Study On Solution-diffusion Behavior And Elution Technology Of Pore-forming Agent From Silicone Rubber Foam

Silicone rubber foam have been widely used in modern society as a porousmaterial. Recently, however, more attentions have been paid to the practicability ofsilicone rubber foam. The study on basic theories was few. This paper studied thesolution-diffusion process of pore-forming agent, urea, in aqueous solution fromsilicone rubber foam and improved its elution technology.A solution-diffusion mathematical model was proposed to describe thedissolution process of urea from silicone rubber foam. The model was simulated andanalyzed. The difference method was used to solve the mathematical model to gainthe numerical solution. The experimental results were compared with the calculatedresults. It was found that the mathematical model had a good simulation result. Theconcentration distribution at different time and the change of concentration with timeof urea in silicone rubber foam were simulated by the model.It was showed that the effective diffusion coefficient and water consumptionwere the main factors affecting the dissolution of urea. The influences of effectivediffusion coefficient, water consumption, temperature, viscosity of aqueous phase andwater renewing were simulated. The results of simulation showed that the dissolutionrate of urea was increased when the effective diffusion coefficient was increased, thewater consumption was reduced, the temperature was raised or the viscosity ofaqueous phase was reduced. Introducing assistant or renewing water could alsoincrease the dissolution rate of urea.The non-ionic surfactants, AEO-5, OP-10and AEO-9, were used in the elutiontechnology of pore-forming agent, urea, from silicone rubber foam. The effects ofdifferent non-ionic surfactant, elution temperature, surfactant contents, the mass ratioof sample of silicone rubber foam to surfactant aqueous solution and the frequency ofrenewing water on elution were studied.The study indicated that non-ionic surfactant could increase the elution rate ofurea efficiently and the result of AEO-5was better than that of AEO-9and OP-10. The better elution technology (1) obtained by orthogonal experiments was1:10,0.3%,1/3h-1and60℃for the mass ratio of sample of silicone rubber foam to AEO-5aqueous solution, AEO-5contents, frequency of renewing water and elutiontemperature, respectively. Based on the consideration of saving resource and reducingenergy consumption and ensuring a good elution result, the technology (2) wasproposed as1:10,0.1%,1/4h-1and60℃for the mass ratio of sample of siliconerubber foam to AEO-5aqueous solution, AEO-5contents, frequency of renewingwater and elution temperature, respectively. The two kinds of better technology werecompared and technology (2) was selected as the final elution technology. Under theconditions of technology (2), urea was eluted completely after48h.