inorganic fillers to produce polyurethane composite foam. Silica is typical zero dimension materials which could be produced by sol-gel method and Vapor phase method, and its size could tuned in the range of 10 nm to 900 nm. In light the hydrogen bond on its surface, surface modification could improve the properties and disperation in matrix.so the silica nanoparticles are occupied an important place in matrix industry. With the development of technology, the new synthesis methods of silica nanoparticles and hollow mesoporous silica have been discovered and developed, and the silica nanoparticles provided some new challenges and chances for composite materials.The research on silica/polyurethane composite foam were mainly focus on silica nanoparticles with its size less than 100 nm recently, and its poor desperation in matrix is leading to surface modification. Certainly the modification is obviously increase the viscosity in one hand and decrease the process performance in the other hand. The new type hollow mesoporous silica has great potential of improvement of polyurethane composite foam. The influence on foam structure, mechanical properties and nucleation are worthy to research. In light the discussion above, our study are focus on the following aspects.[1] Ordinary solid silica with different size (460 nm and 718 nm) were synthesis by sol-gel methods while hollow mesoporous silica was also synthesis by modified Stober method(685 nm).the influence of the concentration of precursor, the ratio of water/ethanol on silica size and morphology and properties were investigated. The result have indicated that the size of silica nanoparticles were strongly influenced by the amount of TEOS and ammonia and the ratio of water/ethanol. The size of silica nanoparticles could controlled by tuning the addition of the amount of TEOS? ammonia and the ratio of water/ethanol. The results of TEM and SEM show that the solid silica have spherical solid structures and the hollow spherical mesoporous structures. And the Nitrogen sorption results indicating the mesoporous structures.[2] The RPU with the addition of different size solid silica (460 nm and 718 nm) were synthesized, the structure of foam, mechanical property, dimensional stability and thermal conductivity, the result showed that compared the pure PU foam, the T-720 silica nanoparticles/PU composite foam have expressed better properties in light of the dispersion in resin when the addition was 1%, the comprehensive strength was increased 10% while the T-400 silica nanoparticles/PU composite foam was increased 5%.[3] Using the new type hollow mesoporous silica as a filler, the silica/polyurethane composite foam is fabricated. The solid silica/polyurethane foam was also fabricated for comparison. The nucleation of different types nanoparticles and the influence on pore structure (cell size, percentage of open area), mechanical property and heat insulation were investigated. The differences and similarities between them were also investigated. The result showed that compared the pure PU foam, the HMS silica nanoparticles/PU composite foam have expressed much better properties in light of the mesoporous structure which leading lower nucleation energy barriers, when the addition was 1%, the comprehensive strength was increased 20% while the SS silica nanoparticles/PU composite foam was increased 10%.