Chain transfer polymerization agents Tetrafluoroethylene

In solution polymerization, monomers mix and react while dissolved in a suitable solvent or a liquid monomer under high pressure (as in the case of the manufacture of polypropylene). The solvent dilutes the monomers which helps control the polymerization rate through concentration effects. The solvent also acts as a heat sink and heat transfer agent which helps cool the locale in which polymerization occurs. A drawback to solution processes is that the solvent can sometimes be incorporated into the growing chain if it participates in a chain transfer reaction. Polymer engineers optimize the solvent to avoid this effect. An example of a polymer made via solution polymerization is poly(tetrafluoroethylene), which is better knoivn by its trade name Teflon . This commonly used commercial polymer utilizes water as the solvent during the polymerization process,... 

A terpolymer of tetrafluoroethylene, hexafluoro-propylene, and perfluoropropylvinyl ether was re-ported " ] to have superior stress crack resistance than TFE/HFP copolymer. The terpolymer in this development was prepared by the nonaqueous polymerization process described in US Patent numbers 3,528,954 and 4,029,868.In this procedure a halogenated solvent, in which perfluoropropylvinyl ether and a chain transfer agent had been dissolved, acted as the polymerization medium. Methanol was a common example of an effective chain transfer agent. Polymerization was carried out in a stainless steel pressure vessel. The polymer contained 0.2-2% perfluoropropylvinyl ether and 9-17% hexafluoropropylene. 

Tetrafluoroethylene, g TFErCOj = 1 1 Initiator Type Chain Transfer Agent/Amount, mi Initiator Amount, mg Polymerization Polymerization Yield, wt% First Melting Point, °C Second Heat of Fusion, J/g ... 

---