Drying of Rubbers Containing a Liquid

As shown in Reference [6], a book devoted to the subject of drying polymers and rubbers the process is rather complex. In fact, the process of drying a rnbber is controlled either by diffusion of the liquid through the solid or by evaporation of the liquid in the vapor state at the surface. The diffusivity can be concentration-dependent when the liquid concentration in the rubber is large or constant when this concentration is small. The rate of vaporization appears in the coefficient of surface convection in Equation 7.8. 

the process is defined for a sheet by the following two equations  

In fact, in order to get the snrrounding atmosphere free from vapor, it is necessary to stir the solid surface so as to eliminate the vapor from the rubber surface. 

As the evaporation is endothermic, the surface of the rubber is cooled differently during the stage of drying, depending on the rate of evaporation. 

The problem cannot be resolved mathematically, and a numerical model taking into account the following stages the diffusion through the thickness of the rubber, evaporation at the surface, and change in dimension of the rubber sheet, should be built and tested. 

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