Rheological molecular weight distribution determination of ethylene/ tetrafluoroethylene copolymers: Implications for long-chain branching

The molecular weight distributions of ethylene/tetrafluoroethylene copolymers (PETFE) were estimated by dynamic mechanical analysis of their melts. The validity of the method had been established on model polystyrenes. The high temperatures required for solubility prevented analysis by classical techniques. Our results indicated much broader distributions on dilute PETFE solutions using a unique high-temperature laser light scattering procedure. Dynamic mechanical analysis was performed on one of the samples after dissolution, filtering and drying to reveal no significant change versus the originally analyzed melt. This indicated that the conditions required to treat the solutions during the light scattering tests were not appreciably altering the polymer nor filtering out an insoluble portion.