REDUCED COMBUSTIBILITY PHENOLIC BINDER

Phenolic resins are widely used for preparing fireproof materials due to the coke formation ability on combustion and comparatively low cost. To reduce flammability oxyalkylphosphonates of different polyols are often introduced into phenolic composition. Meanwhile the synthesis of organophosphorous compounds uses ecologically hazardous substances which production has been discontinued. This paper studies the possibility to achieve high fire safety characteristics for phenolic binders without organophosphorous compounds. The correlation between phenolic binder composition, thermooxidative stability of cured polymer and heat release upon burning of composite based on the binder was studied. It was found that the binder containing resol and novolak oligomers could be used for the production of glass laminate that meets the Airworthiness Standards: it is hardly flammable, has low smoke emissions and have the peak heat release rate of 45 kW
m2 and the average total heat release during the first 2 minutes of 19 kW·min
m2 . Even better performance could be achieved by modification of the binder with extremely small amounts (0.03–0.07 %) of chloroplatinic acid. The study of thermooxidative destruction by thermogravimetric analysis (TGA) has shown that addition of chloroplatinic acid leads to increase of temperatures of 5 and 10 % loss of weight of the cured polymer to 50 and 90 °Ñ, respectively, and the coke yield raises from 56 to 65 %. Glass laminate based on the binder modified by chlorîplatinum acid has the peak heat release rate of 28 kW
m2 and the average total heat release during the first 2 minutes of 11 kW·min
m2 . Thus, the study has shown that the application of platinum compounds, in this case chloroplatinic acid, can efficiently decrease heat release on burning of phenolic composite materials, allowing to avoid the use of organophosphorous retardants. The presence of hundredths of a percent of platinum in polymeric matrix provides two times decrease in heat release of the material.