1. A PROCESS FOR COPOLYMERIZING AN OXYMETHYLENE PRODUCING MONOMER AND ANOTHER VAPORIZABLE MONOMER HAVING A BOILING POINT OF LESS THAN 300*C. WHICH IS CHEMICALLY DIFFERENT FROM SAID OXYMETHYLENE PRODUCING MONOMER, WHICH PROCESS COMPRISES VAPORIZING EACH OF SAID MONOMERS, MIXING THE VAPORS THUS OBTAINED WHILE MAINTAINING THE VAPORS ABOVE ABOUT 125*C., THE MAXIMUM TEMPERATURE AT WHICH SAID VAPORS WILL COPOLYMERIZE, CONTACTING SAID VAPORS WITH A COPOLYMERIZATION CATALYST, AND THEREAFTER COPOLYMERIZING THE MIXED MONOMERS AT A REDUCED TEMPERATURE.