Ontwikkeling van een 'silica menger': aanpassing van bestaande mengapparatuur
dipl. chem. W.K. Dierkes, Universiteit Twente
Development of a new mixer design for silica compounds W.K. Dierkes and J.W.M. Noordermeer Twente University, Faculty of Chemical Technology P.O. Box 217, 7500 AE Enschede, The Netherlands Silica as a filler has a low compatibility with the rubber matrix due to its hydrophilic surface. A good dispersion of the filler can only be achieved by using a coupling agent, which reacts with the filler surface under the formation of a hydrophobic shell around the filler particle. During this chemical equilibrium reaction ethanol is generated and therefore the reaction rate is reduced by high concentrations of alcohol in the compound. The equilibrium can be shifted towards the silanisation products by removal of ethanol. Different mixing conditions for optimal ethanol evaporation were tested in laboratory mixers and scaled up to production size. Influencing factors such as rotor geometry, fill factor, air injection, temperature settings and mixer opening when working in an open mixer were investigated. An increase of the efficiency of alcohol removal by various measures indeed results in a higher efficiency of the silanisation reaction. The degree of silanisation when working in an open mixer was measured for different time-temperature profiles. The kinetics of the silanisation reaction has been investigated and the processing window for the reaction has been determined.