41 - POLYMER PREPARATIONS

Abstract

This chapter discusses the polymer preparations of polyesters; polyamides; polyurethanes; acrylic polymers; acrylonitrile, acrylamide, and N -vinylpyrrolidone polymers; and vinyl acetate polymers. The Schotten–Baumann reaction can be applied to the preparation of polyamides using bifunctional reagents. Because the reaction is rapid at room temperature, it can be carried out at low temperatures in solution or by an interfacial polycondensation technique. In the solution polycondensation method, the reaction is carried out in a single inert liquid in the presence of an acid acceptor. The polymer may precipitate out of the solution or it may be soluble. In the interfacial polycondensation method, the reaction is carried out at the interface of two immiscible solvents. The amine is dissolved in water and the acid chloride is dissolved in the hydrocarbon layer. In the casting of polymer sheets, bulk polymerization of initiator-containing monomers may be used, although prepolymers are used commercially to reduce problems arising from shrinkage. Leakage of monomer through the flexible gasketing is also used.