No abstract

The Gibbs elasticity modulus represents an important tool to predict the foamability for transient and permanent foams like polyurethane flexible systems. Elasticity is related to foamability and so is used as a synonymous for the purpose of this paper. In this article we propose a method and a thermodynamic model to analyze the espumability of silicone surfactants in polyol binary mixtures using surface tension data. The present work describes foamability through the Gibbs elasticity modulus expressed in terms of first and second derivatives of surface pressure vs bulk composition. Furthermore, the Gibbs adsorption equation and the corresponding novel surface equation of state based on a modification of the Langmuir isotherm resulted in an elasticity equation with analytical solution. It is shown that according to foam model systems of surfactant solution in polyol used at commercial processes, optimum concentration level of surfactant obtained at this article by Gibbs adsorption equation and maximus on elasticity modulus finally match.

In the present work, the height of foam column has been used to monitor the reaction of the isocyanate group. Kinetic modeling describes the conversion versus time curves. The global reaction can be divided into two different paths: the blowing reaction and the polymerization. The kinetics of the reaction of toluene diisocyanate with a polypropylene glycol has been studied with auxiliary blowing agents; the concentration of NCO and OH groups could be considered equivalent during all the experiments as a model for similar polyurethane systems. Despite the complexity of the system in which different kinetic orders are possible, as well a physically controlled diffusion process, data were fitted to a simple kinetic model of an apparent order. The results obtained have enabled us to propose a reaction path and catalyzed second‐order kinetic model.