Iodine‐initiated, solid‐state copolymerization of tetraoxane with 1,3‐dioxolane in the presence of methylal. VII. Treatment of copolymer after polymerization

摘要

AbstractThe various procedures for removing the residual reactants and impurities from the polymer particle obtained by the solid‐state copolymerization of tetraoxane with 1,3‐dioxolane have been examined. The removal of the residual reactants by washing with solvents, such as acetone or water, were very difficult, because the residual reactants are mainly located in the central part of the polymerized particle. By evacuation of the polymeric system just after polymerization, however, the residual reactants were found to be easily eliminated from the polymer particle. It was also found that the polymer degradation caused by the acid impurities formed during polymerization can be prevented satisfactorily by neutralization using gaseous ammonia. On the basis of these findings, the simple process for polyoxymethylene production has been achieved; i.e., it was found that the polymer particle including the residual reactants and impurities can be directly pelletized using a vent‐type extruder, immediately after the copolymerization procedure and the ammonia gas treatment, to obtain the polyoxymethylene pellet with an excellent thermal stability and a well controlled molecular w