The effect of the composition of the hydrocarbon mixture on the transfer in thermoplastic polyurethanes

The transfer of mixtures of hexane and toluene in thermoplastic polyurethanes used in the production of tanks for temporary storage and transportation of liquid fuels has been investigated. The standard methodology for estimating the diffusion permeability of polymers is not the basis for modeling the natural loss of fuels during storage. A model for estimating natural loss is proposed, the equations of which describe the linear dependences of the decrease in the mass of fuels in tanks in the coordinate of a conditional time equal to the square root of time. The efficiency of the proposed model depends on the composition of the hexane-toluene mixture, since the composition of the mixture affects the limiting stage of the process, which determines the dependence of the natural loss either on the diffusion rate of the fuel in the tank shell, or on the volatilization of the released fuel from the outer surface of the tank.