Gelation

Gelation is a process associated with polymers. To explain more, we have to define a constant, branching coefficient a which is actually the probability that a given functional group on a branch unit is connected to another branch unit. Branch unit is a unit of functionality greater than 2. To identify the gel point precisely, we have to note the time when the polymerizing mixture suddenly loses fluidity. One indication for losing fluidity is stopping of emergence of bubbles. When we are treating reaction process as a function of time, by a tool where aliquots are removed from the solution and subsequent titration for the present functional groups, precise evaluation of gel point is possible. It is a common fact that the experimentally observed branching coefficient differs with the theoretically predicted value. This disagreement is due to the reaction of some functional groups to form intramolecular links, which do not contribute to network structures.