A STUDY OF RAPID SOLIDIFICATION OF HYDROCARBON FUELS

Progress is reported on rapid methods for gelling aircraft fuels. One of the more promising systems developed is the use of fatty amines and tolylene diisocyanates. Systems were developed that will gel fuel with as low as 1.0 weight percent additives. The rate of gelation and the properties of the gel are influenced by the structure of the amine and the diisocyanate. Pure 2, 4-tolylene diisocyanate and lauryl amine yield a soluble product. With mixture of the 2,4-isomer and 2,6-isomer, the rate of gel formation and rigidity of the gel increases as the concentration of the 2,6-isomer increases. With pure 2,6- tolylene diisocyanate and lauryl amine, the rate is so fast that adequate mixing cannot be obtained using normal laboratory techniques. This gelation process significantly decreases the vapor pressure of the fuel and thus greatly reduces the fire hazard caused by fuel misting. Other fuel gelling systems have been developed. At a 4 percent concentration, the reaction product of an acrylic acid copolymer and ntetrabutyl titanate in JP-4 produces an elastic gel having excellent strength.