The Polymerization Reaction of Sodium Phosphate

Two kinds of polymerization reactions, the condensation polymerization of sodium dihydrogen orthophosphate anhydrate (NaH2PO4) and the ring-opening polymerization of sodium trimetaphosphate, have been compared by determining the average degree of polymerization of the whole molecule, 0, and of each branch, ∞, and the average number of branches, B, per molecule. As a result, it has been concluded that the remarkable difference between these two reactions can be explained by simultaneous polymerization and depolymerization during the heating. In the case of the condensation polymerization, the polymerization process is more important because the removal of water needs much heating, while, in the case of the ring-opening polymerization, the depolymerization process is more important because the polymerization is completed almost immediately after the material is melted.