The Studies Of Synthesis And Modification Of Phenolic Resol Resin And Its Foam

Phenolic resol foam is synthesized by foamable phenolic resol rein. It has lots of excellent properties, including heat preservation, low coefficient of transmit heat, corrosion resistant, aging resistant, sound absorption and so on. People have recognized the practicality of plenolic foam as a heat preservation material in building and the vent of central air-conditioning because of the low flammability, low smoke density and toxicity of it. However, phenolic resin contains high contents of free phenol and free formaldehyde that cannot be removed substantially. Phenol and formaldehyde are toxic for human beings and they can also cause environmental problems. In addition, structural applications of phenolic foam have been severely limited because of the extreme brittleness and friability. Traditional phenolic foam cannot meet its need today. Reducing the contents of the free phenol and free formaldehyde, enhancing the toughness of the phenolic resin by modification are the developing trend of it.In this paper, the influence of different formaldehyde/phenol molar ratios, catalysts, reaction temperature and time on the contents of remnant monomers free formaldehyde and free phenol in foamable phenolic resol resin were studied. A better method of decreasing free formaldehyde and free phenol during the synthesis of phenolic resol resin was investigated. With this method, the phenolic resol resins were modified by flexibility agents, such as acrylic acid, polyvinyl alcohol, polyvinyl butyral and polybutylece terephthalate in detail. The results showed that the contents of free formaldehyde and free phenol in modified resins are much less than that of the pure one.Then the mechanical properties and thermodynamic stability of pure phenolic resin and modified resins were well compared. The analytical results indicated that the mechanical properties, such as tensile strength, flexibility and impact strength of modified phenolic resol resins are increased respectively, and the thermodynamic stability of resins is not influenced. And the phenolic resin modified by polybutylece terephthalate is the best of all. At the same time, the relation between structure and property is analysised by FT-IR. The possible reaction scheme and toughing principle were deduced on the basis of these...